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38 Cards in this Set
- Front
- Back
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What is water budget?
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Intake=Output therefore fluid balance
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Intake/Day
Ingested fluid drink food metabolism |
2500 ml
2300 ml 1600 ml 700 ml 200 ml |
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Output/day
urine feces skin sweat diffusion lungs lung & diffusion thru skin |
2500 ml
1500 ml 200 ml 500 ml 100 ml 400 ml 300 ml insensible loss |
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Two mechanisms for fluid balance that can adjust are?
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intake to match output
out put to match intake |
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Regulation of intake to match output
If H20 intake less than H20 output |
Dehydration
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Two types of dehydration
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local dehydration
systemic dehydration (physiological dehydration) |
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H20 deficit can only be made up by?
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Drinking
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Other H20 gain mechanisms not concerned with fluid balance are?
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Food intake--hunger mechanism
carbohydrate mechanism--enery (ATP)balance |
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Local dehydration is called what?
Not the same as systemic dehydration. Wet oral mucosa "thirst" relieved |
"Dry Mouth"
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Systemic Dehydration
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the thirst mechanism
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If intake is less than output then what is the ECF & Plasma?
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Decreased ECF Volume & Increased Plasma
detected by osmoreceptors in hypothalamus the hypothalamus causes decreased saliva secretion causing thirst synthesis ie--brain telling you to drink |
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If you ingest water what happens to the ECF & plasma osmolarity?
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Increases the ECF volume and decreases the plasma osmolarity
receptors in the stomach and small intestine "meter" intake and tell the hypothalamus when enough H20 has been ingested |
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If intake is less that output for an extended period of time what happens?
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Can't maintain fluid balance
Some output obligatory (ie always losing H20) 440 ml/day minimum urinary loss--excretion of wastes also insensible loss |
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Regulation of output to match intake--What is the only thing that can be controlled?
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Urinary loss can be controlled other H20 mechanisms not concerned with fluid balance.
sweat--temp regulation fecal loss--normally consistent insensible loss--uncontrollable |
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Under Regulation of output to match input if the intake is less than output what happens to the ECF vol. & Plasma
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Decrease in ECF vol. & increase in plasma
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What does the hypothalamus cause?
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aldosterone secretion by the adrenal cortex and ADH secretion by the pituitary gland
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What does aldosterone do?
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Promotes the reabsortion of Na+ from filtrate moving thru kidney tubules
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What does the remaining filtrate do?
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Becomes hypotonic to blood in the capillaries surrounding the tubules
ie--a gradient for Na+, therefore H20 has been created |
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What does ADH do?
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Increases the permeability of kidney tubules walls to H20
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What does the H20 do in this instance?
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H20 now follows Na+ into the capillaries surrounding tubules then increases reabsorption of H20 and decreases urinary loss
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Starlings law of capillaries is what?
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The movement between plasma and the IF
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What four pressures does H20 movement depend on?
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2 hydrostatic (pushing) pressures
2 colloid osmotic (pulling) pressures |
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What does hydrostatic pressure do?
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Pushes water accross the capillary wall.
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What is BHP and what does it do?
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Blood hydrostatic pressure (BHP)--pushes water our of the capillary into the Interstitial Fluid (IF) This is done mostly at the ARTERIOLE end of the capillary
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What is IFHP and what does it do?
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Interstitial fluid hydrostatic pressure (IFHP) opposes BHP due to the water in the IF
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What is colloid osmotic pressure?
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Colloid osmotic pressure "pulls" H20 across the capillary wall
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What is BCOP and what does it do?
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blood colloid osmotic pressure (BCOP) "pulls" H20 back into the capillary from the IF. Due to mostly plasma protiens--main determinates of plasma osmolarity. Mainly at the VENULE end of the capillary. ie--blood is hypertonic by the end of the capillary
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What is IFCOP and what does it do?
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Interstitial osmotic pressure opposes BCOP (blood colloid osmotic pressure) due to the solutes in the IF
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What is effective filtration pressure?
EFP=[BHP+IFCOP]-[IFHP+BCOP] |
EFP(arterial end of capillary)=8 mmHg
EFP (venule end of capillary)=7mmHg therefore, almost all of H20 that is forced out re-enters capillary the remainder stays in the IF and the IF constantly enters the lymph capillaries--lymph |
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What happens if you increase the BHP during effective filtration pressure?
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H20 goes from the plasma to the IF
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What happens if you increase the BCOP during effective filtration pressure?
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H20 goes from the IF to the plasma
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What happens during H20 movement between the IF & ICF?
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Colloid osmotic pressures now have more movement
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The COP is directly related to what?
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The electrolyte concentration across the membrane, but Na+ and K+ is the most important.
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What two factors determine the electrolyte concentration gradients, therefore causing H20 distribution between IF & ICF?
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selectively permeable membrane and Na-K pump
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What is electrolyte balance important for?
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Body fluid osmolarity.
H20 movement between fluid compartments. acid-base balance neuromuscular irritability enzyme function |
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What can't electrolytes be?
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synthesized
consumed by a reaction |
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What does electrolyte balance depend on?
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ingestion
excretion (by the kidneys) |
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What balance is most important with electrolyte balance?
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Na+ balance is the most important
other electrolyte balance mechanisms are linked to Na+ |
