Chapter 1 – Introduction to anatomy and
physiology
A new language
Anatomical Position

Body erect

feet slightly apart

palms facing forward

thumbs point away from
body
The new language – anatomical position

The anatomical position is
extremely
important
in
studying anatomy since it is
universal.

This allows professionals to
easily communicate with each
other, even if they are from
different
countries
or
backgrounds

Regardless of the patient body
position – you ALWAYS
refer to anatomical position
Other concepts you need to know if you want to speak
the language
(you’ll do most of it in the lab)

Body planes

Dorsal and ventral cavities

Abdominopelvic quadrants and 9 regions

Organ systems

Membranes
Overview of Anatomy and Physiology

Anatomy – the study of the structure of body parts and their
relationships to one another


Gross or macroscopic – large visible body structures (heart,
lungs, kidney etc.)
Different ways to approach gross anatomy:




Regional – study of all the structure in a particular region of the
body (leg, abdomen etc.)
Systemic – study a particular system at a time.
Microscopic – deals with structures that are too small to be seen
with the naked eye

Cytology – relates to the cells

Histology – study of the tissues
Physiology – the study of the function of the body
Specialized Branches of Anatomy



Pathological anatomy – study of structural
changes caused by disease
Radiographic anatomy – study of internal
structures visualized by specialized scanning
procedures such as X-ray, MRI, and CT scans
Molecular biology – study
structures at a subcellular level
of
anatomical
Keep in mind.........

Anatomy explains physiology

Form and function are interrelated
The function and process


Those are 2 related topics of physiology
The function of a physiological system is the “why” of a
system event


Why does the system exist and why does the event
happen?

Why red blood cells transport oxygen?

They do so because the cells need oxygen to
survive
The process is “how”

How do the RBC transport the oxygen?

The oxygen binds to hemoglobin
The levels of organization in the body, with the
four primary tissue types
EXTRACELLULAR
MATERIAL
AND FLUIDS
combine
to form
CELLS
TISSUES
EPITHELIAL TISSUE
CONNECTIVE TISSUE
combine
to form
MUSCLE TISSUE
ORGANS
NEURAL TISSUE
interact
in
ORGAN SYSTEMS
2401
2402
Necessary Life Functions

Maintaining boundaries – the internal environment
remains distinct from the external environment


Cellular level
membranes
–
accomplished
by
plasma
Organismal level – accomplished by the skin
Survival Needs

Nutrients – needed for energy and cell building

Oxygen – necessary for metabolic reactions



Water – provides the necessary environment for
chemical reactions (60-8% of body weight)
Normal body temperature – necessary for chemical
reactions to occur at life-sustaining rates (why is it
important to maintain core body temperature?)
Atmospheric pressure – required for proper
breathing and gas exchange in the lungs
Some environments in our body – fluid compartments

Fluids in the body are compose of water and solutes

There are 2 distinct fluid compartments


Intracellular fluid (ICF)

The cytosol of cells

Makes up about two-thirds of the total body water
Extracellular fluid (ECF)

Major components include the plasma and lymph

Minor components include all other extracellular
fluids (water in dense CT, bone, fluid between
visceral and parietal membranes.)
Cations and Anions in Body Fluids
Homeostasis


Homeo – unchanging + stasis – standing
The ability to maintain a relatively stable internal
environment in an ever-changing outside world


The internal environment of the body is in a
dynamic state of equilibrium – it is not a precise
value
Homeostatic regulation is the adjustment
physiological systems to preserve homeostasis

of
It happens in an environment that is inconsistent,
unpredictable and at times – dangerous
Important components of homeostasis in the ECF*
Normal range
Approximate
short-term
nonlethal limit
Oxygen
35-40
10-1000
mmHg
Carbon dioxide
35-45
5-80
mmHg
Sodium ions
138-146
115-175
mmol/L
Potassium ions
3.8-5.0
1.5-9.0
mmol/L
Calcium ions
1.0-1.4
0.5-2.0
mmol/L
Chloride ions
103-112
70-130
mmol/L
Bicarbonate ions
24-32
8-45
mmol/L
Glucose
75-95
20-1500
Mg/dl
98-98.8 (37.0)
65-110 (18.343.3)
0F (0C)
7.3-7.5
6.9-8.0
Body temperature
Acid-base
Medical Physiology – Guyton and Hall, 11th ed.
units
pH
Maintaining homeostasis involves cooperation between systems
Homeostatic imbalances

If the body fails to maintain homeostasis it may result in a
disease or pathological condition

Diseases divide into 2 groups according to their origin:

Internal failure of normal physiological process


Abnormal cell growth, Production of antibodies
against the body’s own tissues, Premature cell
death, Inherited disorders
External sources

Toxic chemicals, Trauma, Foreign invaders
Local and long-distance control pathways


Local / autoregulation/ intrinsic control – in the cell or
tissue – autocrine or paracrine mechanisms (CO2 levels in
the tissue influence diameter of local capillaries)
Long distance control/extrinsic involves the nervous and
endocrine systems.

The long distance neural control involves 3
components – sensor, integration center and effector

The endocrine cells receive the stimulus directly and
respond by releasing hormones (will be discussed in
APII).
Homeostatic control

Some aspects of control systems:

Tonic control – maintaining “moderate activity” –
example – blood vessel diameter. Tonic control is not
stopping or starting activity (similar to turning radio
volume louder or softer)

Antagonistic control – for systems that are not under
tonic control either by hormones or the nervous system
(insulin and glucagon, sympathetic and parasympathetic)
Tonic control
Homeostatic Control Mechanisms components

The three components of control mechanisms:




Sensory receptor (NOT a membrane receptor) –
monitors the environments and responds to
changes (stimuli)
Control center – determines the set point at which
the variable is maintained
Effector – provides the means to respond to
stimuli
Pathways – afferent (sensory) and efferent (motor)
Homeostatic Control Mechanisms
3
Input:
Information
sent along
afferent
pathway to
Control
center
Receptor (sensor)
4 Output:
Information sent
along efferent
pathway to
Effector
2 Change
detected
by receptor
5
1
Stimulus:
Produces
change
in variable
Variable (in homeostasis)
Response of
effector feeds
back to
influence
magnitude of
stimulus and
returns variable
to homeostasis
Set
point
Control center
(thermostat)
Signal
wire turns
heater off
Receptor-sensor
(thermometer in
Thermostat)
Heater
off
Effector
(heater)
Response;
temperature
drops
Stimulus:
rising room
temperature
Balance
Response;
temperature
rises
Stimulus:
dropping room
temperature
Heater
on
Set
point
Effector
(heater)
Receptor-sensor
(thermometer in
Thermostat)
Signal
wire turns
heater on
Control center
(thermostat)
Figure 1.5
Positive Feedback

In positive feedback systems, the output enhances or
exaggerates the original stimulus

Body is moved away from homeostasis


Normal range is lost

Used to speed up processes
Positive feedback is also known as a “vicious cycle” – if
not stopped can lead to death
Figure 1.6
Positive feedback is NOT homeostatic process