1. GENERAL PHYSIOLOGY Dr. Pavithran.P Assistant Professor in Physiology A J Institute of Medical Sciences, Mangalore

2. What is Physiology Physiology is the study of life, specifically, how cells, tissues, and organisms function. Pronounced “fizzy-aw-low-jee” 2

3. Q: Why do we shiver, when we feel cold? To help us warm up, as shivering increases body temp How does this happen – not answered What is the cause – not answered What will be its effect - answered 3

4. 4 Temperature sensitive nerve cells detects fall in temperature Impulses transmitted to brain Hypothalamus Brain areas gets activated Involuntary, oscillating muscle contraction (Shivering) Increases body temperature

5. Internal environment&Homeostasis 5

6. External environment – surrounding environment. Amoeba- Unicellular Organism Takes nutrients and expels waste – external environment 6

7. Cells in human body – all does not have contact with external environment. How do they support their vital activities? Extra cellular fluid-the internal environment. 7

8. Majority inside the cells –intracellular fluid (ICF). 1/3rd – out side the cells- Extracellular fluid (ECF). ECF contains ions and nutrients ECF – internal environment for the cells – Milieu Intérieur 8

9. Milieu Interieur Milieu- Environment Interieur – Internal 19th French Physiologist. Concept of the internal environment of an organism. Blood- as the internal environment. (1813-1878) 9

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11. Homeostasis:Homeo: same; stasis: stayThe word does not imply something set and immobile, a stagnation. It means a condition — a condition which may vary, but which is relatively constant 11 Walter Cannon (1871–1945) Homeostasis: maintenance of a constant internal environment. An extension of Claude Bernard idea

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13. Homeostatic mechanism Three part mechanism Receptor Control center Effector 13

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15. The internal state of the body - dynamic equilibrium (balanced change). There is a certain set point or average value for a given variable (such as 37°C for body temperature). Conditions fluctuate slightly around this point. 15

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17. Regulatory Mechanism

18. Negative feedback mechanism Positive feedback mechanisms Feedforward mechanism 18

19. NEGATIVE FEEDBACK MECHANISM

21. Increase in BP is detected by various mechanism that lead to a decrease in BP20

23. A process in which the body senses a change and activates mechanisms that accelerate or increase that change. Child birth (Parturition reflex) Uterine contractions due to Oxytocin Baby’s head pushes against the cervix -stretch Sends impulse to the uterus Stimulates further contractions of the uterus Pushing the baby out. Milk ejection reflex 24

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25. FEEDFORWARD MECHANISM

26. Body responds in anticipation of a change in regulated variable. In GIT- insulin secretion is increased Insulin increases cellular uptake and storage of ingested nutrients after they are absorbed. This limits the rise in blood sugar/nutrients after absorption 27

27. Disruption System malfunction Homeostasis not maintained Pathophysiology Severe - death 28