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Cours
e O
bje
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Physiological concepts of homeostasis and control
mechanisms and to study the functions of body systems.
Transport of substances
Nerve cell signaling
Intracellular communication
Excitation contraction coupling
Cours
e O
bje
ctiv
es
3
Physiology of skeletal muscle
Cardiac muscle and the cardiac conduction system
Respiration and gas exchange
Endocrine system
Hemodynamic principles of cardiovascular
system
4
Physiology: the branch of biology that deals with the normal ----------------of living organisms and their parts.
A- structure
D- metabolismB- function
C- shape
Outc
om
e
Defi
nitio
n
5
PHYSIOLOGYGreek word
Physis-------nature
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 essential
for life
?
PHYSIOLOGY: THE STUDY OF THE FUNCTION AND THE REGULATION OF THE DIFFERENT ORGAN SYSTEMS OF THE BODY
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Type of cells, tissues, organ systems and
their functions
Levels of organization in the body
'
• The cell is the basic unit of both structure andfunction in a living being and is the smallestunit capable of carrying out the processesassociated with life
The tissues are group of cells of similar specializationAn organ is unit made up of several tissuetypesA body system is a collection of related organs
The body systems are packaged together intoa functional whole body(Organism)Organisms are independent living entities
•
•
•
•
•
Concept of Extracellular and Intracellular fluid
• Intracellular fluid—fluid contained withinthe cells of the body
Extracellular fluid—fluid outside the cells
the body and is the internal environment
all of
• ofin
which the cells live . It is composed of plasmaand interstitial fluid
Intracellular and extracellular fluid
INTRACELLULAR FLUID, ICF 40%TBW
EXTRACELLULARFLUID, ECF 20% TBW
40%
BLOOD/PLASMA4%
INTERSTITIALFLUID, 16%
TBW: Total Body Weight
Vander, Sherman, Luciano’s Human Physiology, 9th ed
EXTERNAL & INTERNAL ENVIRONMENT
Homeostasis
Homeo means “same”
Stasis means to “stand or stay”
WALTER CANNON (1871-1945)
HOMEOSTASIS: The relatively constant state of the composition of the internal environment, achieved through highly coordinated process.
1926
Hemostasis
• Pp12 fig 1-5 sherwood
Interdependent relationship of cells,systems and homeostasis
Factors homeostatically regulated
1.2.
3.
4.
5.
ConcentrationConcentration
Heart rate
pH
ConcentrationelectrolytesTemperature
of
of
nutrient molecules (B. Sugar)CO2 andO2
of water , salt and other
6.7. Volume and pressure (BP.)
Contribution of body systemsHomeostasis
to
••
•
•
•
•
•
•
•
•
•
TheTheTheTheTheTheTheTheTheThe
Circulatory SystemDigestive SystemRespiratory SystemUrinary SystemSkeletal SystemMuscular SystemIntegumentary SystemImmune SystemNervous SystemEndocrine System
Reproductive system is not essential for homeostasis andtherefore not essential for survival.
HOMEOSTATIC CONTROL SYSTEMS
FEEDBACK CONTROLLER
EFFECTORCONTROLLED
VARIABLE
SENSOR
SETPOINT
DISTURBANCE
+
-
CLOSED LOOP
RHOADES RA & TANNER GA. MEDICAL PHYSIOLOGY
+
-
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 pathway where the response opposes or removes the signal.
a
sed bloo
Negative FeedbackIncreased arterial pressure
Baroreceptors(sensor)
Inhibit vasomotor center in medulla
Decreased impulses to heart &blood vessels
Decreased pumping activity of heart and V.D
Decrea d pressure
rate
sed CO
Negative Feedback
Increased CO2 in tissue fluid
Excites respiratory center
Increased of breathing
More CO2 is expired
Decrea 2 in tissue fluid
CONTROL SYSTEMS
• NEGATIVE FEEDBACK• A DISTURBANCE ELICITS A RESPONSE THAT RESULTS IN AN EFFECT THAT IS
OPPOSITE THAT OF THE CHANGE
• eg. THERMOSTAT
CONTROL SYSTEMS
EXAMPLE: BODY TEMPERATURE
NORMAL, 37OC
w/o, 20OC, ROOM TEMPERATURE
with 36.5OC
ROOM TEMPERATURE
HEAT LOSS FROM BODY
BODY TEMPERATURE
CONSTRICTIONOF SKIN
BLOOD VESSELSCURLING
UP SHIVERING
HEAT PRODUCTION
RETURN OF BODY TEMPERATURETOWARD ORIGINAL VALUE
HEAT LOSS FROM BODY
CONTROL SYSTEMS
“SET POINT” OR BASELINE
RESETTING OF “SET POINT” IN RESPONSE
CONTROL SYSTEMS
• POSITIVE FEEDBACK
A STIMULUS ELICITS A RESPONSE THAT FURTHER INCREASES OR AMPLIFIES THE EFFECT OF THE INITIATING STIMULUS
HOMEOSTATIC CONTROL SYSTEMS
FEEDBACK CONTROLLER
EFFECTOR CONTROLLED
VARIABLE
SENSOR
SETPOINT
DISTURBANCE
+
CLOSED LOOP
RHOADES RA & TANNER GA. MEDICAL PHYSIOLOGY
CONTROL SYSTEMS
POSITIVE FEEDBACK
PHYSIOLOGIC USEFULNESS:• BLOOD CLOTTING
• PARTURITION (AT BIRTH)
http://www.biology.buffalo.edu/courses/bio130/medler/Lecture1.html
BLOOD CLOTTING
OXYTOCINRECEPTORS IN MYOMETRIUM
OXYTOCINSECRETION BYPOST’R PITUITARY
INCREASED STRETCHOF CERVIX
IN PARTURITION
UTERINECONTRACTIONS
PROSTAGLANDINSECRETION BY UTERUS
+
+
+
+
+
Positive Feedback
The output is continually enhanced or amplified so that the controlled variable continues to be moved in the direction of initial change or a pathway in which the response reinforces the stimulus.
the
Positive Feedback
Blood vessel ruptured
Clotting factors activated in clot itself
Activated clotting factors activate inactivated
clotting factors as an enzyme
Clot formed and bleeding stopped
ased fr
uterine
tocin
erine
Positive Feedback
Onset of labour
Oxytocin rele om hypothalmus
Increased contractions
Baby’s head pushed through cervix
Stretch of cervix
More oxy released
Increased ut contractions
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.
Can be classified as:
• Intrinsic (local controls) are inherent compensatory responses of an organ to a changeExtrinsic controls are responses of an organ that are triggered by factors external to the organ , namely, by the nervous and endocrine systems
•
Feedforward Mechanism
It brings about a compensatory response inanticipation ofvariable.
a change in a regulated
An example of a feedforward system is the preadaptation
for exercise, changing the activity of postural muscles and
of the vascular system in order to ready the body for the
movement when it occurs
HOMEOSTASIS
• Guyton & Hall. Textbook of Medical Physiology, 13th ed, Chap 1
• Vander, Luciano & Sherman. Human Physiology, 6th ed , Chap 1
