The Study of Body Function Lecture 1- foundation Prof. Hisham Al-Matubsi
The Study of Body Function Lecture 1- foundation
Prof. Hisham Al-Matubsi
Lecture 1 Outline
Introduction to Physiology
Homeostasis
HUMAN PHYSIOLOGY
Physiology: study of how body works to maintain life
Pathophysiology: how physiological processes are altered in
disease or injury
HOMEOSTASIS
Is maintenance of fairly constant internal conditions
Around physiological set points
Maintained by negative feedback loops
NEGATIVE FEEDBACK LOOPS
Sensor: Detects deviation from set point
Integrating center: Determines response
Effector: Produces response
Control center Thermostat detects deviation from set point and signals effectors.
Receptors Thermostat in room detects change.
Effectors Heater turns off; air conditioner turns on.
Stimulus Room temperature rises above normal.
Response Room temperature returns toward set point.
too high
Normal room temperature
too low
Stimulus Room temperature Decreases.
Response Room temperature returns toward set point.
Receptors Thermostat in room detects change.
Effectors Heater turns on; air conditioner turns off.
Control center Thermostat detects deviation from set point and signals effectors.
Thermostat set point.
Thermostat as example of homeostatic mechanism
Thermostat as example of homeostatic mechanismSlide number: 2
Stimulus Room temperature rises above normal.
too high
Normal room temperature
Thermostat set point.
Thermostat as example of homeostatic mechanismSlide number: 3
Receptors Thermostat in room detects change.
Stimulus Room temperature rises above normal.
too high
Normal room temperature
Thermostat set point.
Thermostat as example of homeostatic mechanismSlide number: 4
Control center Thermostat detects deviation from set point and signals effectors.
Receptors Thermostat in room detects change.
Stimulus Room temperature rises above normal.
too high
Normal room temperature
Thermostat set point.
Thermostat as example of homeostatic mechanism Slide number: 5
Control center Thermostat detects deviation from set point and signals effectors.
Receptors Thermostat in room detects change.
Effectors Heater turns off; air conditioner turns on.
Stimulus Room temperature rises above normal.
too high
Normal room temperature
Thermostat set point.
Thermostat as example of homeostatic mechanism Slide number: 6
Control center Thermostat detects deviation from set point and signals effectors.
Receptors Thermostat in room detects change.
Effectors Heater turns off; air conditioner turns on.
Stimulus Room temperature rises above normal.
Response Room temperature returns toward set point.
too high
Normal room temperature
Thermostat set point.
Thermostat as example of homeostatic mechanism Slide number: 7
Normal room temperature
too low
Thermostat set point.
Stimulus Room temperature Decreases.
Thermostat as example of homeostatic mechanism Slide number: 8
Normal room temperature
too low
Thermostat set point.
Stimulus Room temperature Decreases.
Receptors Thermostat in room detects change.
Thermostat as example of homeostatic mechanism Slide number: 9
Normal room temperature
too low
Thermostat set point.
Stimulus Room temperature Decreases.
Receptors Thermostat in room detects change.
Control center Thermostat detects deviation from set point and signals effectors.
Thermostat as example of homeostatic mechanism Slide number: 10
Normal room temperature
too low
Thermostat set point.
Stimulus Room temperature Decreases.
Effectors Heater turns on; air conditioner turns off.
Receptors Thermostat in room detects change.
Control center Thermostat detects deviation from set point and signals effectors.
Thermostat as example of homeostatic mechanism Slide number: 11
Normal room temperature
too low
Thermostat set point.
Stimulus Room temperature Decreases.
Response Room temperature returns toward set point.
Effectors Heater turns on; air conditioner turns off.
Receptors Thermostat in room detects change.
Control center Thermostat detects deviation from set point and signals effectors.
By turning heater on (antagonistic effect) i.e activity of effector is in negative or reverse negative feedback loop Negative feedback: Effectors are activated by changes in the internal environment and inhibitory actions of the effectors serve to counteract these changes and maintain a state of internal constancy or homeostasis
HOMEOSTASIS
Regulatory mechanisms:
Intrinsic control is built into organ being regulated
Extrinsic control comes from outside of organ
By nervous or endocrine systems
E.g. nervous control of body temperature
Homeostatic mechanism regulates body temperature
Slide number: 1
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Control center The brain detects the deviation from the set point and signals effector organs.
