Chapter 1: The Human Organism
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1.1 Anatomy
study of the structure and shape of the
body and body parts & their relationships
to one another.
comes from the Greek words meaning
to cut (tomy) apart (ana).
the art of separating the parts of an
organism in order to ascertain their
position, relations, & structure
Anatomy means to dissect, or cut apart
and separate, the parts of the body for
study.
Importance: helps in understanding the
functions of the body.
Subdivision of Anatomy
1. Gross or Macroscopic
● Regional Anatomy
● Systemic Anatomy
● Surface Anatomy
2. Microscopic Anatomy
● Cytology
● Histology
3. Developmental Anatomy
4. Pathological Anatomy
5. Imaging Anatomy
1. Gross Anatomy
➔ The study of structures that can be
examined without the aid of a microscope
(seen by the naked eye)
➔ Considers large structures such as the
brain, muscles, bones, various organs
◆ Regional Anatomy (Specific Area)
● Studied area by area (head,
abdomen, or arm)
● Studying regional anatomy helps
appreciate the interrelationships
of body structures, such as how
muscles, nerves, blood vessels,
and other structures work
together to serve a particular
body region.
● Mostly
used
in
graduate
programs at medical and dental
schools.
◆ Systemic Anatomy (Organ System)
● study of the structures that make
up a discrete body system—that
is, a group of structures that
work together to perform a
unique body function.
● Studies system by system
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Study of specific system:
Integumentary
Nervous
Respiratory
Endocrine
Skeletal
Digestive
Cardiovascular
Muscular
Urinary
Reproductive
Immune
Lymphatic
➔ Surface Anatomy (External)
◆ anatomy that we can see at the
surface of the body; superficial
structures
to
locate
deeper
structures
◆ study external features (ex. skin),
such as bony projections, which
serves as landmarks for locating
deeper structures.
For example, the sternum
◆
(breastbone) and parts of the ribs
can be seen and palpated (felt) on
the front of the chest. Health
professionals use these structures
as anatomical landmarks to identify
regions of the heart and points on
the chest where certain heart
sounds can best be heard.
2. Microscopic Anatomy
➔ study of body structures that cannot be
seen with the naked eye
➔ can only be seen through a microscope
◆ Cytology = study of cells
◆ Histology = study of tissues
3. Developmental anatomy
➔ study the growth and development,
changes that happen in our body as we
grow.
➔ includes fetal growth and as we grow
older.
➔ traces structural changes throughout the
life
◆ Fetal growth
◆ Body changes
Embryology – study of the developmental
changes of the body before birth
(prenatal development)
Anatomy and Physiology 1
4. Pathological anatomy
➔ Concerned with structural changes in
both macroscopic and microscopic that
are associated with disease.
➔ studies the morphology, development,
causes and effects of organ, tissue and
cell alterations produced by diseases,
both innate and acquired, and by
traumatic injuries, both accidental and
provoked.
5. Imaging anatomy (Anatomical Imaging)
➔ uses radiographs (x-rays), ultrasound,
magnetic resonance imaging (MRI), and
other technologies to create pictures of
internal structures
➔ This allows medical personnel to look
inside the body with amazing accuracy
and without the trauma and risk of
exploratory surgery
➔ In
1895,
Wilhelm
Roentgen
(1845–1923) became the first medical
scientist to use x-rays to see inside the
body.
➔ The rays were called x-rays because no
one knew what they were.
➔ Whenever the human body is exposed to
x-rays,
ultrasound, electromagnetic
fields,
or
radioactively
labeled
substances, a potential risk exists. This
risk must be weighed against the
medical benefit.
➔ The risk of anatomical imaging is
minimized by using the lowest possible
doses
providing
the
necessary
information.
➔ No known risks exist from ultrasound or
electromagnetic fields at the levels used
for diagnosis.
Systemic Anatomy and Regional Anatomy
- the two basic approaches to the study
of anatomy
Surface Anatomy and Anatomical Imaging
- the two general ways to examine the
internal structures of a living person.
Table 1.1
Types of Imaging Technique
X-ray
This extremely shortwave electromagnetic radiation
(see chapter 2) moves through the body, exposing a
photographic plate to form a radiograph
(rā′dēō-graf). Bones and radiopaque dyes absorb the
rays and create underexposed areas that appear
white on the photographic film. Many of us have had
an X-ray, either to visualize a broken bone or at the
dentist. However, a major limitation of radiographs is
that they give only flat, two-dimensional (2-D)
images of the body.
Ultrasound
Ultrasound, the second oldest imaging technique,
was first developed in the early 1950s from World
War II sonar technology. It uses high-frequency
sound waves, which are emitted from a
transmitter-receiver placed on the skin over the area
to be scanned. The sound waves strike internal
organs and bounce back to a receiver on the skin.
Even though the basic technology is fairly old, The
most important advances in this field occurred only
after it became possible to analyze the reflected
sound waves by when a computer could be used to
analyze the pattern of reflected sound waves and
transfer. Once a computer analyzes the pattern of
sound waves, the information is transferred to a
monitor to be visualized as a sonogram (son′ō-gram)
image. One of the more recent advances in
ultrasound technology is the ability of more
advanced computers to analyze changes in position
through “real-time” movements. Among other
medical applications, ultrasound is commonly used
to evaluate the condition of the fetus during
pregnancy
Anatomy and Physiology 2
Computed Tomography (CT)
Computed tomographic (tō′mō-graf′ik) (CT) scans,
developed in 1972 and originally called
computerized axial tomographic (CAT) scans, are
computeranalyzed x-ray images. A low-intensity
x-ray tube is rotated through a 360-degree arc
around the patient, and the images are fed into a
computer. The computer then constructs the image of
a “slice” through the body at the point where the
x-ray beam was focused and rotated (a). Some
computers are able to take several scans short
distances apart and stack the slices to produce a 3-D
image of a body part (b).
important in this imaging system. Radio waves of
certain frequencies, which change the alignment of
the hydrogen atoms, then are directed at the patient.
When the radio waves are turned off, the hydrogen
atoms realign in accordance with the magnetic field.
The time it takes the hydrogen atoms to realign is
different for various body tissues. These differences
can be analyzed by computer to produce very clear
sections through the body. The technique is also very
sensitive in detecting some forms of cancer far more
readily than can a CT scan.
Positron Emission Tomography (PET)
Digital Subtraction Angiography (DSA)
Digital subtraction angiography (an-jē-og′ră-fē)
(DSA) is one step beyond CT scanning. A 3-D
radiographic image of an organ, such as the brain, is
made and stored in a computer. Then a radiopaque
dye is injected into the blood, and a second
radiographic computer image is made. The first
image is subtracted from the second one, greatly
enhancing the differences revealed by the injected
dye. These dynamic computer images are the most
common way angioplasty, is performed. Angioplasty
uses a tiny balloon to unclog an artery.
Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) directs radio
waves at a person lying inside a large
electromagnetic field. The magnetic field causes the
protons of various atoms to align (see chapter 2).
Because of the large amounts of water in the body,
the alignment of hydrogen atom protons is most
Positron emission tomographic (PET) scans can
identify the metabolic states of various tissues. This
technique is particularly useful in analyzing the
brain. When cells are active, they are using energy
The energy they need is supplied by the break down
of glucose (blood sugar). If radioactively treated
(“labeled”) glucose is given to a patient, the active
cells take up the labeled glucose. As the radioactivity
in the glucose decays, positively charged subatomic
particles called positrons are emitted. When the
positrons collide with electrons, the two particles
annihilate each other and gamma rays are given off.
The gamma rays can be detected, pinpointing the
cells that are metabolically active
1.2 PHYSIOLOGY (Study of Nature)
➔ study of how the body and its parts work or
function
➔ ology = the study
of
➔ physio = nature
➔ focus on function often in cellular level
➔ natural philosophy
➔ The major goals when studying human
physiology are to understand and predict
the body’s responses to stimuli and to
understand how the body maintains
conditions within a narrow range of values
in a constantly changing environment.
Anatomy and Physiology 3
Importance
(1) to understand and predict the body’s
responses to stimuli.
(2) to understand how the body maintains
internal conditions within a narrow range
of values in the presence of continually
changing
internal
and
external
environments.
Human Physiology
➔ the scientific study of chemistry and
physics of the structures of the body
and the ways in which they work
together to support the functions of
life.
➔ study of a specific organism, the
human body
Subdivision of Human Physiology
➢ Cell/Cellular Physiology
➢ Special Physiology
➢ Systemic Physiology
➢ Pathophysiology
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1. Cell/Cellular Physiology
cornerstone of human physiology
study of the functions of cells
2. Special Physiology
study of the functions of specific
organs
ex: renal physiology - study of kidney
functions
3. Systemic Physiology
study the functions of the body’s organ
system
ex: respiratory system
4. Pathophysiology
study of the effects of diseases on
organ or system function
pathos - greek word for Disease
emphasis
on
the
cause
and
development of abnormal conditions
and structural and functional changes
resulting from the disease
Relationship Between Anatomy and
Physiology
➔ They are always related and inseparable
➔ They will always correlate with each
other anatomy being the study of the
actual physical organs and their
structure as well as their relationship to
each other. While physiology studies
how those organs work to function the
whole body as organ systems.
➔ For example, the lungs are not muscular
chambers like the heart and can not pump
blood, but because the walls of lungs are
very thin, they can exchange gasses and
provide oxygen to the body.
Assess Your Progress
1. How does the study of anatomy differ from
the study of physiology?
2. What is studied in gross anatomy? In surface
anatomy?
3. What type of physiology is employed when
studying the endocrine system?
4. Why are anatomy and physiology normally
studied together?
1.3 Structural and Functional
Organization of the Human Body
The body can be studied at 6 structural levels
1. Chemical/Atomic Level
2. Cell Level
3. Tissue Level
4. Organ Level
5. Organ system
6. Organism Level
The simplest level of organization in the
human body is the atom. Atoms combine to
form molecules. Molecules aggregate into cells.
Cells form tissues, which combine with other
tissues to form organs. Organs work in groups
called organ systems. All organ systems work
together to form an organism.
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1. Chemical/ Atomic Level
The
chemical
level
involves
interactions between atoms. Atoms
combine to form molecules, such as
water, sugar, lipids, and proteins
Atoms - building blocks of matter
Smallest unit of element
Chemical makeup - determines
structural
and
functional
characteristics of all organisms
Important:
molecules
structure
determine its function
For example, collagen molecules are strong,
ropelike fibers that give skin structural
strength and flexibility. With old age, the
structure of collagen changes, and the skin
becomes fragile and more easily torn during
everyday activities.
