P.1
Lecture Notes: Unit I: Organization of the Human
Chapter One - An Introduction to the Human Body
1.
II.
III.
Anatomy and Physiology defined and interrelated one to the other
A. Ana = "apart" + tomy (from tome) = "to cut" Literally: "to cut apart", but popularly:
the study of structures, their arrangement and their relationships
Topics of Anatomy: Microscopic Anatomy (Cytology, Histology),Gross Anatomy (Surface
Anatomy, Regional Anatomy, Systemic Anatomy), Developmental Anatomy (Embryology),
Radiographic Anatomy, Pathological Anatomy, etc. (See Table 1.1 for specific selection of
subdiscipline names and explanations.)
B. Physi = "work" or "nature" + -ology = "the study of” Literally: "the study of work,
but popularly: the science of body functions; that is, how the structures of the body work. Topics
of Physiology: Cell Physiology, Neurophysiology, Renal Physiology, Cardiac Physiology, other
Organ System Physiology, Exercise Physiology, etc. (Again, See Table 1.1)
C. Three non-invasive techniques associated with the clinical application of Anatomy and Physiology are palpation, auscultation, and percussion.
D. Complementarity of Anatomy (Structure) and Physiology (Functioning): "Structure determines function." Although Anatomy and Physiology may be studied in isolation one from the
other, they are truly inseparable sciences because function always reflects structure. That is,
what a structure can do depends on its specific form. Structure determines function. This is called
the principle of complementarity of structure and function. This course will consistently stress
this principle to help you understand the meaning of what you are learning. For any given structure, a description of its anatomy is accompanied by an explanation of its function; always emphasizing that structural characteristics contribute to and define that function.
Levels of Body Organization
A. There are six levels of structural hierarchy: .
1. Chemical Level - interaction of atoms and subatomic particles
a. Atoms (Matter is composed of Elements; smallest whole units of elements are
atoms. )
b. Molecules (Two or more atoms held together by one or more bonds)
2. Cellular Level- smallest structural/functional living units of the body; specific sub-cellular
structures called organelles make specialized contributions to the cell
3. Tissue Level- aggregates of cells (and any materials surrounding them) that work together
to perform a particular function.
4. Organ Level- two or more tissue-types that associate with one another in a recog
nizable way to perform specific functions.
5. Organ-System Level (System Level) - several related organs that have one or more
common function(s).
6. Organism Level - a living individual composed of multiple organ-systems.
(See Table 1.2 to reference the Eleven Systems of the human organism: Integumentary,
Skeletal, Muscular, Nervous, Endocrine, Cardiovascular, Lymphatic/Immune, Respiratory, Digestive, Urinary, Reproductive.
Characteristics of the Living Human Organism (Basic Life Processes)
A. Living organisms may be distinguished from non-living entities by six processes:
1. Metabolism - sum total of all chemical reactions in the body (includes anabolism: "build
up" or synthesis rxns. as well as catabolism: "tear-down" or decomposition rxns.
P.2
IV.
Most reactions are a combination of anabolic and catabolic reactions
taking place sequentially; many reactions are exchange reactions.)
2. Responsiveness - detection of changes in the internal/external environment with the
ability to react to those changes.
3. Movement - of the organism, of its cells, or of fluids/substances over body surfaces.
4. Growth - increase in body size resulting from an increase in cellular size and/or
cell numbers.
5. Differentiation - the process of cells becoming specialized ftom their non-special
ized ancestors in order to perform some new, distinct task (The undifferentiated,
non-specialized ancestor cells are referred to as stem cells.)
6. Reproduction - formation of new cells for growth, repair, or replacement; or the
production of a new individual.
(Although not all of these processes are occurring in all cells throughout the body all the
time, when they cease to occur properly, the result is death of the cells and ultimately
death of the human organism.)
Homeostasis - Homeo = "sameness" + Stasis = "to stay" or "to stand" Literally: the condition of
the body's internal environment remaining more or less constant (the same). More appropriately:
Homeostasis describes the dynamic equilibrium of the body's internal environment by which it
remains stable; that is, within relatively constant (and narrow) limits despite many changes in the
external environment.
Considerations when dealing with Homeostasis:
A. Homeostasis is a central theme of human anatomy and physiology since it represents the balance
of normal, healthy body activities in order to maintain controllable conditions within their very
narrow range of ideal values.
B. Homeostasis is regulated by feedback systems:
1. Three components of a feedback system:
a. Receptor - monitors changes in a condition and sends impulses to a control center
(creates the “input”, usually in the form of a nerve impulse or chemical signal.)
b. Control center - receives information from the receptor, sets range of values for
that condition, determines output. (Usually spinal cord, brain, or endocrine organ)
c. Effector - body structure which receives output from the control center and produces a response.
2. Two types of feedback systems
a. Negative feedback system: "The output reverses the input".
1. The result is to REVERSE the original change to the controlled condition;
ie: If original input was a decrease in activity, then output will be to increase
it. Conversely, if original input was an increase in activity, then output will
be to decrease it. Another way of stating it is that there is an.
opposite directional change with a negative feedback systems.
2. The result of a negative feedback system should be to maintain the controlled condition within its very narrow, ideal range.
3. Examples: body temperature, blood pH, blood glucose levels, most hormone
levels. Most feedback systems in the body are of this type.
b. Positive feedback system: "The output reinforces the input".
1. The result is to strengthen/reinforce the original change to the controlled
condition. Since the original input is an increase in activity, then the out-
P. 3
V.
put will be to increase that activity even further. Another way of stating it is
that there is a same directional change with a positive feedback system.
2. The result of a positive feedback system is to make the controlled condition progressively increase.
3. Examples: increasing levels of oxytocin during childbirth; blood-clotting
mechanism; estrogen production during the pre-ovulatory portion of the
ovarian cycle.
