Human Physiology 1.pptx for cell physiology

Well presented by Dr Nafi'u at Federal university Dutse department of physiology

1. Human Physiology

2. Physiology – Introduction Claude Bernard (1813 – 1878) The first to establish scientific methodology in medicine Introduced experimental medicine and specifically “blind studies” to ensure objectivity Introduced “ Milieu interieur ” which was the initial concept of homeostasis “The constancy of the internal environment is the condition for a free and independent life” Furthered in the next century by William Bradford Canon

3. Physiology – Introduction Walter Bradford Cannon (1871 – 1945) Chaired the Department of Physiology at Harvard Medical School Coined the term “fight or flight” Did work with x-rays and different metals to improve x-ray quality of bowels (today’s barium meal is a direct result) Given credit for concept of homeostasis, published it in 1932

4. Physiology - Introduction Organization Homeostasis & Controls Communication

5. Organizational Hierarchy in Biology atoms molecules cells tissues organs organ systems organisms population community ecosystem biosphere Chemistry Ecology Physiology Cell biology Molecular biology

6. Homeostasis The maintenance of physiological parameters within the body/cell “ homeo ” = similar or like “ stasis ” = condition or state Provides a teleological answer to questions Acts in a mechanistic way Components Process Types

7. Homeostasis Components Receptor Monitors the controlled condition Creates input signal Control center Processes input signal Makes decision Creates output signal Effector Returns controlled condition to normal state in one of two ways receptor control center effector input signal output signal

8. Homeostasis Functional unit in homeostasis external change internal change change results in disruption of homeostasis compensation for change is attempted (feedback processes) compensation fails compensation succeeds illness/disease Wellness/health Process:

9. Homeostasis Types of homeostasis maintenance pathways Negative Feedback Loop Mechanisms Common Reverse the change in the regulated variable back to normal May be local or long distance Require reflex pathways Positive Feedback Loop Mechanisms Rare Enhances the stressor in a cascading effect until stressor is removed, causing regulated variable to return to normal Feedforward Controls Aid in homeostatic processes by “anticipating” events, rather than waiting for them to happen and then responding

10. Homeostasis Negative Feedback Control Example: blood Ca 2+ levels regulated variable blood levels of calcium normal value 8.5 – 10.5 mg/dl drop in blood levels of Ca 2 + rise in blood levels of Ca 2 + PTH secretion is stimulated PTH secretion is inhibited  Vit D synthesis  Ca 2+ release from bone blood Ca 2+ levels normalize Ca 2+ uptake in GI tract Ca 2+ reabsorption in kidney  Vit D synthesis  Ca 2+ uptake by bone Ca 2+ uptake in GI tract Ca 2+ secretion by kidney change causes

11. Homeostasis Other Negative Feedback Examples? Blood glucose levels Body temperature maintenance pH controls Blood pressure regulation Ventilation rates Thyroid hormone levels Cell cycle GI motility & secretion CO 2 levels Receptors in plasma membrane Urine concentration/ dilution

12. Homeostasis positive feed back control example: childbirth (parturition) Regulated variable female reproductive tract Change End of term fetus, uterus contracts, increases pressure on the cervix pressure causes release of oxytocin Oxytocin causes increased contraction of the uterus & relaxation of cervix Process continues until the cervix is dilated enough and the uterus contractions expel the fetus

13. Homeostasis Other examples of positive feedback loops? Some enzyme production Hemostasis (blood clotting) Lactation

14. Homeostasis Feedforward loops?

15. Communication Major theme in physiology Forms Electrical Chemical Between Cell/cells Tissues Organs… Communication allows for the integration of physiology!

16. Cell Physiology The “Inner Life of a Cell” Components and their functions Cell to Cell Junctions - Forming Tissues How it’s Integrated

17. Cell Components What are the basic components of a cell? cell membrane nucleus cytoplasm cytosol organelles

18. Cell Components The Cell Membrane What does the cell membrane do? Creates separation between ECF vs. ICF Creates fluid compartments Regulates ECF – ICF exchange Allows for communication Provides structural support for cell and tissues

19. Cell Components The Cell Membrane The physical barrier Formed by the tail to tail arrangement of the phospholipid molecules Self assembles into miceles liposomes bi-layer membranes

20. Cell Components The Cell Membrane How does a barrier become a regulator? By being having a polar surface By specialized membrane components hydrophillic heads hydrophillic heads hydrophobic tails

21. Cell Components The Cell Membrane Other phospholipid bilayer membrane components cholesterol sphingolipids Membrane proteins Glycoconjugates ECF ICF Na +

22. Cell Components The Cell Membrane Sphingolipids Group of membrane lipids with larger “heads” Involved in cell signal transduction by forming caveolae cell-cell communication Endocytosis & uptake of viruses and bacteria Form “lipid rafts” – more cholesterol fatty acid OH NH CH 2 O R O sphingosine R groups – determine functionality

23. Cell Components The Cell Membrane Membrane Proteins 3 categories transmembrane proteins peripheral proteins lipid anchored ( amphitropic ) proteins

24. Cell Components The Cell Membrane Transmembrane Proteins Types: Most common type in mammalian cells are alpha helical proteins Also beta barrels in mitochondria Single and polytopic alpha helical membrane proteins Beta barrel helical membrane proteins

25. Cell Components The Cell Membrane Functions of transmembrane proteins Transport function Enzyme function Gated Ion channel formation Receptor function/signal transduction

26. Cell Components The Cell Membrane Peripheral Proteins – attachments to the phospholipid bi-layer interaction with alpha helix in transmembrane protein (not shown) interaction by a hydrophobic loop interaction by a covalently bound membrane lipid ( forms many sphingolipids) electrostatic or ionic interactions with membrane lipids

27. Cell Components The Cell Membrane Peripheral Protein Functions Enzyme function Mediate chemical reactions Structural Mediate attachment Transporters Between/among cell membrane proteins Electron carriers In electron transport chain Regulators Such as apoptosis