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2. Cell Level
basic structural and functional unit of
organisms (plants and animals)
Basic unit of life
Smallest unit of life
Anatomy and Physiology 4
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Molecules combine to form organelles
(little organ), which are the small
structures that make up cells
For example, the nucleus contains the cell’s
hereditary information, and mitochondria
manufacture adenosine triphosphate (ATP), a
molecule cells use for a source of energy.
Although cell types differ in their structure
and function, they have many characteristics
in
common.
Knowledge
of
these
characteristics and their variations is essential
to a basic understanding of anatomy and
physiology.
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3. Tissue Level
Consists of similar types of cells and
the materials surrounding them.
Characteristics
of
cells
and
surrounding materials determine the
function of tissue.
The body is made up of
Four Primary Types
➔ Epithelial tissue covers body
surfaces, lines hollow organs
and cavities, and forms glands.
➔ Connective tissue connects,
supports, and protects body
organs
while
distributing
blood vessels to other tissues.
➔ Muscular tissue contracts to
make body parts move and
generates heat.
tissue
carries
➔ Nervous
information from one part of
the body to another through
nerve impulses.
For example, the urinary system consists of
the kidneys, ureters, urinary bladder, and
urethra. The kidneys produce urine, which is
transported by the ureters to the urinary
bladder, where it is stored until eliminated
from the body by passing through the urethra.
For example, the digestive system takes in
food, processing it into nutrients that are
carried by the blood of the cardiovascular
system to the cells of the other systems. These
cells use the nutrients and produce waste
products that are carried by the blood to the
kidneys of the urinary system, which removes
waste products from the blood. Because the
organ systems are so interrelated, dysfunction
in one organ system can have profound effects
on other systems. For example, a heart attack
can result in inadequate circulation of blood.
Consequently, the organs of other systems,
such as the brain and kidneys, can
malfunction.
11 Major Organ System
➢ Integumentary
➢ Skeletal
➢ Muscular
➢ Nervous
➢ Endocrine
➢ Cardiovascular
➢ Lymphatic
➢ Respiratory
➢ Digestive
➢ Urinary
➢ Reproductive
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4. Organ Level
Composed of two or more tissue types
that perform common functions
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Examples of some of our organs include the
heart, stomach, liver, and urinary bladder
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5. Organ System Level
Group of organs classified as a unit
because of a common function or set of
functions
Coordinated activity of the organ
system is necessary for normal
function
6. Organism Level
Several organ systems that function
together in order to form one
organism
Any living thing considered as a whole
Whether composed of one cell
(bacterium) or trillions of cells
(human)
Human organism is a complex of organ
system that are mutually dependent
upon one another
Assess Your Progress:
5. From simplest to complex, list and define
the body’s six levels of organization.
6. What are the four basic types of tissues?
7. Referring to figure 1.3, which two organ
systems are responsible for regulating the
other organ systems? Which two are
responsible for support and movement?
Anatomy and Physiology 5
Figure 1.1 Levels of Organization in the Human Body
Figure 1.2 Major Organs of the Body
Anatomy and Physiology 6
Figure 1. 3 11 Organ System Level
1. Integumentary System (skin)
Produces oocytes and is the site of
fertilization and fetal development; produces
milk for the newborn; produces hormones
that influence sexual function and behaviors.
Consists of the ovaries, uterine tubes, uterus,
vagina, mammary glands, and associated
structures.
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It waterproofs the body and protects
deeper tissues from injury. Provides
protection and prevents water loss.
Produces vitamin d (7AM to 9 am)
Forms the external body covering
Excretes salts in perspiration and
helps regulate body temperature.
Location of the cutaneous receptors
(pain, pressure, etc.), sweat and oil
glands
Senses changes in the body
Stores fat and provides insulation
Consists of skin, hair, nails, sebaceous
glands and sweat glands.
2. Reproductive system
● Production of offspring
● Secretes hormones
● Testes produce sperm and male sex
hormone; ducts and glands aid in
delivery of viable sperm to the female
reproductive tract.
● Ovaries produce eggs and female sex
hormones; remaining structures serve
as
sites
for fertilization and
development of the fetus. Mammary
glands of female breasts produce milk
to nourish the newborn.
Male Reproductive System
Produces and transfers sperm cells to the
female and produces hormones that
influence sexual functions and behaviors.
Consists of the testes, accessory structures,
ducts, and penis.
3. Urinary system
Female Reproductive System
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Releases nitrogenous waste of the
body
Maintain acid-base balance of the body
Regulates water, electrolyte, and
acid-base balance of the blood
Removes waste products from the
blood and regulates blood pH, ion
balance, and water balance.
Consists of the kidneys, urinary
bladder, and ureters.
Anatomy and Physiology 7
4. Respiratory system
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Exchanges oxygen and carbon dioxide
between the blood and air and
regulates blood pH.
Keeps blood constantly supplied with
oxygen and removes co2
The nasal passages, pharynx, larynx,
trachea, bronchi, and lungs
6. Lymphatic System
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5. Digestive System
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Removes foreign substances from the
blood and lymph, combats disease,
maintains tissue fluid balance, and
absorbs dietary fats from the digestive
tract.
Complements
the
cardiovascular
system
Lymphatic vessels, lymph nodes and
other lymphoid organs such as sleep
and tonsils
Picks up fluid leaked from blood
vessels and returns it to blood
Houses of WBC for immunity
Involves
basophils,
eosinophils,
neutrophils
Disposes of debris
Consists of the lymphatic vessels,
lymph nodes, and other lymphatic
organs.
7. Endocrine System
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Breakdown of foods into absorbable
nutrients that enter the blood for
distribution to body cells; indigestible
foodstuffs are eliminated as feces.
Small intestine: contains villi which
aids in digestion and absorption of
nutrients needed by the body
The organs of the digestive system
include the oral cavity (mouth),
esophagus, stomach, small and large
intestines, and rectum
Accessory organs (liver, salivary
glands, pancreas, and others)
Performs the mechanical and chemical
processes of digestion, absorption of
nutrients, and elimination of wastes.
Consists of the mouth, esophagus,
stomach, intestines, and accessory
organs.
Anatomy and Physiology 8
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Consists of endocrine glands, such as
the pituitary, that secrete hormones.
Gland secrete hormones that regulate
processes
such
as
growth,
reproduction and nutrient use of the
body cells.
Glands
Pituitary
Pineal
Thyroid
Hormones
Produced
Adrenocorticotropic
and
growth
hormone
Melatonin
Growth hormone and
metabolism
Thymus
Production of t-cells
Adrenal
Adrenaline (cortisol
and aldosterone)
Testes
Testosterone
Ovary
Pancreas
9. Nervous system
Estrogen
and
progesterone
Degrades
macromolecules
8. Circulatory system or cardiovascular
system
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A major regulatory system that detects
sensations and controls movements,
physiological
processes,
and
intellectual functions.
Consists of the brain, spinal cord,
nerves, and sensory receptors
Activates muscles and glands
Main control system of the body
Fast acting control system of the body
Responses to the environment
(fight/flight response)
- The sensory receptors detect
changes
in
temperature,
pressure, or light, and send
messages (via electrical signals
called nerve impulses) to the
central nervous system (brain
and spinal cord)
- The central nervous system
then assesses this information
and responds by activating the
appropriate body effectors
(muscles or glands, which are
organs
that
produce
secretions).
10. Muscular system
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Transports nutrients, waste products,
gasses, and hormones throughout the
body
Plays a role in the immune response
and
the
regulation
of
body
temperature.
Consists of the heart, blood vessels,
and blood.
Oxygen: utilized in respiratory
(aerobic: 36 ATP, anaerobic: 2 ATP)
Anatomy and Physiology 9
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Produces body movements, maintains
posture and facial expression, and
produces body heat.
Consists of muscles attached to the
skeleton by tendons
Formed by the skeletal muscles
Allows manipulation of environment
11. Skeletal system
1.4 Essential Characteristics of Life (Basic)
Humans
are
organisms
sharing
characteristics with other organisms. The
most important common feature of all
organisms is life.
1. Organization
2. Metabolism
3. Responsiveness
4. Growth
5. Development
6. Reproduction
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Provides protection and support to
body organs
Allows body movements and provides
a framework that the skeletal muscles
use to cause movement
Produces blood cells that are formed
in bones
- Site of blood cell formation
(hematopoiesis)
- Stores minerals and adipose
tissue in the form of calcium
- Consists of bones, associated
cartilages,
ligaments,
and
joints.
- Tendons: bone to muscle
- Joints: bone to bone
- Cartilage: rubber-like pudding,
elastic connective tissue
- Ligaments: made out of
connective tissue that has a lot
of strong collagen fibers in it
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1. Organization
Specific relationship of the many
individual parts of an organism, from
cell organelles to organs, interacting
and working together
Highly organized structure
Follows hierarchy
All organisms are composed of one or
more cells.
Some cells, in turn, are composed of
highly specialized organelles, which
depend on the precise functions of
large molecules.
Disruption of this organized state can
result in loss of function and death.
2. Metabolism
Ability to use energy to perform vital
functions, such as growth, movement,
and reproduction.
Plants capture energy from sunlight to
synthesize sugars (a process called
photosynthesis), and humans obtain
energy from food.
Anabolism
- process
where
simple
molecules are gathered to
create complex molecules
- storing/building of energy
- smaller to larger
Catabolism
- process
where
complex
molecules were broken down
of energy
- breaking down of energy
- larger to smaller
3. Responsiveness
The ability of an organism to adjust to
changes in its internal and external
environments and adjust to those
changes..
Ability to sense and react to a certain
stimulus and changes from both
internal and external
Anatomy and Physiology 10
Example: Changes in an organism’s internal
environment, such as increased body
temperature, can cause the responses of
sweating and the dilation of blood vessels in
the skin in order to decrease body
temperature. Or the movements toward food
or water and away from danger or poor
environmental conditions such as extreme
cold or heat.
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4. Growth
An increase in the size or number of
cells, which produces an overall
enlargement of all or part of an
organism.
Can result from an increase in cell
number, cell size, or the amount of
substance surrounding cells.
Example, bones grow when the
number of bone cells increases and the
bone cells become surrounded by bone
matrix
○ Bone Matrix (osteoid)
■ helps to strengthen the
bone structure
■ consists of about 33%
organic matter (mostly
Type I collagen) and
67% inorganic matter
(calcium
phosphate,
mostly hydroxyapatite
crystals).
5. Development
The changes an organism undergoes
through time (fertilization - death)
Development usually involves growth,
but it also involves differentiation and
morphogenesis.
