Transcript lec---20

Physiology
Animal Physiology
Animal organ System & Homeostsis
• Animal organs are usually composed of more than one cell type.
• Each organ typically performs a given function.
• The stomach is an organ composed of tissues that aid in the digestion of
food.
• Most organs have functions in only one organ-system.
• The stomach is involved only in the digestion of food as part of the
digestive system.
• Organ systems, such as the digestive system, are collections of organs that
perform a major function for the organism.
Homeostasis
The maintenance of a stable internal environment.
•
Homeostasis: is a term describe the physical and chemical parameters that an
organism must maintain to allow proper functioning of its component cells,
tissues, organs, and organ systems.
•
Enzymes function best when within a certain range of temperature and pH,
and that, cells must maintain a balance between having too much or too little
water in relation to their external environment.
•
Our body has a range of environmental (internal & external) parameters
within which it works best.
A. Multicellular organisms accomplish homeostasis by having organs and
systems that coordinate their homeostasis by the help of the nervous system.
B. Unicellular organisms accomplish homeostasis within a single cell by moving
materials into and out of the cell by regulation of the cell membrane and its
functioning.
Homeostasis
•
Unicellular organisms such as paramecium, can dump wastes
outside the cell by exocytosis.
•
Multicellular organisms, such as a human, dump wastes
outside cells then, carting away of these wastes outside the
body is by both the circulatory and excretory system.
•
Heat control is a major function of homeostatic conditions
that involves the skin, muscular and nervous & circulatory
systems.
•
The ultimate control of homeostasis is accomplished by the
nervous system (for rapid responses such as quick reflexes)
and the endocrine system (for longer-term responses, such as
maintaining the body levels of calcium).
Feedback Systems in Homeostasis
Biological Feedback
• Most physiological systems in the body use
feedback to maintain the body's internal
environment.
• Often this homeostatic control takes the
form of two types of feedback cycles:
I- Positive feedback control:
is used in some cases as input increases or
accelerates the response.
II- Negative feedback control mechanisms: is used
by most of the body's systems, the information
caused by the feedback causes a reverse
response.
Positive feedback:
Causes an amplification
of the stimulus by
the reaction.
Negative feedback:
Turns off the stimulus
that caused it in
the first place
Homeostasis
Parameters of
homeostasis
Internal components
Concentration of O2 and CO2
Internal environment
The extra-cellular fluid that
surrounds cells
pH of the internal environment
Plasma of the blood.
Concentration of nutrients
and waste products
Concentration of salts
Volume and pressure of
Extra-cellular fluid
Control Systems of homeostasis
A.
Extrinsic control:
Most homeostatic systems are extrinsic: they are controlled from outside the body. For
example:
I.
The nervous system:
depends on sensors in the skin or sensory organs to receive stimuli and transmit a
message to the spinal cord or brain. Signal is sent to an effector system, such as muscles
or glands, that effects the response to the stimulus.
II.
The endocrine system:
involves hormones. Sensors detect a change within the body and send a message to an
endocrine effector (parathyroid), which release hormones into the blood when blood
minerals levels are low resulting in raising the blood minerals levels.
B.
Intrinsic control:
Local controls usually involve only one organ or tissue. When muscles use more O2, and
also produce more CO2, intrinsic controls cause dilation of the blood vessels allowing
more blood into those active areas of the muscles. Eventually the vessels will return to
"normal".
Body Systems and Homeostasis
A. Muscular System: (facilitates movement and locomotion); The muscular
system produces body movements and body heat.
B. Skeletal System: provides support and protection, and attachment points
for muscles. The skeletal system provides rigid framework for movement.
It supports and protects the body and body parts, produces blood cells,
and stores minerals.
C. Skin or Integument: (the outermost protective layer); It prevents water
loss and protect the body from invasion of foreign microorganisms and
viruses.
D. Respiratory System:
moves O2 from the external environment into the internal environment;
also removes CO2. This occurs by exchanging gas between lungs and the
blood. It also maintains pH of the blood and facilitates exchange of CO2
and O2.
Body Systems and Homeostasis
E. Circulatory System:
transports O2, CO2, nutrients, waste products, immune components, and
hormones via the heart, capillaries, arteries, and veins. The lymphatic
system also transports excess fluids to and from circulatory system and
transports fat to the heart.
F. Immune System:
defends the internal environment from invading microorganisms and
viruses. It provides cells that aid in protection of the body from disease by
the antigen/antibody response.
G. Excretory System:
regulates volume of internal body fluids as well as eliminates metabolic
wastes from the internal environment. it removes organic wastes from the
blood. These wastes are then removed as urine. It is also responsible for
maintaining fluid levels.
Body Systems and Homeostasis
H. Nervous System:
coordinates and controls actions of internal organs and body systems.
Memory, learning, and conscious thought are the functions of the nervous
system. Maintaining autonomic functions such as heartbeat, breathing,
control of involuntary muscle actions.
I. Endocrine System:
works with the nervous system to control the activity of internal organs. it
secretes hormones that regulate body metabolism, growth, and
reproduction. Its organs communicate by chemical messages (hormones).
J. Reproductive System:
is mostly controlled by the endocrine system, and is responsible for survival
and perpetuation of the species. Organs of this system produce gametes that
combine in the female system to produce the next generation (embryo).
The Summary
Control Systems of homeostasis
Extrinsic control
nervous
system
endocrine
system
Reproductive
System
Muscular
System
Skin or
Integument
Intrinsic control
Respiratory
System
Skeletal
System
Excretory
System
Nervous
System
Circulatory
System
Immune
System
Endocrine
System