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General physiology

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General physiology

  1. 1. GENERAL PHYSIOLOGY<br />Dr. Pavithran.P<br />Assistant Professor in Physiology<br />A J Institute of Medical Sciences, Mangalore<br />
  2. 2. What is Physiology<br />Physiology is the study of life, specifically, how cells, tissues, and organisms function. <br />Pronounced “fizzy-aw-low-jee”<br />2<br />
  3. 3. Q: Why do we shiver, when we feel cold?<br />To help us warm up, as shivering increases body temp <br />How does this happen – not answered<br />What is the cause – not answered<br />What will be its effect - answered<br />3<br />
  4. 4. 4<br />Temperature sensitive nerve cells detects fall in temperature<br />Impulses transmitted to brain <br />Hypothalamus<br />Brain areas gets activated<br />Involuntary, oscillating muscle contraction (Shivering)<br />Increases body temperature<br />
  5. 5. Internal environment&Homeostasis<br />5<br />
  6. 6. External environment – surrounding environment.<br />Amoeba- Unicellular Organism<br />Takes nutrients and expels waste – external environment <br />6<br />
  7. 7. Cells in human body – all does not have contact with external environment.<br />How do they support their vital activities?<br />Extra cellular fluid-the internal environment.<br />7<br />
  8. 8. Majority inside the cells –intracellular fluid (ICF).<br />1/3rd – out side the cells- Extracellular fluid (ECF).<br />ECF contains ions and nutrients<br />ECF – internal environment for the cells – Milieu Intérieur<br />8<br />
  9. 9. Milieu Interieur<br />Milieu- Environment<br />Interieur – Internal<br />19th French Physiologist.<br />Concept of the internal environment of an organism.<br />Blood- as the internal environment.<br />(1813-1878)<br />9<br />
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  11. 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<br />11<br />Walter Cannon<br />(1871–1945)<br />Homeostasis: maintenance of a constant internal environment. <br />An extension of Claude Bernard idea<br />
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  13. 13. Homeostatic mechanism<br />Three part mechanism<br />Receptor<br />Control center<br />Effector<br />13<br />
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  15. 15. The internal state of the body - dynamic equilibrium (balanced change).<br />There is a certain set point or average value for a given variable (such as 37°C for body temperature). <br />Conditions fluctuate slightly around this point.<br />15<br />
  16. 16. 16<br />
  17. 17. Regulatory Mechanism<br />
  18. 18. Negative feedback mechanism<br />Positive feedback mechanisms<br />Feedforward mechanism<br />18<br />
  19. 19. NEGATIVE FEEDBACK MECHANISM<br />
  20. 20. Most of the control mechanisms in human body<br />The body senses an internal change and activates mechanisms that reverse, or negate, that change.<br /><ul><li>Arterial blood pressure regulation
  21. 21. Increase in BP is detected by various mechanism that lead to a decrease in BP</li></ul>20<br />
  22. 22. 21<br /><ul><li>Increase in Co2 – increases ventilation- decreases Co2</li></li></ul><li>22<br /><ul><li>BODY TEMPERATURE REGULATION</li></li></ul><li>POSITIVE FEEDBACK MECHANISM<br />
  23. 23. A process in which the body senses a change and activates mechanisms that accelerate or increase that change.<br />Child birth (Parturition reflex)<br />Uterine contractions due to Oxytocin<br />Baby’s head pushes against the cervix -stretch<br />Sends impulse to the uterus<br />Stimulates further contractions of the uterus<br />Pushing the baby out.<br />Milk ejection reflex<br />24<br />
  24. 24. 25<br />
  25. 25. FEEDFORWARD MECHANISM<br />
  26. 26. Body responds in anticipation of a change in regulated variable.<br />In GIT- insulin secretion is increased<br />Insulin increases cellular uptake and storage of ingested nutrients after they are absorbed.<br />This limits the rise in blood sugar/nutrients after absorption<br />27<br />
  27. 27. Disruption<br />System malfunction<br />Homeostasis not maintained<br />Pathophysiology<br />Severe - death<br />28<br />

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