Differentiation - change in cell structure and
function from immature (generalized) to a
mature (specialized) state. Also includes the
processes of growth and repair, both of which
involve cell differentiation. - knowledge, IQ
and EQ
For example, following fertilization, immature
cells differentiate to become specific cell types,
such as skin, bone, muscle, or nerve cells.
These differentiated cells form tissues and
organs.
Morphogenesis is the change in shape of
tissues, organs, and the entire organism
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6. Reproduction
formation of a new cell or new
organism from parent organisms.
In humans, reproduction is carried out
by the male and female reproductive
systems. Because death will come to all
complex
organisms,
without
reproduction, the line of organisms
would end.
Without reproduction of cells, growth
and tissue repair are impossible.
Without reproduction of the organism,
the species becomes extinct
Sexual = copulation; with the use of
sex organs. 2 parents supply DNA.
Male and female reproductive system
Asexual = absence of sexual act
pollination, cross pollination
Assess Your Progress
8. What are the six characteristics of living
things? Briefly explain each.
9. How does differentiation differ from
morphogenesis?
Maintaining life / Necessary Life Functions
(base on trans, not on Seeley book)
1. Maintaining Boundaries - our body
“inside” must remain distinct from its
“outside.”
2. Movement - all the activities promoted by
the muscular system
3. Responsiveness/sensitivity/irritability the ability to sense changes (stimuli) in the
environment and then to react to them
4. Digestion - the process of breaking down
ingested food into simple molecules that can
then be absorbed into the blood
5. Metabolism - a broad term that refers to all
chemical reactions that occur within the body
and all of its cells
● Catabolism, the breakdown of
complex chemical substances into
simpler components.
● Anabolism the building up of complex
chemical substances from smaller,
simpler components. For example,
digestive processes catabolize (split)
proteins in food into amino acids.
These amino acids are then used to
anabolize (build) new proteins that
make up body structures such as
muscles and bones.
Anatomy and Physiology 11
6. Excretion - the process of removing
excreta, or wastes, from the body
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7. Reproduction - the production of offspring,
can occur on the cellular or organismal level
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8. Growth - can be an increase in cell size or an
increase in body size that is usually accomplished
by an increase in the number of cells
9. Development - includes the changes an
organism undergoes through time, beginning with
fertilization and ending at death.
● Differentiation: the development of a cell
from an unspecialized to a specialized state.
Such precursor cells, which can divide and
give
rise
to
cells that undergo
differentiation, are known as stem cells
● Morphogenesis: is the change in shape of
tissues, organs, and the entire organism.
10. Respiration - obtaining oxygen, removing
carbon dioxide, and releasing energy from foods
(some forms of life do not use oxygen in
respiration.)
11. Absorption - passage of substances through
membranes and into body fluids
12. Circulation - movement of substances in body
fluids
13. Assimilation - changing absorbed substances
into chemically different forms
Survival needs
1. Nutrients
● Chemicals needed for energy and cell
building
major
● Carbohydrates:
energy-providing fuel for body cells
● Proteins
● Lipids: essential for building cell
structures
● Minerals and vitamins: required for
the chemical reactions that go in cells
and for oxygen transport in the blood.
2. Oxygen
● Required for chemical reactions
(main)
● Composes 20% of air in the
atmosphere
3. Water
● 60 to 80% of body weight
● Provides metabolic reaction
● The most abundant chemical in the
body.
Carries
substances
within
the
organism and is important in
regulating body temperature
Water inside the cells, along with
substances dissolved in it, constitutes
the intracellular fluid. Similarly,
outside of the cells, including the
tissue fluid and the liquid portion of
the blood (plasma), is the extracellular
fluid
4. Stable body temperature
● 37° Celsius or 99° Fahrenheit
5. Atmospheric pressure must be
appropriate
● At high altitudes, where the air is thin
and atmospheric pressure is lower, gas
exchange may be too slow to support
cellular metabolism.
addition,
organisms
living
● In
underwater
are
subjected
to
hydrostatic pressure—a pressure a
liquid exerts— due to the weight of
water above them. In humans, heart
action produces blood pressure
(another form
of hydrostatic pressure), which forces
blood to flow through blood vessels.
1.5 Biomedical Research
Studying other organisms has increased our
knowledge about humans because humans
share many characteristics with other
organisms.
For
example,
studying
single-celled
bacteria
provides much
information about human cells. However,
some biomedical research cannot be
accomplished using single-celled organisms
or isolated cells. Sometimes other mammals
must be studied, as evidenced by the great
progress in open heart surgery and kidney
transplantation made possible by perfecting
surgical techniques on other mammals
before attempting them on humans. Strict
laws govern the use of animals in biomedical
research; these laws are designed to ensure
minimal suffering on the part of the animal
and
to
discourage
unnecessary
experimentation.
Although much can be learned from studying
other organisms, the ultimate answers to
questions about humans can be obtained
only from humans because other organisms
differ from humans in significant ways. A
failure to appreciate the differences between
humans and other animals led to many
misconceptions by early scientists. One of the
first great anatomists was a Greek physician,
Anatomy and Physiology 12
Claudius Galen (ca. 130–201). Galen
described a large number of anatomical
structures supposedly present in humans but
observed only in other animals. For example,
he described the liver as having five lobes.
This is true for rats, but not for humans, who
have four-lobed livers. The errors introduced
by Galen persisted for more than 1300 years
until a Flemish anatomist, Andreas Vesalius
(1514–1564), who is considered the first
modern anatomist, carefully examined
human cadavers and began to correct the
textbooks. This example should serve as a
word of caution: Some current knowledge in
molecular biology and physiology has not
been confirmed in humans.
Assess Your Progress:
10. Why is it important to recognize that
humans share many, but not all, characteristics
with other animals?
MICROBES In Your Body
Did you know that you have more microbial
cells than human cells in your body?
Astoundingly, for every cell in your body, there
are 10 microbial cells. That’s as many as 100
trillion microbial cells, which can collectively
account for between 2 and 6 pounds of your
body weight! A microbe is any living thing
that cannot be seen with the naked eye (for
example, bacteria, fungi, and protozoa). The
total population of microbial cells on the
human body is referred to as the microbiota,
while the combination of these microbial cells
and their genes is known as the microbiome.
The microbiota includes so-called good
bacteria, which do not cause disease and may
even help us. It also includes pathogenic, or
“bad,” bacteria.
With that many microbes in and on our
bodies, you might wonder how they affect our
health. To answer that question, in October
2007 the National Institutes of Health (NIH)
initiated the 5-year Human Microbiome
Project, the largest study of its kind. Five
significant regions of the human body were
examined:
the
airway,
skin,
mouth,
gastrointestinal tract, and vagina. This project
identified over 5000 species and sequenced
over 20 million unique microbial genes
What did scientists learn from the Human
Microbiome Project? Human health is
dependent upon the health of our microbiota,
especially the “good” bacteria. In fact, it seems
that our microbiota are so completely
intertwined with human cells that it has been
suggested that humans are like corals. Corals
are marine organisms that are collections of
different life forms, all existing together. More
specifically, the human microbiome is
intimately involved in the development and
maintenance of the immune system. And more
evidence is mounting for a correlation
between a host’s microbiota, digestion, and
metabolism. Researchers have suggested that
microbial genes are more responsible for our
survival than human genes. There are even a
few consistent pathogens that are present
without causing disease, suggesting that their
presence may be good for us. However, there
does not seem to be a universal healthy human
microbiome. Rather, the human microbiome
varies across lifespan, ethnicity, nationality,
culture, and geographic location. Instead of
being a detriment, this variation may actually
be very useful for predicting disease. There
seems to be a correlation between
autoimmune and inflammatory diseases
(Crohn’s disease, asthma, multiple sclerosis),
which have become more prevalent, and a
“characteristic microbiome community.” Early
research seems to indicate that any significant
change in the profile of the microbiome of the
human gut may increase a person’s
susceptibility to autoimmune diseases. It has
been proposed that these changes may be
associated with exposure to antibiotics,
particularly in infancy. Fortunately, newer
studies of microbial transplantations have
shown that the protective and other functions
of bacteria can be transferred from one person
to the next. However, this work is all very new,
and much research remains to be done.
1.6 Homeostasis
(homeo- the same; -stasis, to stop)
● The existence and maintenance of a
relatively constant environment within
the body despite fluctuations in either
the external environment or the
internal environment.
● The internal environment of the body
is in a dynamic state of equilibrium
(balance)
● Chemical, thermal and neural factors
interact to maintain homeostasis.
● Our body has a set temperature. It
detects if the environment is too hot or
too cold, it will also make mechanisms
for it to maintain the temperature
inside.
● It is achieved when structures and
functions are properly coordinated.
● The entire regulation process of
homeostasis is made possible by the
coordinated action of many organs and
tissues under the control of the
nervous and endocrine systems.
Anatomy and Physiology 13
●
●
●
note that when homeostasis breaks
down, we become sick or die.
disturbance = homeostatic imbalance
Importance: survival
Most body cells are surrounded by a small
amount of fluid, and normal cell functions
depend on the maintenance of the cells’ fluid
environment within a narrow range of
conditions , including temperature, volume,
and chemical content. These conditions are
called variables because their values can
change.
To achieve homeostasis, the body must
actively regulate conditions that are constantly
changing. As our bodies undergo their
everyday processes, we are continuously
exposed to new conditions. These conditions
are called variables.
Variables
● Because their values can change.
● One familiar variable is body
temperature, which can increase when
the environment is hot or decrease
when the environment is cold.
Homeostatic mechanisms
- Such as sweating or shivering,
normally maintain body temp near an
ideal normal value or set point.
- Controlled by the nervous system or
the endocrine system
- Note that homeostatic mechanisms are
not able to maintain body temperature
precisely at the set point. Instead, body
temperature increases and decreases
slightly around the set point,
producing a normal range of values. As
long as body temperatures remain
within this normal range, homeostasis
is maintained.
Set point
- ideal value
Normal range
- acceptable range of values on which
HM can still be met
Figure 1.4 Homeostasis
Homeostasis is the maintenance of a variable,
such as body temperature, around an ideal
normal value, or set point. The value of the
variable fluctuates around the set point to
establish a normal range of values
Our average body temperature is 98.6 degrees
Fahrenheit. Just as your home’s thermostat
does not keep the air temperature exactly at
75 degrees Fahrenheit at all times, your body’s
temperature does not stay perfectly stable.
