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Human Physiology 1.pptx for cell physiology
- 1.
- 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 inBiology atoms molecules cells tissues organs organ systems organisms population community ecosystem biosphere Chemistry Ecology Physiology Cell biology Molecular biology
- 6. Homeostasis • The maintenanceof 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 unitin 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 ofhomeostasis 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 FeedbackControl Example: blood Ca2+ levels regulated variable blood levels of calcium normal value 8.5 – 10.5 mg/dl drop in blood levels of Ca2+ rise in blood levels of Ca2+ PTH secretion is stimulated PTH secretion is inhibited Vit D synth esis Ca2+ release from bone blood Ca2+ levels normalize Ca2+ uptake in GI tract Ca2+ reabsorptio n in kidney Vit D synth esis Ca2+ uptake by bone Ca2+ uptake in GI tract Ca2+ secretion by kidney change causes
- 11. Homeostasis • Other NegativeFeedback Examples? Blood glucose levels Body temperature maintenance pH controls Blood pressure regulation Ventilation rates Thyroid hormone levels Cell cycle GI motility & secretion CO2 levels Receptors in plasma membrane Urine concentration/ dilution
- 12. Homeostasis • positive feedback 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 examplesof positive feedback loops? Some enzyme production Hemostasis (blood clotting) Lactation
- 14.
- 15. Communication • Major themein 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 • Whatare the basic components of a cell? • cell membrane • nucleus • cytoplasm • cytosol • organelles
- 18. Cell Components TheCell 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 TheCell 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 TheCell Membrane • How does a barrier become a regulator? 1. By being having a polar surface 2. By specialized membrane components hydrophillic heads hydrophillic heads hydrophobic tails
- 21. Cell Components TheCell Membrane • Other phospholipid bilayer membrane components • cholesterol • sphingolipids • Membrane proteins • Glycoconjugates ECF ICF Na+
- 22. Cell Components TheCell 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 CH2O R O sphingosine R groups – determine functionality
- 23. Cell Components TheCell Membrane • Membrane Proteins • 3 categories • transmembrane proteins • peripheral proteins • lipid anchored (amphitropic) proteins
- 24. Cell Components TheCell 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 TheCell Membrane • Functions of transmembrane proteins • Transport function • Enzyme function • Gated Ion channel formation • Receptor function/signal transduction
- 26. Cell Components TheCell 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 TheCell 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