Receptors Thermoreceptors send signals to the control center.
Effectors Skin blood vessels dilate and sweat glands secrete.
Stimulus Body temperature
rises above normal.
Response Body heat is lost to surroundings,
temperature drops toward normal.
too high
too low
Normal body
Temperature
37oC (98.6oF)
Stimulus Body temperature
drops below normal.
Response Body heat is conserved,
temperature rises toward normal.
Receptors Thermoreceptors send signals to the control center.
Effectors Skin blood vessels constrict and sweat glands remain inactive.
Effectors generates body heat.
Control center The brain detects the deviation from the set point and signals effector organs.
If body temperature continues to drop, control center signals muscles to contract involuntarily.
Homeostatic mechanism regulates body temperature Slide number: 2
Stimulus Body temperature rises above normal.
too high
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 3
Receptors Thermoreceptors send signals to the control center.
Stimulus Body temperature rises above normal.
too high
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 4
Control center The brain detects the deviation from the set point and signals effector organs.
Receptors Thermoreceptors send signals to the control center.
Stimulus Body temperature rises above normal.
too high
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 5
Control center The brain detects the deviation from the set point and signals effector organs.
Receptors Thermoreceptors send signals to the control center.
Effectors Skin blood vessels dilate and sweat glands secrete.
Stimulus Body temperature rises above normal.
too high
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 6
Control center The brain detects the deviation from the set point and signals effector organs.
Receptors Thermoreceptors send signals to the control center.
Effectors Skin blood vessels dilate and sweat glands secrete.
Stimulus Body temperature rises above normal.
Response Body heat is lost to surroundings, temperature drops toward normal.
too high
Normal body Temperature 37oC (98.6oF)
Sweeting and increased blood flow
cause increased heat loss
too low
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 7
Stimulus Body temperature drops below normal.
Receptors Thermoreceptors send signals to the control center.
too low
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 8
Stimulus Body temperature drops below normal.
Receptors Thermoreceptors send signals to the control center.
too low
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 9
Stimulus Body temperature drops below normal.
Control center The brain detects the deviation from the set point and signals effector organs.
Receptors Thermoreceptors send signals to the control center.
too low
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 10
Stimulus Body temperature drops below normal.
Control center The brain detects the deviation from the set point and signals effector organs.
If body temperature continues to drop, control center signals muscles to contract involuntarily.
Effectors Skin blood vessels constrict and sweat glands remain inactive.
Receptors Thermoreceptors send signals to the control center.
too low
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 11
Stimulus Body temperature drops below normal.
Effectors Muscle activity generates body heat.
Control center The brain detects the deviation from the set point and signals effector organs.
If body temperature continues to drop, control center signals muscles to contract involuntarily.
Effectors Skin blood vessels constrict and sweat glands remain inactive.
Receptors Thermoreceptors send signals to the control center.
too low
Normal body Temperature 37oC (98.6oF)
Homeostatic mechanism regulates body temperature Slide number: 12
Stimulus Body temperature drops below normal.
Response Body heat is conserved, temperature rises toward normal.
Effectors Muscle activity generates body heat.
Control center The brain detects the deviation from the set point and signals effector organs.
If body temperature continues to drop, control center signals muscles to contract involuntarily.
Decreased skin blood flow
helps retain heat
Shivering produced heat
NEGATIVE FEEDBACK HORMONAL CONTROL OF
BLOOD GLUCOSE
Homeostasis Sate of relative constancy of internal environment. To maintain homeostasis, such environmental changes or stimuli are detected, conveyed via nervous to the spinal cord and brain. The incoming information is then processed and conveyed by nervous to the muscle and glands of the body causing the muscle to contract or relax and glands to secrete or not secrete their product.
POSITIVE FEEDBACK LOOP
Activation of one clotting factor results in activation of many other factors in a positive feedback cascade. (Amplification of an initial changes)
Another example: Oxytocin from pituitay gland →stimulates
contractions of uterus → Contraction of uterus →stimulates more secretion of oxytocin → more contractions of uterus and so on