The organ systems help control the internal
environment so that it remains relatively
constant. For example, the digestive,
respiratory, cardiovascular, and urinary
systems function together so that each cell in
the body receives adequate oxygen and
nutrients and so that waste products do not
accumulate to a toxic level. If the fluid
surrounding cells deviates from homeostasis,
the cells do not function normally and may
even die. Disease disrupts homeostasis and
sometimes results in death.
●
●
Feedback Mechanisms
Negative - Feedback - Mechanism
Positive - Feedback - Mechanism
Negative Feedback
➔ Regulates most systems of the body
which maintain homeostasis.
➔ The word negative is used to mean
“bad” or “undesirable.” In this context,
negative means “to decrease.”
➔ Shuts off the original stimulus or
reduces its intensity
➔ Negative feedback is when any
deviation from the set point is made
smaller or is resisted. Negative
feedback does not prevent variation
but maintains variation within a
normal range
The maintenance of normal body temperature
is an example of a negative-feedback
mechanism. Normal body temperature is
important because it allows molecules and
enzymes to keep their normal shape so they
can function optimally. An optimal body
temperature prevents molecules from being
permanently destroyed. Picture the change in
appearance of egg whites as they are cooked;
Similarly, if the body is exposed to extreme
heat, the shape of the molecules in the body
could change, which would eventually prevent
them from functioning normally. Thus, normal
body temperature is required to ensure that
tissue homeostasis is maintained.
Anatomy and Physiology 14
Most negative-feedback mechanisms have
Three Components:
● Receptor - monitors the value of a
variable, such as body temperature, by
detecting stimuli
● Control Center - such as part of the
brain, determines the set point for the
variable and receives input from the
receptor about the variable
● Effector - such as the sweat glands,
can change the value of the variable
when directed by the control center. A
changed variable is a stimulus because
it initiates a homeostatic mechanism.
Normal body temperature depends on the
coordination of multiple structures, which are
regulated by the control center, or
hypothalamus, in the brain. If body
temperature rises, sweat glands (the effectors)
produce sweat and the body cools. If body
temperature falls, sweat glands do not
produce sweat (figure 1.5). The stepwise
process that regulates body temperature
involves the interaction of receptors, the
control center, and effectors. Often, there is
more than one effector and the control center
must integrate them.
In the case of elevated body temperature,
thermoreceptors
in
the
skin
and
hypothalamus detect the increase in
temperature and send the information to the
hypothalamus control center. In turn, the
hypothalamus stimulates blood vessels in the
skin to relax and sweat glands to produce
sweat, which sends more blood to the body’s
surface for radiation of heat away from the
body. The sweat glands and skin blood vessels
are the effectors in this scenario. Once body
temperature returns to normal, the control
center signals the sweat glands to reduce
sweat production and the blood vessels
constrict to their normal diameter. On the
other hand, if body temperature drops, the
control center does not stimulate the sweat
glands. Instead, the skin blood vessels
constrict more than normal and blood is
directed to deeper regions of the body,
conserving heat in the interior of the body. In
addition, the hypothalamus stimulates
shivering, quick cycles of skeletal muscle
contractions, which generates a great amount
of heat. Again, once the body temperature
returns to normal, the effectors stop. In both
cases, the effectors do not produce their
responses indefinitely and are controlled by
negative feedback. Negative feedback acts to
return the variable to its normal range (figure
1.6).
Although homeostasis is the maintenance of a
normal range of values, this does not mean
that all variables remain within the same
narrow range of values at all times. Sometimes
a deviation from the usual range of values can
be beneficial. For example, during exercise the
normal range for blood pressure differs from
the range under resting conditions and the
blood pressure is significantly elevated (figure
1.7). Muscle cells require increased oxygen
and nutrients and increased removal of waste
products to support their heightened level of
activity during exercise. Elevated blood
pressure increases delivery of blood to
muscles during exercise, thereby increasing
the delivery of oxygen and nutrients and the
removal of waste products—ultimately
maintaining muscle cell homeostasis
Components Homeostatic Control System
1. Receptors - Responds to environmental
changes via to stimulus (Change in
environment)
2. Afferent - Delivers the information from the
receptors to the control center
3. Control Center - Gives out the response.
Maintains and analyses information
4. Efferent - Delivers the response from the
Control. Center to the Effector
5. Effector - Response to stimulus
PROCESS Figure 1.5 Negative-Feedback
Mechanism: Body Temperature
1. Receptors monitor the value of a
variable. In this case, receptors in the
skin monitor body temperature.
2. Information about the value of the
variable is sent to a control center. In
this case, nerves send information to
the part of the brain responsible for
regulating body temperature.
3. The control center compares the value
of the variable against the set point.
Anatomy and Physiology 15
4. If a response is necessary to maintain
homeostasis, the control center causes
an effector to respond. In this case,
nerves send information to the sweat
glands.
5. An effector produces a response that
maintains homeostasis. In this case,
stimulating sweat glands lowers body
temperature.
Case Study: Orthostatic Hypotension
Molly is a 75-year-old widow who lives alone. For
2 days, she had a fever and chills and mainly
stayed in bed. On rising to go to the bathroom,
she felt dizzy, fainted, and fell to the floor. Molly
quickly regained consciousness and managed to
call her son, who took her to the emergency
room, where a physician diagnosed orthostatic
hypotension.
Orthostasis literally means “to stand,” and
hypotension refers to low blood pressure; thus,
orthostatic hypotension is a significant drop in
blood pressure upon standing. When a person
moves from lying down to standing, blood “pools”
within the veins below the heart because of
gravity, and less blood returns to the heart.
Consequently, blood pressure drops because the
heart has less blood to pump
Although orthostatic hypotension has many
causes, in the elderly it can be due to age-related
decreases in neural and cardiovascular
responses. Decreased fluid intake while feeling ill
and sweating due to a fever can result in
dehydration. Dehydration can decrease blood
volume and lower blood pressure, increasing the
likelihood of orthostatic hypotension.
a. Describe the normal response to a
decrease in blood pressure on standing.
b. What happened to Molly’s heart rate just
before she fainted? Why did Molly faint?
c. How did Molly’s fainting and falling to the
floor help establish homeostasis
(assuming she was not injured)?
CLINICAL IMPACT
Humors and Homeostasis
The idea that the body maintains a balance
(homeostasis) can be traced back to ancient
Greece. Early physicians believed that the
body supported four fluids, or humors: blood,
bile, mucus from the nose and lungs, and a
black fluid in the pancreas. They also thought
that an excess of any one humor caused
disease. They believed the body healed itself
by expelling the excess fluids, such as with a
runny nose. This belief led to the practice of
bloodletting to restore the body’s normal
balance of humors. Physicians would puncture
larger, external vessels, or use leeches, blood
eating organisms. Unfortunately, bloodletting
went to extremes and barbers conducted the
actual procedure. In fact, the traditional
red-and-white-striped barber pole originated
as a symbol for bloodletting. The brass basin
on top of the pole represented the bowl for
leeches, and the bowl on the bottom
represented the basin for collecting blood. The
stripes represented bandages used as
tourniquets, and the pole itself stood for the
wooden staff patients gripped during the
procedure. The fact that bloodletting did not
improve the patient’s condition was taken as
evidence that still more blood should be
removed, undoubtedly causing many deaths.
Eventually, the practice was abandoned. The
modern term for bloodletting is phlebotomy
(fle-bot′o --me- ), but it is practiced in a
controlled setting and removes only small
volumes of blood, usually for laboratory
testing. There are some diseases in which
bloodletting is still useful—for example,
polycythemia, an overabundance of red blood
cells.
Anatomy and Physiology 16
Homeostasis Figure 1.6 Negative-Feedback
Control of Body Temperature
The changes caused by the increase of a
variable outside the normal range are shown
in the green boxes, and the changes caused by
a decrease are shown in the red boxes. To help
you learn how to interpret homeostasis
figures, some of the steps in this figure are
numbered.
1. Body temperature is within its normal
range.
2. Body temperature increases outside
the normal range, which causes
homeostasis to be disturbed.
3. The body temperature control center
in the brain responds to the change in
body temperature.
4. The control center causes sweat glands
to produce sweat and blood vessels in
the skin to dilate.
5. These
changes
cause
body
temperature to decrease.
6. Body temperature returns to its
normal range, and homeostasis is
restored.
Observe the responses to a decrease in body
temperature outside its normal range by
following the red arrows.
Anatomy and Physiology 17
Positive Feedback Mechanism
➔ occur when a response to the original
stimulus results in the deviation from
the set point becoming even greater.
➔ In other words, positive means that
the deviation from the set point
becomes even greater. In this case, the
word “positive” indicates an increase.
➔ Only occurs during blood clotting and
childbirth.
➔ At times, this type of response is
required to re-achieve homeostasis.
For example, during blood loss, a chemical
responsible for clot formation stimulates
production of itself. In this way, a disruption in
homeostasis
is
resolved
through
a
positive-feedback mechanism. What prevents
the entire vascular system from clotting? The
clot formation process is self-limiting.
Eventually, the components needed to form a
clot will be depleted in the damaged area and
more clot material cannot be formed (figure
1.7).
Birth is another example of a normally
occurring positive feedback mechanism. Near
the end of pregnancy, the uterus is stretched
by the baby’s large size. This stretching,
especially around the opening of the uterus,
stimulates contractions of the uterine muscles.
The uterine contractions push the baby
against the opening of the uterus, stretching it
further.
This
stimulates
additional
contractions, which result in additional
stretching. This positive-feedback sequence
ends when the baby is delivered from the
uterus and the stretching stimulus is
eliminated.
effect, the heart pumps blood to itself. Just as
with other tissues, blood pressure must be
maintained to ensure adequate delivery of
blood to the cardiac muscle. Following
extreme blood loss, blood pressure decreases
to the point that the delivery of blood to
cardiac muscle is inadequate. As a result,
cardiac muscle homeostasis is disrupted, and
cardiac muscle does not function normally.
The heart pumps less blood, which causes the
blood pressure to drop even lower. The
additional decrease in blood pressure further
reduces blood delivery to cardiac muscle, and
the heart pumps even less blood, which again
decreases the blood pressure. The process
continues until the blood pressure is too low
to sustain the cardiac muscle, the heart stops
beating, and death results. Following a
moderate amount of blood loss (e.g., after
donating a pint of blood), negative-feedback
mechanisms result in an increase in heart rate
that restores blood pressure.
However,
if
blood
loss
is
severe,
negative-feedback mechanisms may not be
able to maintain homeostasis, and the
positive-feedback effect of an ever-decreasing
blood pressure can develop. A basic principle
to remember is that many disease states result
from the failure of negative-feedback
mechanisms to maintain homeostasis. The
purpose of medical therapy is to overcome
illness
by
aiding
negative-feedback
mechanisms. For example, a transfusion can
reverse a constantly decreasing blood
pressure and restore homeostasis.
