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PHYSIOLOGY AND BASIC CONCEPTS OF HOMEOSTASIS |FINDYOURSELF
PHYSIOLOGY
§ It is derived from a Greek word.
o
Physis-------nature
o
Logos-------study
It is the study of biological functions of how
the body works from cell to tissues, tissues to organs, organs to systems, from
systems to organism and how the organism as a whole accomplishes particular
tasks that are essential for life.
•
The
cell is the basic unit of both structure and function in a living being and is
the smallest unit capable of carrying out the processes associated with life.
•
The
tissues are group of cells of similar specialization
•
An
organ is unit made up of several tissue types.
•
A
body system is a collection of related organs.
•
The
body systems are packaged together into a functional whole body(Organism)
•
Organisms
are independent living entities
•
Intracellular
fluid—fluid contained within all of the cells of the body
•
Extracellular
fluid—fluid outside the cells of the body and is the internal environment in
which the cells live. It is composed of plasma and interstitial fluid
Homeostasis
Homeo means “same”
Stasis means to “stand or stay”
Maintenance of a relatively stable internal
environment or body’s coordinated response in order to maintain internal
stability
Factors
homeostatically regulated
1.
Concentration
of nutrient molecules
2.
Concentration
of CO2 and O2
3.
Concentration
of waste products
4.
pH
5.
Concentration
of water , salt and other electrolytes
6.
Temperature
7.
Volume
and pressure
Contribution of body systems to Homeostasis
•
The
Circulatory System
•
The
Digestive System
•
The
Respiratory System
•
The
Urinary System
•
The
Skeletal System
•
The
Muscular System
•
The
Integumentary System
•
The
Immune System
•
The
Nervous System
•
The
Endocrine System
•
Reproductive
system is not essential for homeostasis and therefore not essential for
survival.
Homeostatic
Control System Is a functionally interconnected network of body components that
operate to maintain a given physical or chemical factor in the internal
environment relatively constant around an optimal level.
It Can be classified as:
·
Intrinsic
(local controls) are inherent compensatory
responses of an organ to a change
·
Extrinsic
controls are responses of an organ that are triggered by factors external to the
organ , namely, by the nervous and endocrine systems
·
Both intrinsic and extrinsic control
systems generally operate on the principle of
·
Negative feedback mechanism
In
addition
·
Positive feedback mechanism
·
Feedforward mechanism
Negative feedback mechanism
Change in a
homeostatically control factor triggers
a response that seeks to restore the factor to normal by moving the factor in
the opposite direction of its initial change or it is a pathway where the
response opposes or removes the signal.
Negative Feedback
1. Increased arterial pressure 2. Baroreceptors(sensor) 3. Inhibit
vasomotor center in medulla
4. Decreased impulses to heart &blood vessels 5.Decreased pumping activity of heart and V.D
6. Decreased blood pressure 7. Increased CO2 in tissue fluid
V 8. Excites
respiratory center
I 9. Increased rate of breathing
10. More CO2
is expired
11. Decreased CO2 in tissue fluid
Positive Feedback
The output is continually
enhanced or amplified so that the controlled variable continues to be moved in
the direction of the initial change or a pathway in which the response
reinforces the stimulus.
