Fluid and Acid-Base Balance

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Fluid and Acid-Base Balance
2013-11-12 20:54:10
Biol 224

Fluid and acid-base balance lecture study guid
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  1. What proportion of an adult female's body is made up of solids? How about water?
    • Solids 45%
    • Water 55%
  2. The proportion of an adult male's body is made up of water? How about solids?
    • Water 60%
    • Solids 40%
  3. How will the kidneys respond to decrease in blood PH?
    Reabsorbed HCO3- and secrete H+
  4. How the kidneys will respond to an increase of PH?
    Reabsorb H+ and secrete HCO3-
  5. How the rate of respiration will respond to changes in PH?
    • Because the presence of CO2 causes H2O in the body to disassociate into bicabonate and H+ , will lower the PH
    • When PH gets too low, the rate of respiration increases, so we can get rid of CO2 quicker and raise the PH back to normal.
  6. How bicarbonate buffer system will respond to change in PH?
    • in response to high PH
    • CO2 combine with H2O and become H2CO3 Then it disassociate to HCO3- and H+
    • The H+ will reduce the pH
    • In response to low PH:
    • HCO3- bind to H+ and become H2CO3 then it disassociate to H2O and CO2
    • The CO2 will be exhaled and H2O has no effect on pH but the removal of H+ will rise the PH.
  7. How can we use hemoglobin as a buffer?
    • During CO2 transport:
    •  CO2→H2O→H2CO3→HCO3- + H+
    • Hemoglobin bind to H+.
    • That prevent decrease in PH
    • This process is reversed in the lung when CO2is exhaled,
  8. How does protein buffer respond to decrease in PH?
    • The amino group of the amino acid will bind to H+
    • That will decrease the PH
  9. How will protein buffer will respond to increase in PH?
    • The carboxyl group of the amino acid will release H+
    • That will decrease the PH
  10. How phosphate buffer respond to a decrease in PH?
    • HPO42- will bind to H+ and become H2PO4- .
    • That will increase the PH.
  11. How phosphate buffer respond to an increase in PH?
    • H2PO4- (dihydrogen phosphate) will release H+ and become HPO42- (monohydrogen phosphate)
    • That will decrease the PH (make it more acidic)
  12. What is a buffer?
    A substance that opposes (stabilizes) change in PH by either bind or release H+
  13. How do we loose hydrogen ions?
    • Exhalation of CO2 (accumulation of CO2 cause elevation of H+)
    • H+ secreted (exerted) by the kidneys.
    • Buffers temporarily bind to H+
  14. How do we gain hydrogen ions?
    • By metabolic activities that produce acids.
    • for example, aerobic respiration produce CO2 that become carbonic acid and lactic acid from fomentation.
  15. At what PH are we considered to be in acidosis? How about alkalosis?
    • Acidosis: PH below 7.35.
    • Alkalosis: PH above 7.45
  16. How does aldosterone effects the body?
    • Increase Na+ re-absorption
    • Increase K+ secretion
    • Stimulate salt receptors (makes you want to eat salty foods)
    • as result, blood Na+ will rise and water follow by osmosis. That will raise blood volume and blood pressure.
  17. What effect does ADH have on water balance?
    • Decrease urination
    • Increase thirst
    • That will increase fluid consumption and decrease fluid excretion. both together will increase blood volume and blood pressure.
  18. What kind of fluid shift will occur if the osmotic concentration of the ECF increases? How about if it decreases?
    • Increase O/C of  ECF : fluid shift from ICF into ECF
    • Decrease O/C of ECF:fluid shift from ECF into ICF
  19. Which are the various ways that we can gain and lose water?
    • Gain:
    • Primary by water absorption via the GI tract (small and large intestines)
    • By osmotic gradient as nutrient & ions absorbed, water follow.
    • Loss:
    • Mainly by urination
    • also by other routes such as exhalation, sweat, and feces,
  20. Where/How we gain and lose water?
    • Out of 2500 mL of water
    • Gain: 2600 mL fluid ingested, 700 mL food ingested, and 200 mL metabolic water.
    • Lose: 1500 mL in urination, 600 mL via skin, 300 mL in the lungs (exhalation), and 100 mL via GI tract (feces)
  21. How is the water in the ECF distributed?
    • 80% in the interstitial fluid
    • 20% in the plasma
  22. What proportion of water is in the ECF? How about the ICF?
    • 1/3 in the ECF (extracellular fluid)
    • 2/3 in the ICF (intracellular fluid)
  23. What accounts for the difference in water content between males and females?
    • Muscle mass in males is grater then females.
    • Skeletal muscle = 75% water
    • Adipose tissue = 10% water
  24. What will occur if someone over-hydrated?
    • cause by excessive blood loss, vomiting or diarrhea coupled with intake of pure water→
    • decrease concentration of Na+ in blood & IF→

    • decrease osmolarity of plasma & IF→
    • fluid shift from ECF into ICF→
    • Water intoxication (cells will pop from over fill)→
    • Convulsion, coma and possible death.
  25. Understand the changes that occur in response to dehydration.
    • two routs happens simultaneously.
    • rout 1:
    • Blood volume decrease→blood pressure decrease→Renin released→angoitensine II released.
    • rout 2:
    • osmolarity of body fluid increased→stimulate osmsoceptors
    • Both routes lead to the following:
    • Stimulates thirst center→increase thirst→increase water intake→increase water level.
  26. What is the normal range of blood PH?
    Between 7.35 and 7.45