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Introduction to Anatomy
Definitions

Anatomy – Study of body structures and
their relationships to each other.

Always involves question “What is it?”

Physiology – Study of how the body
structures work together to maintain life.

Involves the question “How does it work?”
Levels of Organization
Atoms  Molecules  Cells Tissues
 Organs  Organ Systems 
Organisms
H + C + O  C6H12O6 
Muscle Cells Muscle Tissues 
Heart  Circulatory System  Human
Levels of Structural Organization
Smooth muscle cell
Molecules
2
Atoms
Smooth
muscle
tissue
3 Tissue level
Tissues consist of
similar types of
cells
1 Chemical level
Atoms combine to
form molecules
Heart
Cardiovascular
system
Epithelial
tissue
Smooth
muscle
tissue
Cellular level
Cells are madeConnective
up of molecules
tissue
4 Organ level
Organs are made up of
different types of tissues
Blood
vessels
Blood
vessel
(organ)
6 Organismal level
The human organism is
made up of many organ
systems
5 Organ system level
Organ systems consist of different organs
that work together closely
Figure 1.1
Organ Systems
12 Different Organ Systems
 Each specializes in carrying out a specific
function

Example – Muscular system specializes in
moving
Skeletal system specializes in support
Structure and Function

There is an intimate relationship
between structure and function. One
determines the other.
Explain how the structure of each of
the following determines the
function for which it can be used.
 a. fork
 b. hand
 c. incisors
Functions of Life
Separate internal and external environments
 Move
 Respond to stimuli & communicate
 Digest food
 Carry out chemical reactions in cells
(metabolism)
 Excrete wastes
 Reproduce
 Grow

All functions help to maintain
homeostasis
Homeo = “same”
 Stasis = “same”


Homeostasis – keep a
stable internal
environment even though
things inside and outside
the body are changing
Communication is Essential for
Homeostasis

2 systems control communication:
– Nervous
– Endocrine
Stimulus

The change in the environment

It needs to be reported to the body

Examples – change in temperature,
change in glucose levels, change in water
levels
3 parts of homeostatic control
mechanisms:

Receptor – receives information from the
environment as a stimulus

Control center – analyzes info; decides if
anything needs to be done

Effector – responds to the control center
to make a change if necessary
Example
 Receptor
– Sun (the stimulus)
warms your body. Temperature
receptors in skin send info to brain.
 Control center – Brain sees that
body is getting too warm. Sends
signal to effectors to cool the body.
 Effectors – Sweat glands. Release
sweat to cool body.
Feedback

The effector causes a change.

Results of the change then FEEDBACK to
the control center.
2 Types of Feedback
1. Negative – Most common type in body.
Output from the effector shuts off the
stimulus.
Helps keep things stable.
Works just like the air conditioning system.
Negative system--stimulus causes a
response which reduces the stimulus.
THE HOMEOSTATIC CONTROL
OF BLOOD GLUCOSE LEVELS is
a negative feedback system

2.
Positive feedback– rare in body.
The output of the effector causes more of
the change.
Not useful in homeostasis.
Helps bring about rapid changes.
Examples – in labor
- in blood clotting
Positive feedback: stimulus causes a response
which increases the stimulus. This system pushes
the conditions to an extreme.
Homeostatic Imbalance
Causes disease
 The body cannot tolerate drastic changes
 Occurs naturally as we age – homestatic
systems do not work as well
 Systems can be damaged or injured

Language of Anatomy
Position and Directional Terms
 Regional Terms
 Body Planes and Sections
 Body Cavities and Membranes

Position Terms

Anatomical position – helps describe body
parts.
Resembles standing at attention except
palms face forward and thumbs point
away from body
Directional Terms

Explains where one body structure is in
relation to another.
– Proximal – closer to the midline
– Distal – farther from the midline
– Superior – closer to the head
– Inferior – closer to the feet
– Anterior – closer to the front
– Posterior – closer to the rear
Regional Terms
 Two
main regions:
–Axial: head, neck, and truck
–Appendicular: limbs (arms and
legs)
Body Planes

To study anatomy, body can be cut along
a plane (flat surface).
 Sagittal (“arrow”)
plane divides body
vertically into left and right sections.
 If sagittal plane is on midline =
midsaggital
More planes . . .

Frontal plane – divides body vertically into
anterior (front) and posterior (back).

Transverse plane – a horizontal plane that
divides the body into superior (top) and
inferior (bottom)
Transverse plane through
mid section
Body Cavities
Axial portion of body contains 2 large
cavities:
1. Dorsal body cavity – contains brain
and spinal cord
2.
Ventral body cavity is divided
into 2 subdivisions:
a. thoracic cavity: chest,
contains heart and lungs
b. abdominopelvic cavity: 2
parts
i. Abdomen – most organs
ii. Pelvis – bladder &
reproductive structures
Membranes in Cavities
Ventral body cavity lined with serous
membrane – thin, double layered
 Same membrane covers organs
 Layers of membrane separated by
serous fluid – reduces friction

Medical Imaging
Allows visualization of structures without
surgery
 Useful for confirmation of diagnosis
 Examples of imaging techniques

1-36
Conventional Radiography





A single burst of
xrays
Produces 2-D image
on film
Known as
radiography or xray
Poor resolution of
soft tissues
Major use is
osteology
1-37
Computed Tomography (CT Scan)
Moving x-ray beam
 Image produced on a
video monitor of a
cross-section through
body
 Computer generated
image reveals more
soft tissue detail

– kidney & gallstones

Multiple scans used to
build 3D views
1-38
Ultrasound (US)
High-frequency sound
waves emitted by handheld device
 Safe, noninvasive &
painless
 Image or sonogram is
displayed on video monitor
 Used for fetal ultrasound
and examination of pelvic
& abdominal organs, heart
and blood flow through
1-39
blood vessels

Magnetic Resonance Imaging (MRI)
Body exposed to highenergy magnetic field
 Protons align themselves
relative to magnetic field
 Pulse of radiowaves used
to generate an image on
video monitor
 Can not use on patient
with metal in their body
 Reveals fine detail within
soft tissues

1-40
Positron Emission
Tomography(PET)
Substance that emits
positively charged
particles is injected into
body
 Collision with negatively
charged electrons in
tissues releases gamma
rays
 Camera detects gamma
rays & computer
generates image
displayed on monitor1-41
