General physiology

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

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

10. 10

11. Homeostasis: Homeo: same; stasis: stay The 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 Homeostasis: maintenance of a constant internal environment . An extension of Claude Bernard ide a (1871–1945)

12. 12

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

14. 14

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

16. 16

17. Regulatory Mechanism

18. Negative feedback mechanism Positive feedback mechanisms Feedforward mechanism 18

19. NEGATIVE FEEDBACK MECHANISM

20. Most of the control mechanisms in human body The body senses an internal change and activates mechanisms that reverse, or negate, that change. Arterial blood pressure regulation Increase in BP is detected by various mechanism that lead to a decrease in BP 20

21. 21 Increase in Co2 – increases ventilation- decreases Co2

22. 22 BODY TEMPERATURE REGULATION

23. POSITIVE FEEDBACK MECHANISM

24. 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

25. 25

26. FEEDFORWARD MECHANISM

27. 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

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