Lecture Human anatomy and physiology - Chapter 1: The human body: An orientation (part a)

Chapter 1

The Human Body: 
An Orientation: 
Part A


Overview of Anatomy and
Physiology
Anatomy: The study of structure of the

body
Subdivisions:
Gross or macroscopic (e.g., regional,
surface, and systemic anatomy)
Microscopic (e.g., cytology and
histology)
Developmental (e.g., embryology)


Overview of Anatomy and
Physiology
Essential tools for the study 

of anatomy:
Anatomical terminology
Observation
Palpation
Auscultation

Overview of Anatomy and
Physiology
Physiology: The study of

function of the body at many
levels
Subdivisions are based on
organ systems (e.g., renal,
digestive, cardiovascular
physiology)


Overview of Anatomy and
Physiology
Essential tools for the study of

physiology:
Ability to focus at many levels
(from systemic to cellular and
molecular)
Basic physical principles (e.g.,
electrical currents, pressure, and
movement)


Principle of Complementarity

Anatomy and physiology are

inseparable.

Function always reflects
structure
What a structure can do
depends on its specific form


Levels of Structural
Organization
Chemical: atoms and molecules (Chapter

2)
Cellular: cells and their organelles
(Chapter 3)
Tissue: groups of similar cells (Chapter 4)
Organ: contains two or more types of
tissues
Organ system: organs that work closely
together
Organismal: all organ systems


Atoms

Molecule

1 Chemical level
Atoms combine to form molecules.
Cardiovascular
system
Heart

Blood
vessels

Organelle
Smooth muscle cell

2 Cellular level
Cells are made up of
molecules.

Smooth muscle tissue

3 Tissue level
Tissues consist of similar
types of cells.
Blood vessel (organ)
Smooth muscle tissue
Connective tissue

Epithelial
tissue
4 Organ level
Organs are made up of different types
of tissues.
6 Organismal level
5 Organ system level
The human organism is made up Organ systems consist of different
of many organ systems.
organs that work together closely.
Figure 1.1, step 6

Overview of Organ Systems

 Major organs and functions

of the 11 organ systems


Digestive system
Nervous system
Respiratory system
Cardiovascular system
Lymphatic system
Urinary system
Muscular system
Skeletal system
Integumentary system
Endocrine system
Reproductive system

Organ Systems


Organ Systems
Interrelationships
All cells depend on organ

systems to meet their survival
needs

Organ systems work
cooperatively to perform
necessary life functions


Necessary Life Functions
1. Boundary: Maintaining boundaries

between internal and external
environments
 Plasma membranes
 Skin
1. Movement: (contractility)
 Of body parts (skeletal muscle)
 Of substances (cardiac and smooth
muscle)


Necessary Life Functions
3. Responsiveness: The ability to

sense and respond to stimuli
 Withdrawal reflex
 Control of breathing rate
4. Digestion:
 Breakdown of ingested
foodstuffs
 Absorption of simple molecules

Necessary Life Functions
5. Metabolism: All chemical

reactions that occur in body
cells
 Catabolism and anabolism
6. Excretion: The removal of
wastes from metabolism and
digestion



Necessary Life Functions
7. Reproduction: 
 Cellular division for growth

or repair
 Production of offspring
8. Growth: Increase in size of a
body part or of organism


Survival Needs
1. Nutrients:
 Chemicals for energy and cell

building
 Carbohydrates, fats, proteins,
minerals, vitamins
2. Oxygen:

 Essential for energy release
(ATP production)


Survival Needs
3. Water:
 Most abundant chemical in the
body
 Site of chemical reactions
4.  Body temperature:
 Affects rate of chemical
reactions
5. Atmospheric pressure:
 For adequate breathing and gas


Homeostasis
It is the maintenance of a relatively 

stable internal environment despite 
continuous changes both inside and 
out

A dynamic state of equilibrium


Homeostatic Control Mechanisms
Involve continuous monitoring

and regulation of many factors

(variables)
Nervous and endocrine 
systems accomplish the
communication via nerve
impulses and hormones


Components of a Control
Mechanism
1. Receptor (sensor)
 Monitors the environment
 Responds to stimuli (changes in

controlled variables)
2. Control center
 Determines the set point at which
the variable is maintained
 Receives input from receptor
 Determines appropriate response


Components of a Control
Mechanism
3. Effector
 Receives output from control

center
 Provides the means to
respond
 Response acts to reduce or

enhance the stimulus


Input: Information
Control
sent along afferent
Center
pathway to control
center.
Afferent
Efferent
pathway
pathway
2
Receptor
Receptor
detects
change.
IMB
A LA
1
NC
E
Stimulus
produces
BALANCE
change in
variable.
3

4 Output:

Information sent along
efferent pathway to
effector.
Effector

IMB
A LA
NC
E

5

Response
of effector
feeds back
to reduce
the effect of
stimulus
and returns
variable to
homeostatic
level.

Figure 1.4, step 5


Negative Feedback
The response reduces or shuts off the

original stimulus
Examples:
Regulation of body temperature (a
nervous mechanism)
Regulation of blood volume by ADH
(an endocrine mechanism)


Control Center
(thermoregulatory
center in brain)

Information sent
along the afferent
pathway to control
center

Afferent
pathway

Information sent
along the efferent
pathway to
effectors

Efferent
pathway

Receptors

Temperature-sensitive
cells in skin and brain

Effectors
Sweat glands
Sweat glands activated
Response
Evaporation of sweat
Body temperature falls;
stimulus ends

Stimulus
Body temperature
rises

BALANCE

Stimulus

Response
Body temperature rises;
stimulus ends

Body temperature falls

Receptors
Temperature-sensitive
cells in skin and brain

Effectors

Skeletal muscles

Shivering
begins

Information sent
along the efferent
pathway to effectors

Efferent
pathway

Afferent
pathway

Control Center
(thermoregulatory
center in brain)

Information sent
along the afferent
pathway to control
center

Figure 1.5


Negative Feedback: Regulation
of Blood Volume by ADH
Receptors sense decreased blood

volume
Control center in hypothalamus
stimulates pituitary gland to release
antidiuretic hormone (ADH)
ADH causes the kidneys
(effectors) to return more water to
the blood