3. Homeostatic imbalance: Disorders (disease) arise with the loss of homeostasis.
a. Medical professional attempt to return a patient to homeostasis.
b. Epidemiology is the study of the causes of a disease.
c. Pharmacology is the study of therapeutic drugs used in treatments of diseases.
Anatomical Terminology
A. All terminology is related to anatomical position, referring to a specific stance for examination of
the body. When in anatomical position, the body has face and toes forward, upper extremities are
comfortably at the sides, and palms are facing forward. In this position, the body now has just two
surfaces: anterior (aka ventral) and posterior (aka dorsal).
1. Prone refers to the body (or a part of the body) lying face down.
2. Supine refers to the body (or a part of the body) lying face up.
B. Planes and (resulting) Sections of the body
1. Sagittal plane separates the body into right and left portions
a. Midsagittal plane (Median plane) separates the body/body part into equal right/left portions
b. Parasagittal plane separates the body into unequal right/left portions.
2. Coronal plane separates the body/body-part into anterior and posterior portions.
3. Transverse plane divides the body/body-part into superior and inferior portions.
4. Oblique plane passes through the body/body-part at an angle.
C. Directional terms (and their synonyms where applicable)
1. superior refers to a structure which is toward the head (aka cephalad)
2. inferior refers to a structure which is toward the lower part of the body (aka caudad)
3. anterior - nearer to. or at the front of the body/body-part (aka ventral)
4. posterior - nearer to or at the back of the body/body-part (aka dorsal)
5. medial- nearer to the midline of the body/body-part
6. lateral- farther away from the midline of the body/body-part
7. intermediate -located between two structures
8. ipsilateral - on the same side as another structure
9. contralateral - on the opposite side of the body from another structure
10. proximal - nearer to the origin of a structure or to the attachment of a limb to the trunk
11. distal – farther from the origin of a structure or from the attachment of a limb to the trunk
12. superficial- toward or on the surface of the body/body-part
13. deep - away from the surface of the body/body-part
14. parietal - pertaining to the outer wall of a body cavity
15. visceral - pertaining to the organs or to the covering of organs contained in body cavities
D. Body cavities- there are two cavities which carry the name "body cavity":
1. The Dorsal Body Cavity
a. One continuous cavity with no physical partitions in it, but separated into two sub-sections:
1. Cranial cavity - contains the brain
2. Vertebral (spinal) cavity - contains the spinal cord
P.4
b. Lined by three connective tissue layers collectively called the meninges.
(These are the dura mater, arachnoid mater, and pia mater from superficial to deep.)
2. The Ventral Body Cavity
a. This cavity has a physical partition, the diaphragm, separating it into two sub-sections;
and each of these two sub-sections is divided into two portions:
1. Thoracic cavity - lying superior to the diaphragm
(a) Pericardial cavity - contains the heart. The heart is covered by the visceral
pericardium and the cavity is lined by parietal pericardium.
(b) Pleural cavities - there are two of these; each one containing a lung. Each lung
is covered by visceral pleura and each pleural cavity is lined
by parietal pleura.
( c) Mediastinum - this is NOT a cavity; but rather a region, or dividing structure, in
the midline of the thoracic cavity which contains the esophagus,
trachea, thymus gland, large blood vessels, nerves, and surrounds
the pericardial cavity.
b. Abdominopelvic cavity - lying inferior to the diaphragm (Note: the diaphragm is NOT in
either the thoracic nor abdominopelvic cavity - it just separates the two.)
(a) Abdominal cavity - contains the stomach, spleen, liver, gallbladder, small and large
intestines, all of which are covered by visceral peritoneum and
the cavity is lined by parietal peritoneum.
(b) Pelvic cavity - contains the urinary bladder, reproductive organs, and a portion of
of the large intestine. These are covered by the visceral peritoneum
and the cavity is lined by parietal peritoneum.
Note: All membranes of the Ventral Body Cavity: the pericardium, the pleura, and the peritoneum are serous
membranes. That is, they secrete a viscous, lubricant called serous fluid, which is found between the
parietal and visceral reflections of each of these membranes. This serous fluid is what is in the pericardial cavity, the pleural cavities, and the peritoneum (abdominopelvic cavity.) It is what allows for
the frictionless movement of all our viscera over the associated body wall and over each other. When
this fluid is NOT secreted nornally, it causes the organ surfaces to "rub" very painfully - as in
pericarditis, peritonitis, or pleurisy.
E. Abdominopelvic regions and quadrants
1. Abdominopelvic regions are used by anatomists to separate the abdominopelvic portions of the torso
into nine regions: (1) R Hypochondriac, (2) Epigastric, (3) L Hypochondriac; (4) R Lumbar,
(5) Umbilical, (6) L Lumbar; (7) R lliac (or R Inguinal), (8) Pubic, (9) L lliac (or L Inguinal). Refer
to Fig. 1.12(a) (These regions result from projecting four imaginary lines in a "tic-tac-toe" type grid: two
vertical lines: from mid-clavicle to the mid-inguinal ligament bilaterally; and two horizontal lines: along the
inferior costal margin and the superior iliac crest.)
2. Quadrants are used by clinicians to indicate locations of body structures for diagnostic and surgical
procedures. Refer to Fig. 1.12(b) (These four quadrants result from projecting just two imaginary
lines: one vertically along the body's midline; and the other horizontally, intersecting the vertical line
as it passes through the umbilicus.) The names of the four quadrants are: (1) Right Upper Quadrant
(RUQ), (2) Left Upper Quadrant (LUQ); (3) Right Lower Quadrant (RLQ), (4) Left Lower
Quadrant (LLQ).