Two basic principles to remember are that:
1. Many disease states result from the
failure
of
negative-feedback
mechanisms to maintain homeostasis
and
2. Some positive-feedback mechanisms
can be detrimental instead of helpful
On the other hand, occasionally a
positive-feedback
mechanism
can
be
detrimental instead of helpful.
One
example
of
a
detrimental
positive-feedback mechanism is inadequate
delivery of blood to cardiac (heart) muscle.
Contraction of cardiac muscle generates blood
pressure and moves blood through the blood
vessels to the tissues. A system of blood
vessels on the outside of the heart provides
cardiac muscle with a blood supply sufficient
to allow normal contractions to occur. In
FIGURE 1.7 Changes in Blood Pressure
During Exercise
During exercise, muscle tissue demands more
oxygen. To meet this demand, blood pressure
(BP) increases, resulting in an increase in
blood flow to the tissues. The increased blood
pressure is not an abnormal or nonhomeostatic condition but a resetting of the
normal homeostatic range to meet the
increased demand. The reset range is higher
and broader than the resting range. After
exercise ceases, the range returns to that of
the resting condition
Anatomy and Physiology 18
Figure 1.8 Comparison of Negative-feedback
and Positive-feedback Mechanisms
(a) In negative feedback, the response stops
the effector.
(b) In positive feedback, the response keeps
the reaction going. For example, during
blood clotting, the "active product"
represents thrombin, which triggers
"enzyme A," the first step in the cascade
that leads to the production of thrombin.
Assess Your Progress
11. How do variables, set points, and normal
ranges relate to homeostasis?
12. Distinguish between negative feedback
and positive feedback.
13. What are the three components of a
negative-feedback mechanism?
14.
Give
an
example
of how a
negative-feedback
mechanism
maintains
homeostasis.
15. Give an example of a positive-feedback
mechanism that may be harmful to the body
and an example of one that is not harmful.
1.7 Terminology and the Body Plan
Knowing the derivation, or etymology, of these
words can make learning them easy and fun.
Most anatomical terms are derived from Latin
or Greek. For example, anterior in Latin means
“to go before.” Therefore, the anterior surface
of the body is the one that “goes before” when
we are walking. Foramen is a Latin word for
“hole,” and magnum means “large.” The
foramen magnum is therefore a large hole in
the skull through which the spinal cord
attaches to the brain. Words are often
modified by adding a prefix or suffix. For
example, the suffix -itis means an
inflammation,
so
appendicitis
is an
inflammation of the appendix.
●
●
Language of Anatomy
Special terminologies used to prevent
misunderstanding
Exact terms are used for Position,
Direction, Regions, and Structures
Body Positions
The position of the body can affect the
description of body parts relative to each
other. In the anatomical position, the elbow is
above the hand, but in the supine or prone
position, the elbow and hand are at the same
level. To avoid confusion, relational
descriptions are always based on the
anatomical position, no matter the actual
position of the body. Thus, the chest is always
described as being “above” (superior to) the
stomach, whether the person is lying down
or is even upside down.
➔ Anatomical Position
◆ refers to a person standing
upright with the face directed
forward, the upper limbs
hanging to the sides, feet
slightly apart, and the palms of
the hands facing forward
(figure 1.9).
◆ Standard position of the body
➔ Supine Position - a person lying face
upward
➔ Prone Position - when lying face
downward.
Directional Terms
Directional terms describe parts of the body
relative to each other (figure 1.9 and table
1.2). Right and left are used as directional
terms in anatomical terminology.
1.
2.
3.
4.
5.
Superior - above, or up,
Inferior - below, or down.
Anterior - front, goes before
Posterior - back, that which follows
Ventral - means belly. Therefore, the
anterior surface of the human body
can also be called the ventral surface,
because the belly “goes first” when we
are walking.
6. Dorsal means “back.” Thus, the
posterior surface of the body is the
dorsal surface, or back, which follows
as we are walking.
7. Proximal - nearest, closer to point of
attachment
8. Distal - distant, far, farther from point
of attachment
These terms are used to refer to linear
structures, such as the limbs, in which one end
is near another structure and the other end is
farther away. Each limb is attached at its
proximal end to the body, and the distal end,
such as the hand, is farther away.
9. Medial - toward the midline
10. Lateral - away from the midline.
Anatomy and Physiology 19
○
The nose is located in a medial
position on the face, and the
ears are lateral to the nose.
○ Ipsilateral - same side
○ Contralateral - opposite side
11. Intermediate - Between more medial
and lateral structures, In-between
(compares 3 parts)
12. Superficial - a structure close to the
surface of the body (External)
13. Deep - toward the interior of the body,
away from the body surface (internal)
○ For example, the skin is
superficial to muscle and bone.
Examples of Using Directional Terms
1. The forehead is SUPERIOR to the nose
2. The kidneys are INFERIOR to the lungs
3. The breastbone is ANTERIOR to the spinal
cord
4. The kidneys are POSTERIOR to the liver
5. The ears are MEDIAL to the eyes
6. The arms are LATERAL to the chest
7. The elbow is INTERMEDIATE between the
shoulder and the wrist
8. The femur is PROXIMAL to the tibia
9. The fibula is DISTAL to the patella
10. The skin is SUPERFICIAL to the muscle
11. The dermis is DEEP to the epidermis
12. The left lung is CONTRALATERAL to the
right kidney
Table
1.1
Directional Terms for the Human Body
Term
Etymolog
y
Right
Left
Definition*
Example
Toward
the
body’s
right
side
The right ear
The left ear
Toward
the
body’s
left side
Inferior
Superior
Lowe
r
Highe
r
Below
Above
Anterior
Posterio
r
To
go
before
Posterus,
following
Toward
front of
body
Toward
back of
body
The nose is
inferior to the
forehead
The mouth is
superior to the
chin
the
the
the
the
The teeth are
anterior to the
throat.
The brain is
posterior to the
eyes.
13. The right lung is IPSILATERAL to the right
kidney
ANATOMIC VARIABILITY
● Humans vary slightly in both external
and internal anatomy
● Overall 90% of all anatomical
structures
match
textbook
descriptions
- Nerves and Blood Vessels may be out
of place
- Small muscles may be missing
● Extreme anatomical variations are
seldom seen
Assess Your Progress
16. What is anatomical position in humans?
Why is it important?
17. What two directional terms indicate
“toward the head” in humans? What are the
opposite terms?
18. What two directional terms indicate “the
back” in humans? What are the opposite
terms?
19. Define the following directional terms and
give the term that means the opposite:
proximal, lateral, and superficial
Dorsal
Ventral
Dorsum,
back
Venter,
belly
Toward
the
back
(synonymous
with
posterior)
Toward
the
belly
(synonymous
with anterior)
The spine is
dorsal to the
breastbone.
The navel is
ventral to the
spine.
Proximal
Distal
Proximus,
nearest
di + sto, to
be distant
Closer to a
point
of
attachment
Farther from a
point
of
attachment
The shoulder is
proximal to the
elbow
The ankle is
distal to the hip.
Lateral
Medial
Latus, side
Medialis,
middle
Away from the
midline of the
body
Toward
the
middle
or
midline of the
body
The nipple is
lateral to the
breastbone
The bridge of
the nose is
medial to the
eye.
Superfici
al
Deep
Superficiali
s, surface
Deop, deep
Toward or on
the surface
Away from the
surface,
internal
The skin is
superficial
to
muscle
The lungs are
deep to the ribs.
*All directional terms refer to a human in the
Anatomy and Physiology 20
anatomical position
the arms hanging to the sides, and the palms
of the hands facing forward.
FIGURE 1.10 Body Parts and Regions
The anatomical and common (in parentheses)
names are indicated for the major parts and
regions of the body. (a) Anterior view.
Figure 1.9 Directional Terms
All directional terms are in relation to the
body in the anatomical position: a person
standing erect with the face directed forward,
Anatomy and Physiology 21
Body Parts and Regions
❖ The central region of the body
consists of the head, neck, and trunk.
➢ The trunk can be divided into
the thorax (chest), abdomen
(belly), and pelvis (hips).
❖ The upper limb is divided into the
arm, forearm, wrist, and hand.
➢ Arm extends from the shoulder
to the elbow
➢ Forearm extends from the
elbow to the wrist.
❖ The lower limb is divided into the
thigh, leg, ankle, and foot.
➢ Thigh extends from the hip to
the knee,
➢ Leg extends from the knee to
the ankle.
❖ Note that, contrary to popular usage,
the terms arm and leg refer to only a
part of the respective limb.
❖ The abdomen is often subdivided
superficially into four sections, or
quadrants,
by
two
imaginary
lines—one
horizontal and one
vertical—that intersect at the navel
(figure 1.11a). The quadrants formed
are
the right-upper, left-upper,
right-lower, and left-lower quadrants.
❖ In addition to these quadrants, the
abdomen is sometimes subdivided
into regions by four imaginary
lines—two horizontal and two vertical.
These four lines create an imaginary
tic-tac-toe figure on the abdomen,
resulting in nine regions: epigastric
right
and
left
hypochondriac,
umbilical, right and left lumbar,
hypogastric, and right and left iliac
(figure 1.11b).
❖ Clinicians use the quadrants or regions
as reference points for locating the
underlying organs.
For example, the appendix is in the right-lower
quadrant, and the pain of an acute
appendicitis is usually felt there. Pain in the
epigastric region is sometimes due to
gastroesophageal reflux disease (GERD), in
which stomach acid improperly moves into the
esophagus, damaging and irritating its lining.
Epigastric pain, however, can have many
causes and should be evaluated by a physician.
For example, gallstones, stomach or small
intestine ulcers, inflammation of the pancreas,
and heart disease can also cause epigastric
pain.
