The Study of Body Function Lecture 1- foundation

Transcription

1 The Study of Body Function Lecture 1- foundation Prof. Hisham Al-Matubsi

2 Lecture 1 Outline Introduction to Physiology Homeostasis

3 HUMAN PHYSIOLOGY Physiology: study of how body works to maintain life Pathophysiology: how physiological processes are altered in disease or injury

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5 HOMEOSTASIS Is maintenance of fairly constant internal conditions Around physiological set points Maintained by negative feedback loops

6 NEGATIVE FEEDBACK LOOPS Sensor: Detects deviation from set point Integrating center: Determines response Effector: Produces response

7 Thermostat as example of homeostatic mechanism Control center Thermostat detects deviation from set point and signals effectors. Thermostat in room detects change. Effectors Heater turns off; air conditioner turns on. Room temperature rises above normal. Response Room temperature returns toward set point. too high Normal room temperature Thermostat set point. too low Room temperature Decreases. Response Room temperature returns toward set point. Thermostat in room detects change. Effectors Heater turns on; air conditioner turns off. Control center Thermostat detects deviation from set point and signals effectors.

8 Thermostat as example of homeostatic mechanismslide number: 2 Room temperature rises above normal. too high Normal room temperature Thermostat set point.

9 Thermostat as example of homeostatic mechanismslide number: 3 Thermostat in room detects change. Room temperature rises above normal. too high Normal room temperature Thermostat set point.

10 Thermostat as example of homeostatic mechanismslide number: 4 Control center Thermostat detects deviation from set point and signals effectors. Thermostat in room detects change. Room temperature rises above normal. too high Normal room temperature Thermostat set point.

11 Thermostat as example of homeostatic mechanism Slide number: 5 Control center Thermostat detects deviation from set point and signals effectors. Thermostat in room detects change. Effectors Heater turns off; air conditioner turns on. Room temperature rises above normal. too high Normal room temperature Thermostat set point.

12 Thermostat as example of homeostatic mechanism Slide number: 6 Control center Thermostat detects deviation from set point and signals effectors. Thermostat in room detects change. Effectors Heater turns off; air conditioner turns on. Room temperature rises above normal. Response Room temperature returns toward set point. too high Normal room temperature Thermostat set point.

13 Thermostat as example of homeostatic mechanism Slide number: 7 Normal room temperature Thermostat set point. Room temperature Decreases. too low

14 Thermostat as example of homeostatic mechanism Slide number: 8 Room temperature Decreases. Normal room temperature too low Thermostat set point. Thermostat in room detects change.

15 Thermostat as example of homeostatic mechanism Slide number: 9 Normal room temperature Thermostat set point. Room temperature Decreases. too low Thermostat in room detects change. Control center Thermostat detects deviation from set point and signals effectors.

16 Thermostat as example of homeostatic mechanism Slide number: 10 Normal room temperature Thermostat set point. Room temperature Decreases. too low Thermostat in room detects change. Effectors Heater turns on; air conditioner turns off. Control center Thermostat detects deviation from set point and signals effectors.

17 Thermostat as example of homeostatic mechanism Slide number: 11 Normal room temperature Thermostat set point. too low Room temperature Decreases. Thermostat in room detects change. Response Room temperature returns toward set point. Effectors Heater turns on; air conditioner turns off. Control center Thermostat detects deviation from set point and signals effectors.

18 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

19 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

20 Homeostatic mechanism regulates body temperature Control center The brain detects the deviation from the set point and signals effector organs. Slide number: 1 Thermoreceptors send signals to the control center. Effectors Skin blood vessels dilate and sweat glands secrete. Body temperature rises above normal. Response Body heat is lost to surroundings, temperature drops toward normal. too high Normal body Temperature 37 o C (98.6 o F) too low Body temperature drops below normal. Response Body heat is conserved, temperature rises toward normal. 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. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

21 Homeostatic mechanism regulates body temperature Slide number: 2 Body temperature rises above normal. too high Normal body Temperature 37 o C (98.6 o F)

22 Homeostatic mechanism regulates body temperature Slide number: 3 Thermoreceptors send signals to the control center. Body temperature rises above normal. too high Normal body Temperature 37 o C (98.6 o F)

23 Homeostatic mechanism regulates body temperature Slide number: 4 Thermoreceptors send signals to the control center. Control center The brain detects the deviation from the set point and signals effector organs. Body temperature rises above normal. too high Normal body Temperature 37 o C (98.6 o F)

24 Homeostatic mechanism regulates body temperature Slide number: 5 Control center The brain detects the deviation from the set point and signals effector organs. Thermoreceptors send signals to the control center. Effectors Skin blood vessels dilate and sweat glands secrete. Body temperature rises above normal. too high Normal body Temperature 37 o C (98.6 o F)

25 Homeostatic mechanism regulates body temperature Slide number: 6 Control center The brain detects the deviation from the set point and signals effector organs. Thermoreceptors send signals to the control center. Body temperature rises above normal. Effectors Skin blood vessels dilate and sweat glands secrete. Sweeting and increased blood flow cause increased heat loss Response Body heat is lost to surroundings, temperature drops toward normal. too high Normal body Temperature 37 o C (98.6 o F)

26 Homeostatic mechanism regulates body temperature Slide number: 7 Normal body Temperature 37 o C (98.6 o F) too low Body temperature drops below normal.

27 Homeostatic mechanism regulates body temperature Slide number: 8 Normal body Temperature 37 o C (98.6 o F) too low Body temperature drops below normal. Thermoreceptors send signals to the control center.

28 Homeostatic mechanism regulates body temperature Slide number: 9 Normal body Temperature 37 o C (98.6 o F) too low Body temperature drops below normal. Thermoreceptors send signals to the control center. Control center The brain detects the deviation from the set point and signals effector organs.

29 Homeostatic mechanism regulates body temperature Slide number: 10 Normal body Temperature 37 o C (98.6 o F) too low Body temperature drops below normal. Thermoreceptors send signals to the control center. 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.

30 Homeostatic mechanism regulates body temperature Slide number: 11 Normal body Temperature 37 o C (98.6 o F) too low Body temperature drops below normal. Thermoreceptors send signals to the control center. Effectors Skin blood vessels constrict and sweat glands remain inactive. 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.

31 Homeostatic mechanism regulates body temperature Slide number: 12 Thermoreceptors send signals to the control center. Normal body Temperature 37 o C (98.6 o F) too low Body temperature drops below normal. Response Body heat is conserved, temperature rises toward normal. Decreased skin blood flow helps retain heat Effectors Skin blood vessels constrict and sweat glands remain inactive. Effectors Muscle activity generates body heat. Control center The brain detects the deviation from the set point and signals effector organs. Shivering produced heat If body temperature continues to drop, control center signals muscles to contract involuntarily.

32 NEGATIVE FEEDBACK HORMONAL CONTROL OF BLOOD GLUCOSE

33 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.

34 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