Introduction to Anatomy and Physiology
Introduction to Anatomy and Physiology
Relationship between Anatomy
and Physiology

Anatomy
 The study of internal and external structures of the body
and the physical relationships among body parts

Physiology
 The study of how living organisms perform their vital
functions

Someone studying anatomy might examine how and
where a particular muscle attaches to the skeleton,
whereas someone studying physiology might
consider how a muscle contracts or what forces a
contracting muscle exerts on the skeleton
Relationship between Anatomy
and Physiology
Anatomical info provides clues about
functions (physiology), and physiological
mechanisms can be explained only in
terms of the underlying anatomy
 ALL SPECIFIC FUNCTIONS ARE
PERFORMED BY SPECIFIC
STRUCTURES!!!!!

Relationship between Anatomy
and Physiology
Anatomy can be divided into gross
(macroscopic) anatomy and microscopic
anatomy
 Gross Anatomy

 Examination of relatively large structures
○ Usually visible with unaided eye

5 different forms of gross anatomy
 Surface anatomy
○ Study of general form and superficial markings
 Regional anatomy
○ Anatomical organization of specific areas of body
(head, neck, trunk)
Relationship between Anatomy
and Physiology

5 different forms of gross anatomy (con’t)
 Systemic anatomy
○ Study of the structure of organ systems (skeletal
system, muscular system, cardiovascular system, etc.)
 Developmental anatomy
○ Describes the changes in form that occur between
conception and physical maturity
○ Embryology – study of early developmental processes
 Clinical anatomy
○ Subspecialities important in clinical practice
 Medical anatomy (anatomical features that change during
illness)
 Radiographic anatomy (anatomical structures seen using
imaging techniques)
Relationship between Anatomy
and Physiology

Microscopic Anatomy
 Study of structures that cannot be seen
without magnification

Has 2 major divisions
 Cytology – analysis of the internal structure
of individual cells
 Histology – examination of tissues
Relationship between Anatomy
and Physiology

Physiology
 The study of the function of anatomical
strucures

Can be divided into 4 major specialties
 Cell physiology – study of the function of cells
○ Chemical processes within cells and chemical
interactions between cells
 Special physiology – study of the physiology of
specific organs
 Systemic physiology – study of the functioning
of specific organ systems
 Pathological physiology – study of the effects of
diseases on organ or system fuctions
Introduction to Anatomy and Physiology
Levels of Organization

The Chemical (or Molecular) Level
 Atoms can combine to form molecules with complex
shapes
 The functional properties of a particular molecule are
determined by its unique 3D shape

The Cellular Level
 Molecules interact to form organelles, each of which
has specific functions.
 Organelles are grouped to form cells

The Tissue Level
 Groups of cells working together to perform specific
functions
○ Heart muscle cells interact with other types of cells and
extracellular materials to form cardiac muscle tissue
Levels of Organization

The Organ Level
 Two or more tissues working in combination to
perform several functions
○ Cardiac muscle tissue, in combination with
connective tissue from the bulk of the heart.

The Organ System Level
 Two or more organs interacting
○ The heart and blood vessels work together to form
the cardiovascular system.

The Organism Level
 Highest level of organization
 All organ systems working together
Homeostasis
Homeostasis
One of the roles of the organ systems in
an organism is to maintain homeostasis.
 Homeostasis – maintaining a stable
internal environment.

 Absolutely vital to survival

Homeostatic regulation – adjustment of
physiological systems to preserve
homeostasis.
Homeostasis

2 mechanisms of homeostasis
 Autoregulation (intrinsic regulation) – when a
cell, tissue, organ or organ system adjusts
its activities automatically in response to an
environmental change
○ Ex: when blood oxygen levels decrease in a
tissue, the cells release a chemical that dilate
local blood vessels. This increases blood flow
and, therefore, oxygen.
Homeostasis

2 mechanisms of homeostasis (con’t)
 Extrinsic regulation – from activities of the
nervous and/or endocrine systems.
○ Ex: During exercise, your nervous system
increases heart rate so that blood will circulate
faster. Will also decrease blood flow to less
active organs.
Homeostasis

The nervous system directs rapid, shortterm, and very specific responses
 Response to placing hand on a hot stove

Endocrine system releases hormones
that affect tissues and organs
throughout the body.
 Not immediate, not specific, may be long-
term
Homeostasis

Homeostatic regulatory mechanism
consists of 3 parts
 Receptor – sensor that is sensitive to a
particular change in environment
 Control center – receives and processes info
from receptor and sends out commands
 Effector – cell or organ that responds to the
commands from control center.