Body Landmarks
Anterior View
A. Axial Region
1. Cephalic (Head)
● Frontal
● Orbital
● Nasal
● Oral
● Mental
2. Cervical (Neck)
3. Thoracic
● Sternal
● Axillary
● Mammary
4. Abdominal
● Umbilical
5. Pelvic
● Inguinal (Groin)
6. Pubic (Genital)
B. Appendicular Region
1. Upper Limb
● Acromial
● Brachial (Arm)
● Antecubital
● Antebrachial (Forearm)
● Carpal (Wrist)
2. Manus (Hand)
● Pollex
● Palmar
● Digital
3. Lower Limb
● Coxal (Hip)
● Femoral
● Patellar
● Cural
● Fibular or Peroneal
4. Pedal (Foot)
● Tarsal (Ankle)
● Metatarsal
● Digital
● Hallux
Posterior View
A. Axial Region
1. Cephalic
● Otic
● Occipital
2. Cervical
Anatomy and Physiology 22
3. Back (Dorsal)
● Scapular
● Vertebral
● Lumbar
● Sacral
● Gluteal
● Perineal (Between anus and
external genitalia)
B. Appendicular Region
1. Upper Limb
● Acromial
● Brachial (Arm)
● Olecranal
●
● Antebrachial (Forearm)
2. Manus (Hand)
● Metacarpal
● Digital
3. Lower Limb
● Femoral
● Popliteal
● Sural
● Fibular or Peroneal
4. Pedal (Foot)
● Calcaneal
● Plantar
●
●
●
Body Sections
portions or slices of the body created
by the cut through the plane.
allow us to look at different views of
the body depending on the direction of
the cut.
Sectioning the body is a way to “look
inside” and observe the body’s
structures
Major Planes (SCT)
➔ Sagittal Plane
➔ Transverse Plane
➔ Coronal
1. Sagittal Plane
● Aka Median
● vertically through the body
● Divides body into left and right
● word sagittal literally means the “flight
of an arrow” and refers to the way the
body would be split by an arrow
passing anteriorly to posteriorly
● Midsagittal Plane (Median Plane)
○ Aka Media
○ Cuts through the midline
○ Divides body into left and right
equally
2.Coronal Plane (Frontal Plane)
● Aka Frontal Plane
● runs vertically to divide the body into
anterior (front) and posterior (back)
parts.
● Divides body into Posterior and
Anterior
Figure 1.11 Subdivisions of the Abdomen
Lines are superimposed over internal organs
to demonstrate the relationship of the organs
to the subdivisions.
(a) Abdominal quadrants consist of four
subdivisions.
(b) Abdominal regions consist of nine
subdivisions
Body Planes and Sections
●
●
Body Planes
Body planes are imaginary lines drawn
through an upright body that is in
anatomical position.
The major planes or imaginary lines
run vertically or horizontally.
3. Transverse Plane
● Aka Axial, Horizontal Plane or Cross
Section
● runs parallel to the surface of the
ground
● Divides body into Superior and
Inferior
Minor Plane
Oblique Plane orLongitudinal Plane
1. Oblique Plane
● Divides the body diagonally
● any plane that is not horizontal or
vertical.
● You can think of “Oblique” and “Odd”,
which both start with the letter “O”, to
help you remember oblique planes are
odd and travel at strange angles.
2. Longitudinal Plane
● any plane that is perpendicular to the
transverse plane
● Coronal and sagittal planes are
examples of longitudinal planes.
Anatomy and Physiology 23
Figure 1.12 Planes of Section of the Body
(a) Planes of section through the body are
indicated by “glass” sheets. Also shown are
actual sections through
(b) the head (viewed from the right),
(c) the abdomen (inferior view; liver is on the
right), and
(d) the hip (anterior view).
Anatomy and Physiology 24
Organs are often sectioned to reveal their
internal structure (figure 1.13). A cut through
the length of the organ is a longitudinal
section, and a cut at a right angle to the length
of an organ is a transverse (cross) section. If a
cut is made across the length of an organ at
other than a right angle, it is called an oblique
section.
Figure 1.13 Planes of Section Through an
Organ
Planes of section through the small intestine
are indicated by “glass” sheets. The views of
the small intestine after sectioning are also
shown. Although the small intestine is
basically a tube, the sections appear quite
different in shape.
Body Cavities
➔ A fluid-filled space inside the body that
holds and protects internal organs.
➔ Human body cavities are separated by
membranes and other structures.
➔ The two largest human body cavities
are the Ventral Cavity and the Dorsal
Cavity. These two body cavities are
subdivided into smaller body cavities.
Two Largest Human Body Cavities
➔ Ventral Cavity
➔ Dorsal Cavity
Ventral Cavity
● is at the anterior, or front, of the trunk.
● Organs contained within this body
cavity include the lungs, heart,
stomach, intestines, and reproductive
organs.
● It allows for considerable changes in
the size and shape of the organs within
it as they perform their functions.
For example, organs such as the lungs,
stomach, or uterus can expand or contract
without distorting other tissues or disrupting
the activities of nearby organs.
Subdivision of Ventral Cavity
➔ Thoracic Cavity
◆ fills the chest and is subdivided
into two pleural cavities and
the pericardial cavity.
◆ The pleural cavities hold the
lungs, and the pericardial
cavity holds the heart.
◆ surrounded by the rib cage and
is
separated
from
the
abdominal cavity by the
muscular diaphragm.
◆ It is divided into right and left
parts by a center structure
called the mediastinum
a
● Mediastinum
section that houses the
heart, the thymus, the
trachea, the esophagus,
and other structures.
The mediastinum is
between the two lungs,
which are located on
each side of the
thoracic cavity
➔ Abdominal Cavity
◆ bounded primarily by the
abdominal muscles
◆ contains the stomach, the
intestines, the liver, the spleen,
the pancreas, and the kidneys.
➔ Pelvic Cavity
◆ a small space enclosed by the
bones of the pelvis
◆ contains the urinary bladder,
part of the large intestine, and
the
internal
reproductive
organs
*** The abdominal and pelvic cavities are not
physically separated and sometimes are called
the abdominopelvic (ab-dom′i-nō-pel′vik)
cavity ***
Dorsal Cavity
- is at the posterior, or back, of the body,
including both the head and the back
of the trunk.
Subdivision of Dorsal Cavity
➔ Cranial Cavity
◆ fills most of the upper part of
the skull
◆ contains the brain.
Anatomy and Physiology 25
➔ Spinal Cavity
◆ is a very long, narrow cavity
inside the vertebral column.
◆ It runs the length of the trunk
and contains the spinal cord
cavity membranes. The part of the
balloon in contact with your fist (the
inner balloon wall) represents the
visceral (organ) serous membrane,
and the outer part of the balloon wall
represents the parietal (wall) serous
membrane (figure 1.14).
❖ Serous Fluid
➢ is a lubricating film produced
by the membranes found in the
cavity, or space, between the
visceral and parietal serous
membranes.
❖ As an organ rubs against another
organ or against the body wall, the
serous fluid and smooth serous
membranes reduce friction.
Figure 1.14 Trunk Cavities
(a) Anterior view showing the major trunk
cavities. The diaphragm separates the thoracic
cavity from the abdominal cavity. The
mediastinum, which includes the heart, is a
partition of organs dividing the thoracic cavity.
(b) Sagittal section of the trunk cavities
viewed from the left. The dashed line shows
the division between the abdominal and pelvic
cavities. The mediastinum has been removed
to show the thoracic cavity
Serous Membranes
❖ Serous membranes line the trunk
cavities and cover the organs of these
cavities.
❖ Parietal membranes are found
against the outer wall of a body cavity,
and visceral membranes are found
covering the organs in a body cavity.
❖ To understand the relationship
between serous membranes and an
organ, imagine your fist as an organ.
Now imagine pushing your fist into an
inflated balloon, which represents the
Anatomy and Physiology 26
Figure 1.15 Serous Membrane
a. Fist pushing into a balloon. A “glass” sheet
indicates the location of a cross section
through the balloon.
b. Interior view produced by the section in (a).
The fist represents an organ, and the walls of
the balloon represent the serous membranes.
The inner wall of the balloon represents a
visceral serous membrane in contact with the
fist (organ). The outer wall of the balloon
represents a parietal serous membrane.
c. View of the serous membranes surrounding
the lungs. The membrane in contact with the
lungs is the visceral pleura; the membrane
lining the wall of the lung cavity is the parietal
pleura. Figure 1.16 shows the relationship of
the parietal and visceral membranes to the
heart.
Three Serous Membrane-lined Cavities in
Thoracic Cavity
➔ 1 Pericardial Cavity
◆ (around the heart) surrounds
the heart (figure 1.15a).
➔ 2 Pleural Cavities.
➔ (4th - Abdominopelvic Cavity)
Pericardial Cavity
● (around the heart) surrounds the
heart (figure 1.16a)
● Pericardial Fluid
○ the fluid filling the pericardial
cavity
○ Found between the visceral
pericardium and the parietal
pericardium.
Pericardium or Pericardial Sac (additional
info)
➔ is a double-walled sac containing the
heart and the roots of the great
vessels.
Three Membrane Layers in Pericardium
Fibrous pericardium
◆ is the outer fibrous sac that
covers the heart.
◆ provides an outer protective
layer that is attached to the
sternum by sternopericardial
ligaments.
◆ helps keep the heart contained
within the chest cavity.
◆ protects the heart from an
infection that could potentially
spread from nearby organs
such as the lungs.
Parietal Pericardium
◆ is the layer between the
fibrous
pericardium
and
visceral pericardium.
◆ it is continuous with fibrous
pericardium and provides an
additional layer of insulation
for the heart.
Visceral Pericardium
◆ is both the inner layer of the
pericardium and the outer
layer of the heart wall.
◆ also known as the epicardium,
◆ this layer protects the inner
heart layers and also assists in
the production of pericardial
fluid.
Pleural Cavity
● (associated with the ribs) surrounds
each lung.
● Each lung is covered by visceral pleura
(figure 1.16b).
● Parietal pleura lines the inner surface
of the thoracic wall, the lateral surfaces
of the mediastinum, and the superior
surface of the diaphragm.
● Pleural cavity is located between the
visceral pleura and the parietal pleura
and contains pleural fluid.
Abdominopelvic Cavity
● Contains a serous membrane lined
cavity called the peritoneal ( to
stretch over) cavity (figure 1.16c).
● Visceral peritoneum covers many of
the organs of the abdominopelvic
cavity.
● Parietal peritoneum lines the wall of
the abdominopelvic cavity and the
inferior surface of the diaphragm.
● The peritoneal cavity is located
between the visceral peritoneum and
the parietal peritoneum and contains
peritoneal fluid.
The serous membranes can become
inflamed—usually as a result of an infection.
➢ Pericarditis is inflammation of the
pericardium,
➢ Pleurisy is inflammation of the pleura,
➢ Peritonitis is inflammation of the
peritoneum.
○ One form of peritonitis occurs
when the appendix ruptures as
a result of appendicitis.
Appendicitis is an inflammation of the
appendix that is usually caused by a
bacterial infection.
Anatomy and Physiology 27
○
○
The appendix is a small sac
attached to the large intestine
with a layer of visceral
peritoneum.
An infection of the appendix
can rupture its wall, releasing
bacteria into the peritoneal
cavity and causing peritonitis.
