Download Principals of General Zoology (Zoo-103)

Lecture 21: Animal physiology
Animal organ System & Homeostasis:
 Animal organs are usually composed of more than one cell type.
 Each organ performs a given function.
 The stomach is an organ composed of tissues that aid in the digestion
of food as part of the digestive system.
 Most organs have functions in only one organ-system.
Homeostasis: ‫ضبط وتنظيم البيئة الفسيولوجية الداخلية للجسم‬
 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 systems.
 Enzymes work best when a certain range of temperature and pH, 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.
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.
 Unicellular organisms such as paramecium, can dump wastes ‫يُخرج‬
‫ الفضالت‬outside the cell by exocytosis ‫اإلخراج الخلوي‬.
 Multicellular organisms, such as a human, dump wastes outside cells
then, carting away of these wastes outside the body is by both the
circulatory ‫ الدوري‬and excretory ‫ اإلخراجي‬systems.
 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 ‫( الغدد الصماء‬for longer-term responses, such as maintaining the
body levels of calcium).
Control Systems of homeostasis
‫األجهزة التي تتحكم في الثبات الفسيولوجي‬
A. Extrinsic control ‫التحكم الخارجي‬:
Most homeostatic systems are extrinsic; for example:
I. The nervous system:
Depends on sensors ‫ مناطق إحساس‬in 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.
II. The endocrine system:
Involves hormones. Sensors detect a change within the body and
send a message to an endocrine effector (for example; thyroid ),
which release hormones into the blood when blood minerals levels
are low.
B. Intrinsic control ‫التحكم الداخلي‬:
Involve only one organ or tissue. When muscles use more O2, and
also produce more CO2, intrinsic controls cause dilation ‫ تمدد‬of 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 body movement and body heat.
B.
Skeletal system:
Provides supports and protects the body and body parts, produces
blood cells, and stores minerals.
C.
Skin:
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.
E.
Circulatory system:
Transports
O2,
CO2,
nutrients,
waste
products,
immune
components, and hormones via the heart, capillaries, arteries, and
veins.
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.
H. Nervous System:
Coordinates and controls actions of internal organs and body
systems. Memory, learning, and conscious. Maintaining autonomic
functions )‫ الوظائف الذاتية (الال إرادية‬such 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.
J.
Reproductive System:
It is controlled by the endocrine system, and is responsible for
survival and perpetuation of the species. Produces gametes that
combine to produce the embryo.