Similar to thermostat in your house
Homeostasis

Negative feedback
 Most regulatory mechanisms involve this opposition
to changing conditions
 Example is body temperature control
(thermoregulation)
○ Control center is the hypothalamus region of the brain
○ Hypothalamus receives info from two receptors: skin
receptors and one in hypothalamus
○ Normal body temp is 98.6o. If temp increases, the
control center targets two effectors:
 muscles in the walls of the blood vessels supplying the skin
 sweat glands
Homeostasis

Negative feedback (con’t)
 The muscles in the skin blood vessels relax,
increasing blood flow to skin.
 Sweat glands increase their secretion
 The skin acts like a radiator by losing heat to the
environment
○ Evaporation of sweat speed the process
 As temp returns to normal, temp at
hypothalamus declines, and the control center
becomes less active
 Blood flow and sweat production return to
normal.
Homeostasis

There are variations in normal
homeostatic levels between individuals
 95% of population has body temp between
36.7oC and 37.2oC
 Physicians must keep this in mind when
treating patients.
Homeostasis

Positive feedback
 Produces a response that enhances the change in
the original conditions.
 Usually produces extreme responses
 What if your thermostat was connected to your
heater instead of your air conditioner?
○ What would occur if the temp in your house increased?
 When temp exceeds set point, thermostat would turn on the
heater, and it would continue to run until someone turned off
the thermostat, heater, or intervened in some other way.
 This escalating cycle is called a positive feedback
loop
Homeostasis

Positive feedback (con’t)
 In your body, these loops are found when a
potentially dangerous process must be
completed quickly before homeostasis can be
restored.
○ Ex: immediate danger from a severe cut will
decrease blood pressure and reduce efficiency of
the heart
○ The response is to clot the blood.
○ Each step in the process accelerates the process
until a clot is formed

Labor and delivery of a baby is another
example
Frames of Reference for Anatomical Studies
Frames of Reference for
Anatomical Studies

Early anatomists faced communication
problems.
 A “bump on the back” doesn’t give very
precise info about its location

Prominent anatomical structures serve
as landmarks, distances are measured
in centimeters, and specialized
directional terms are used
Frames of Reference for
Anatomical Studies

Superficial Anatomy
 Anatomical landmarks are used in reference
to the anatomical position
○ Anatomical position – hands at side, palms
facing forward, and feet together
○ ALL descriptions given are in reference to the
anatomical position, unless otherwise noted
 Prone – lying face down in the anatomical
position
 Supine – lying face up in the anatomical
position
Frames of Reference for
Anatomical Studies

Anatomical Regions
 Abdominopelvic quadrants
○ Formed by a pair of lines that intersect at the
umbilicus (naval)
○ Used by physicians to help determine possible
cause of aches, pains, injuries.
○ Internal organs can be found in different
quadrants
 Abdomiopelvic regions
○ More specific than quadrants
○ Preferred by anatomists
Frames of Reference for
Anatomical Studies

Anatomical Directions
 The terms left and light always refer to the
left and right sides of the subject, NOT of the
observer
Frames of Reference for
Anatomical Studies

Sectional Anatomy
 Sometimes the best way to understand
anatomy is to slice through it and look at the
internal organization
 Useful with imaging techniques
 Radiologists use these when looking at films
Frames of Reference for
Anatomical Studies

Planes and Sections
 Transverse plane – right angle to long axis of object,
dividing it into superior and inferior
○ A cut in this plane is called a transverse section
 Frontal plane – parallel to long axis; extends from
side to side, dividing the body into anterior and
posterior
○ A cut in this plane is called a frontal section
 Sagittal plane – parallel to long axis; extends from
front to back, dividing the body in to left and right
○ A cut down the midline is called a midsagittal section
○ Parallel cuts are called parasagittal sections
Frames of Reference for
Anatomical Studies

Body cavities
 Internal chambers where many vital organs can
be found
 2 functions
○ Protect organs
○ Permit change of size and shape of the organs
 Your diaphragm divides your torso into two
cavities
○ Thoracic cavity
○ Abdominopelvic cavity
 Viscera – organs enclosed (fully or partially) by
these cavities
Frames of Reference for
Anatomical Studies

Body cavities (con’t)
 Thoracic cavity
○ Contains lungs and heart, associated organs
of respiratory, cardiovascular, and lymphatic
system; lower esophagus; thymus
○ Boundaries are the ribs and diaphragm
○ Subdivided into left and right pleural cavities,
which each contain a lung.
○ Contains pericardial cavity, which surrounds
the heart
Frames of Reference for
Anatomical Studies

Body cavities (con’t)
 Abdomiopelvic cavity
○ Extends from diaphragm to pelvis
○ Divided into a superior abdominal cavity and
an inferior pelvic cavity
○ The peritoneal cavity surrounds the abdominal
and pelvic cavities
Frames of Reference for
Anatomical Studies

Body cavities (con’t)
 Abdominal cavity contains the liver,
stomach, spleen, small intestine, and most
of the large intestine
○ The kidneys and pancreas lie posteriorly
between the peritoneal cavity and the muscles
of the abdominal cavity
 The pelvic cavity contains distal large
intestine, urinary bladder, and various
reproductive organs