The abdominopelvic cavity also has other
specialized membranes in addition to the
parietal and visceral membranes, called
mesenteries.
Mesenteries, which consist of two layers of
peritoneum fused together (figure 1.16c),
connect the visceral peritoneum of some
abdominopelvic organs to the parietal
peritoneum on the body wall or to the visceral
peritoneum of other abdominopelvic organs.
The mesenteries anchor the organs to the
body wall and provide a pathway for nerves
and blood vessels to reach the organs. Other
abdominopelvic organs are more closely
attached to the body wall and do not have
mesenteries. Parietal peritoneum covers these
other organs, which are said to be
retroperitoneal
(retro,
behind).
The
retroperitoneal organs include the kidneys,
the adrenal glands, a portion of the pancreas,
parts of the intestines, and the urinary bladder
(figure 1.16c).
Figure 1.16 Location of Serous Membranes
(a) Frontal section showing the parietal
pericardium (blue), visceral pericardium
(red), and pericardial cavity.
(b) Frontal section showing the parietal
pleura (blue), visceral pleura (red), and
pleural cavities.
(c)
Sagittal
section
through
the
abdominopelvic cavity showing the
parietal peritoneum (blue), visceral
peritoneum (red), peritoneal cavity,
mesenteries
(purple),
and
retroperitoneal organs.
(d) Photo of mesentery (green) in a cadaver.
Anatomy and Physiology 28
Assess Your Progress
26. What structure separates the thoracic
cavity from the abdominal cavity? The
abdominal cavity from the pelvic cavity?
27. What structure divides the thoracic cavity
into right and left parts?
28. What is a serous membrane and its
function? Differentiate between the parietal
and visceral portions of a serous membrane.
29. Name the serous membrane–lined cavities
of the trunk.
30. What are mesenteries? Explain their
function.
31. What are retroperitoneal organs? List five
examples
LEARN TO APPLY IT
Renzo, the dancer in the photo, is perfectly
balanced, yet a slight movement in any
direction would cause him to adjust his
position. The human body adjusts its balance
among all its parts through a process called
homeostasis. Let’s imagine that Renzo is
suffering from a blood sugar disorder. Earlier,
just before this photo was taken, he’d eaten an
energy bar. As an energy bar is digested, blood
sugar rises. Normally, tiny collections of cells
embedded in the pancreas respond to the rise
in blood sugar by secreting the chemical
insulin. Insulin increases the movement of
sugar from the blood into the cells. However,
Renzo did not feel satisfied from his energy
bar. He felt dizzy and was still hungry, all
symptoms he worried could be due to a family
history of diabetes. Fortunately, the on-site
trainer tested his blood sugar and noted that it
was much higher than normal. After a visit to
his regular physician, Renzo was outfitted with
an insulin pump and his blood sugar levels are
more consistent. Create an explanation for
Renzo’s blood sugar levels before and after his
visit to the doctor.
Summary
1.1-2 Anatomy and Physiology
1. Anatomy is the study of the body’s
structures.
● Developmental anatomy considers
anatomical changes from conception
to adulthood. Embryology focuses on
the first 8 weeks of development.
● Cytology examines cells, and histology
examines tissues.
● Gross anatomy studies organs from
either a systemic or a regional
perspective.
2. Surface anatomy uses superficial structures
to locate internal structures, and anatomical
imaging is a noninvasive technique for
identifying internal (deep) structures.
3. Physiology is the study of the body’s
functions. It can be approached from a cellular
or a systems point of view.
4. Pathology deals with all aspects of disease.
Exercise physiology examines changes caused
by exercise.
1.3 Structural and Functional Organization
of the Human Body
1. Basic chemical characteristics are
responsible for the structure and functions of
life.
2. Cells are the basic structural and functional
units of organisms, such as plants and animals.
Organelles are small structures within cells
that perform specific functions.
3. Tissues are composed of groups of cells of
similar structure and function and the
materials surrounding them. The four primary
tissue types are epithelial, connective, muscle,
and nervous tissues.
4. Organs are structures composed of two or
more tissues that perform specific functions.
5. Organs are arranged into the 11 organ
systems of the human body (see figure 1.3).
6. Organ systems interact to form a whole,
functioning organism.
1.4 Characteristics of Life
Humans share many characteristics with other
organisms, such as organization, metabolism,
responsiveness, growth, development, and
reproduction
1.5 Biomedical Research
Much of our knowledge about humans is
derived from research on other organisms.
1.6 Homeostasis
Homeostasis is the condition in which body
functions, body fluids, and other factors of the
internal environment are maintained at levels
suitable to support life.
Negative Feedback
1. Negative-feedback mechanisms maintain
homeostasis.
2. Many negative-feedback mechanisms
consist of a receptor, a control center, and an
effector.
Anatomy and Physiology 29
Positive Feedback
1. Positive-feedback mechanisms usually
result in deviations further from the set point.
Body Cavities
1. The mediastinum subdivides the thoracic
cavity.
2. Although a few positive-feedback
mechanisms are normal for maintaining
homeostasis
in
the
body,
some
positive-feedback mechanisms can be harmful.
2. The diaphragm separates the thoracic and
abdominal cavities.
3. Normal postive-feedback mechanisms
include blood clotting and childbirth labor.
Harmful positive-feedback examples include
decreased blood flow to the heart.
Serous Membranes
1. Serous membranes line the trunk cavities.
● The parietal portion of a serous
membrane lines the wall of the cavity,
and the visceral portion is in contact
with the internal organs.
● The serous membranes secrete fluid,
which fills the space between the
visceral and parietal membranes. The
serous membranes protect organs
from friction.
● The pericardial cavity surrounds the
heart, the pleural cavities surround the
lungs, and the peritoneal cavity
surrounds certain abdominal and
pelvic organs.
2. Mesenteries are parts of the peritoneum
that hold the abdominal organs in place and
provide a passageway for blood vessels and
nerves to the organs.
1.7 Terminology and the Body Plan
Body Positions
1. A human standing erect with the face
directed forward, the arms hanging to the
sides, and the palms facing forward is in the
anatomical position.
2. A person lying face upward is supine; a
person lying face downward is prone.
Directional Terms
Directional terms always refer to the
anatomical position, no matter what the actual
position of the body (see table 1.2).
Body Parts and Regions
1. The body can be divided into a central
region, consisting of the head, neck, and trunk,
and the upper limbs and lower limbs.
2. Superficially, the abdomen can be divided
into quadrants or into nine regions. These
divisions are useful for locating internal
organs or describing the location of a pain or a
tumor.
Planes
1. Planes of the body
● A sagittal plane divides the body into
right and left parts. A median plane
divides the body into equal right and
left halves.
● A transverse (horizontal) plane divides
the body into superior and inferior
portions.
● A frontal (coronal) plane divides the
body into anterior and posterior parts.
2. Sections of an organ
● A longitudinal section of an organ
divides it along the length of the organ.
● A transverse (cross) section cuts at a
right angle to the length of the organ.
● An oblique section cuts across the
length of an organ at an angle other
than a right angle.
3. Pelvic bones surround the pelvic cavity.
3. Retroperitoneal organs are located “behind”
the parietal peritoneum.
ANSWER TO LEARN TO APPLY IT
The first Apply It feature in every chapter of
this text is designed to help you develop the
skills to successfully answer critical thinking
questions. The first step in the process is
always to analyze the question itself. In this
case, the question asks you to evaluate the
mechanisms governing Renzo’s blood sugar
levels, and it provides the clue that there’s a
homeostatic mechanism involved. In addition,
the question describes a series of events that
helps create an explanation: Renzo doesn’t feel
satisfied after eating, has elevated blood sugar,
and then is prescribed an insulin pump. In
chapter 1, we learn that homeostasis is the
maintenance of a relatively constant internal
environment. Renzo experienced hunger
despite eating, and his blood sugar levels were
higher than normal. In this situation, we see a
disruption in homeostasis because his blood
sugar stayed too high after eating. Normally,
an increased blood sugar after a meal would
return to the normal range by the activity of
insulin secreted by the pancreas. When blood
sugar returns to normal, insulin secretion
stops. In Renzo’s case, his pancreas has
stopped making insulin. Thus, the doctor
prescribed an insulin pump to take over for his
Anatomy and Physiology 30
pancreas. Now when Renzo eats, the insulin
pump puts insulin into his blood and his blood
sugar levels are maintained near the set point.
Answers to the rest of this chapter’s Apply It
questions are in Appendix G.
Review and Comprehension
1. Physiology
a. deals with the processes or functions
of living things.
b. is the scientific discipline that
investigates the body’s structures.
c. is concerned with organisms and does
not deal with levels of organization,
such as cells and systems.
d. recognizes the static (as opposed to
the dynamic) nature of living things.
e. can be used to study the human body
without considering anatomy.
2. The following are organizational levels for
considering the body.
(1) cell
(2) chemical
(3) organ
(4) organ system
(5) organism
(6) tissue
Choose the correct order for these
organizational levels, from simplest to most
complex.
a. 1,2,3,6,4,5
b. 2,1,6,3,4,5
c. 3,1,6,4,5,2
d. 4,6,1,3,5,2
e. 1,6,5,3,4,2
For questions 3–7, match each organ system
with one of the following functions.
a. regulates other organ systems
b. removes waste products from the
blood; maintains water balance
c. regulates temperature; reduces water
loss; provides protection
d. removes foreign substances from the
blood; combats disease; maintains
tissue fluid balance
e. produces
movement;
maintains
posture; produces body heat
7. Urinary system
8. The characteristic of life that is defined as
“all the chemical reactions taking place in an
organism” is
a. development.
b. growth.
c. metabolism.
d. d. organization.
e. responsiveness.
9. The following events are part of a
negative-feedback mechanism.
(1) Blood pressure increases.
(2) The control center compares actual
blood pressure to the blood pressure set
point.
(3) The heart beats faster.
(4) Receptors detect a decrease in blood
pressure.
Choose the arrangement that lists the events
in the order they occur.
a. 1,2,3,4
b. b. 1,3,2,4
c. 3,1,4,2
d. 4,2,3,1
e. 4,3,2,1
10. Which of these statements concerning
positive feedback is correct?
a. Positive-feedback responses maintain
homeostasis.
b. Positive-feedback responses occur
continuously in healthy individuals.
c. Birth is an example of a normally
occurring
positive-feedback
mechanism
d. When cardiac muscle receives an
inadequate
supply
of
blood,
positive-feedback
mechanisms
increase blood flow to the heart.
e. Medical therapy seeks to overcome
illness by aiding positivefeedback
mechanisms.
