homeostais and body_fluid

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homeostais and body_fluid

  1. 1. HomeostasisHomeostasis
  2. 2.  Physiology: study the functions of living things
  3. 3. Body Fluid Compartments  Cells contained in watery internal environment: life- sustaining exchanges occur  Extracellular fluid (ECF): Fluid outside the cells Plasma Interstitial fluid  Intracellular fluid (ICF): Fluid contained within the cells
  4. 4. Homeostasis  Maintenance of a relatively stable internal environment  Internal environment is the extracellular fluid  Essential for survival and function of all cells
  5. 5. Homeostasis  Factors Homeostatically Regulated:  Concentration of nutrient molecules  Concentration of O2 and CO2  Concentration of waste products  Concentration of water, salt, and other electrolytes  Volume and pressure  pH  Temperature
  6. 6. Homeostasis  All the systems of the body work together to maintain homeostasis:  Gastrointestinal, Respiratory systems Obtaining nutrients and O2  Circulatory system  Transport  Respiratory, Renal systems  Removal of waste and metabolic end products  Nervous and Endocrine systems Regulation
  7. 7. Homeostasis
  8. 8. Homeostatic Control Systems  Functionally interconnected network of body components that operate to maintain a given factor in the internal environment relatively constant around an optimal level
  9. 9. Homeostatic Control Systems Components: Sensor: Detects deviation from set point Integrating (control) center: Compares input with set point & determines response Effecter: Produces response
  10. 10. Homeostatic Control Systems  Feedforward:  Term used for responses made in anticipation of a change  Feedback:  Refers to responses made after change has been detected  Types of feedback systems  Negative Feedback  Positive Feedback
  11. 11. Homeostatic Control Systems  Negative Feedback:  Primary type of homeostatic control  Opposes initial change
  12. 12. Homeostatic Control Systems  Negative Feedback:
  13. 13. Homeostatic Control Systems  Positive Feedback:  amplifies an initial change  An output is enhanced  A controlled variable moves in the direction of an initial change
  14. 14. Homeostatic Control Systems  Positive Feedback:  One example occurs during the birth of a baby
  15. 15. Body FluidBody Fluid
  16. 16. Body fluid  On average, body fluids constitute 60% of total body weight  In the average 70 Kg adult male is about 42 L
  17. 17. Body fluid  Variation in water content:  Variation due to age: total body water (TBW)  with increasing age, by age of 60 years it becomes 50 %  Variation between tissues:  Most tissues are water-rich and contain 70-80% water  Plasma contains >90% water  Fat is the driest tissue of all, having only 10% water content  Variation between individuals:  TBW in a standard male is 60% of his body weight, while in female, its 55%, due to higher fat content  Obese adults have lower percentage
  18. 18. Body Fluid Compartments  TBW represent about 60% of total body weight:  Intracellular fluid (ICF):  fluid within the cells  about 2/3 of TBW (40%)  Extracellular fluid (ECF):  fluid outside the cells  About 1/3 of TBW (20%)
  19. 19. Body Fluid Compartments
  20. 20. Body Fluid Compartments
  21. 21. Body Fluid Compartments
  22. 22. Body Fluid Compartments
  23. 23. Body Fluid Compartments
  24. 24. Body Fluid Compartments ICF differs considerably from ECF
  25. 25. Body is in fluid balance  Daily intake of water:  Fluid intake (1.250 mL/day)  Food intake (1000 ml/day)  Metabolically produced H2O (350mL/day)  Daily loss of body water:  Insensible water loss (900ml/day)  Fluid loss in sweat (100ml/day)  Water loss in feces (100ml/day)  Water loss by kidney (1500 ml/day) Total intake (2600ml/day) Total output (2600ml/day)
  26. 26. Body is in fluid balance  In a steady state, the osmolarity in ECF is the same as in ICF  Normally, cells neither shrink or swell because intracellular and interstitial fluids have the same osmolarity (280 mmol/L)  Increasing osmolarity of ECF draws water out of cells and cells shrink  Decreasing osmolarity of ECF draw water inside of cells and causes cells to swell

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