11. A term that means nearer the attached end
of a limb is
a. Distal.
b. lateral.
c. medial
d. proximal.
e. superficial.
3. Endocrine system
4. Integumentary system
5. Muscular system
6. Nervous system
12. Which of these directional terms are
paired most appropriately as opposites?
a. superficial and deep
b. medial and proximal
c. distal and lateral
d. superior and posterior
e. anterior and inferior
Anatomy and Physiology 31
13. The part of the upper limb between the
elbow and the wrist is called the
a. arm.
b. forearm.
c. hand
d. inferior arm.
e. lower arm.
14. A patient with appendicitis usually has
pain in the quadrant of the abdomen.
a. left-lower
b. right-lower
c. left-upper
d. right-upper
15. A plane that divides the body into anterior
and posterior parts is a
a. frontal (coronal) plane.
b. sagittal plane.
c. transverse plane.
16. The lungs are
a. part of the mediastinum.
b. surrounded by the pericardial cavity.
c. found within the thoracic cavity.
d. separated from each other by the
diaphragm.
e. surrounded by mucous membranes.
17. Given the following organ and cavity
combinations:
(1) heart and pericardial cavity
(2) lungs and pleural cavity
(3) stomach and peritoneal cavity
(4) kidney and peritoneal cavity
Which of the organs is correctly paired with a
space that surrounds that organ?
a. 1,2
b. 1,2,3
c. 1,2,4
d. 2,3,4
e. 1,2,3,4
18. Which of the following membrane
combinations are found on the superior and
inferior surface of the diaphragm?
a. parietal pleura—parietal peritoneum
b. parietal pleura—visceral peritoneum
c. visceral pleura—parietal peritoneum
d. visceral pleura—visceral peritoneum
19. Which of the following organs are not
retroperitoneal?
a. adrenal glands
b. urinary bladder
c. kidneys
d. Pancreas
e. stomach
20. The liver, spleen, and gallbladder are found
in which body cavity?
A. Abdominal cavity
B. Dorsal cavity
C. Pelvic cavity
21. Which of the following is NOT found in
the thoracic cavity?
A. Heart
B. Lungs
C. Brain
23. A scientist studying body cavities and
sizes of different organisms concludes
that large organisms need body cavities
to facilitate their movement. Which of
the following statements supports that
idea?
A. The smallest organisms have body cavities,
while some of the largest do not.
B. As organisms increase in size and
complexity, they tend to have more body
cavities.
C. All organisms have body cavities, and the
fastest ones have the fewest.
24. What is the name of the fluid that protects
the brain and spinal cord?
a. Meningeal
b. Cerebrospinal
c. Lumbar
d. cranial
25. How many types of serous membrane are
there?
A. 1
B. 2
C. 3
D. 4
26. Which is the largest serous membrane?
A. Pericardium
B. Pleura
C. Peritoneum
D. Tunica vaginalis
27. What is an important function of the
pericardium?
A. Transport oxygen to the lungs
B. Allow movement of the heart
C. Protect the kidneys
D. Remove toxins
Comprehensive Question
1. What is a body cavity?
2. Compare and contrast ventral and
dorsal body cavities.
3. Identify the subdivisions of the ventral
cavity and the organs each contains.
4. Describe the subdivisions of the dorsal
cavity and its contents.
Anatomy and Physiology 32
5. Identify and describe all the tissues
that protect the brain and spinal cord.
6. What do you think might happen if
fluid were to build up excessively in
one of the body cavities?
7. Explain why a woman’s body can
accommodate a full-term fetus during
pregnancy, without damage to her
internal organs.
8. Which body cavity does the needle
enter in a lumbar puncture?
9. What are the names given to the three
body cavity divisions where the heart
is located?
10. What are the names given to the three
body cavity divisions where the
kidneys are located?
11. True or False. The stomach is located
in the dorsal cavity.
12. True or False. A body cavity must open
to the outside world.
13. True or False. The vertebral column
surrounds the spinal cavity.
14. The _________ cavity is directly below
the thoracic cavity.
Critical Thinking
1. Exposure to a hot environment causes the
body to sweat. The hotter the environment,
the greater the sweating. Two anatomy and
physiology students are arguing about the
mechanisms involved. Student A claims that
they are positive feedback, and student B
claims they are negative feedback. Do you
agree with student A or student B, and why?
2. A male has lost blood as a result of a
gunshot wound. Even though the bleeding has
been stopped, his blood pressure is low and
dropping, and his heart rate is elevated.
Following a blood transfusion, his blood
pressure increases and his heart rate
decreases.
Which
of
the
following
statement(s) is (are) consistent with these
observations?
a. Negative-feedback mechanisms can be
inadequate without medical intervention.
b.
The
transfusion
interrupted
a
positive-feedback mechanism.
c. The increased heart rate after the gunshot
wound and before the transfusion is a result of
a positive-feedback mechanism.
d. a and b e. a, b, and c
3. Provide the correct directional term for the
following statement: When a boy is standing
on his head, his nose is to his mouth.
4. During pregnancy, which of the mother’s
body cavities increases most in size?
5. A woman falls while skiing and is
accidentally impaled by her ski pole. The pole
passes through the abdominal body wall and
into and through the stomach, pierces the
diaphragm, and finally stops in the left lung.
List, in order, the serous membranes the pole
pierces.
Answers in appendix F
Answer
Multiple Choice
1. A. Physiology
Deals with the processes or functions of living
things.
2. B. 2,1,6,3,4,5
Correct order for the organizational levels,
from simplest to most complex.
(1) chemical
(2) cell
(3) tissue -organ
(4) organ
(5) organ system
(6) organism
3. D. Endocrine system
Removes foreign substances from the blood;
combats disease; maintains tissue fluid
balance
4. C. Integumentary system
Regulates temperature; reduces water loss;
provides protection
5. E. Muscular system
Produces movement;
produces body heat
maintains
posture;
6. A. Nervous system
Regulates other organ systems
7. B. Urinary System
Removes waste products from the blood;
maintains water balance
8. C. Metabolism
Metabolism is the body's process of balancing
the system. It involves two kinds of activities
that occur at the same time. These activities
are called anabolism and catabolism.
9. D. 4,2,3,1
(1) Receptors detect a decrease in blood
pressure
(2) The control center compares actual blood
pressure to the blood pressure set point.
(3) The heart beats faster.
(4) Blood pressure increases
Anatomy and Physiology 33
10. C. Birth is an example of a normally
occurring positive-feedback mechanism.
11. D. Proximal.
12. A. Superficial and Deep
13. B. Forearm
14. B. right-lower
15. A. frontal (coronal) plane.
16. C. found within the thoracic cavity.
17. B. 1,2,3
(1) heart and pericardial cavity
(2) lungs and pleural cavity
(3) stomach and peritoneal cavity
18.
A.
peritoneum
parietal
pleura—parietal
19. E. Stomach
20. A. Abdominal cavity
These organs, along with the majority of the
organs in the body, reside within the
abdominal cavity. The pelvic cavity houses
mainly the reproductive organs and the
bladder, while the dorsal cavity houses the
brain and spinal cord.
21. C. Brain
The brain is housed in the dorsal cavity. The
ventral body cavity, which contains the
thoracic cavity, contains most of the body’s
organs. The thoracic cavity is further divided
into left and right pleural cavities which hold
the lungs, and the mediastinum, which houses
the heart within its own pericardial cavity.
23. B. As organisms increase in size and
complexity, they tend to have more body
cavities.
This is true. Flatworms have no layers, while
the more complex segmented worms have full
coeloms. As such, the segmented worms can
grow much larger. While the theory is not fully
fleshed out, it is clear that larger organisms
tend to have more body cavities. This could be
to support their complex movements, or it
could just be a byproduct of the development
of a third germ layer.
25. b. Cerebrospinal
Cerebrospinal fluid acts like a cushion that
helps protect your brain and spinal cord from
sudden impact or injury. The fluid also
removes waste products from the brain and
helps your central nervous system work
properly.
26. D. 4
There are four types of serous membranes: the
pericardium that surrounds the heart, the
pleura that surround the lungs, the
peritoneum that surrounds the abdominal
cavity and associated organs, and the tunica
vaginalis that surrounds the testes.
27. C. Peritoneum
The peritoneum is the largest of the serous
membranes. The peritoneum is very
convoluted in some regions, folding in upon
itself and increasing the surface area. The
unfolded surface area of the peritoneum is
close to that of the surface area of the skin.
28. B. Allow movement of the heart
The pericardium is the serous membrane
that surrounds the heart. It has several
protective functions including allowing
movement of the heart within the body cavity
without friction, protecting the heart from
external stimuli by controlling inflammation
and immune responses, and the synthesis
and release of a number of molecules
including cytokines and antigens.
Critical Thinking
1. Student B is correct.
Body temperature begins to rise as a result of
exposure to the hot environment. Sweating
eliminates heat from the body and lowers
body
temperature.
Body
temperature
returning to its ideal normal value is an
example of negative feedback. Student A
probably thought it was positive feedback
because sweating continued to increase.
However, sweating is the response. The
variable being regulated by sweating is body
temperature.
2. Answer e is correct.
Positive-feedback mechanisms continuously
stimulate a response until the initial stimulus
is removed. They are sometimes harmful. The
continually decreasing blood pressure is an
example of a harmful positive feedback
mechanism. Negative-feedback mechanisms
result in a return to homeostasis. The elevated
heart rate is a negative-feedback mechanism
that attempts to return blood pressure to a
normal
value.
In
this
case,
the
Anatomy and Physiology 34
negative-feedback mechanism is inadequate to
restore homeostasis, and medical intervention
(a transfusion) is necessary.
3. When a boy is standing on his head, his
nose is superior to his mouth. Directional
terms refer to a person’s body in the
anatomical position, not to the body’s current
position.
4. The uterus is located in the pelvic cavity.
The pelvic cavity, however, is surrounded by
the bones of the pelvis and does not increase
in size during pregnancy. Instead, as the fetus
grows, the expanding uterus must move into
the abdominal cavity, thereby crowding the
abdominal organs and dramatically increasing
the size of the abdominal cavity.
5. After the pole passes through the
abdominal wall, it pierces the parietal
peritoneum. In passing through the stomach,
it penetrates the visceral peritoneum, the
stomach itself, and the visceral peritoneum on
the other side of the stomach. Because the
diaphragm is lined inferiorly by parietal
peritoneum and superiorly by parietal pleura,
these are the next two membranes pierced.
The pole then passes through the pleural
space and visceral pleura to enter the lung.
Anatomy and Physiology 35