Answers
What happens to the percentage of body water through the lifespan? - ANS Newborns; 75-
90%
Childhood; 60-65%
Adults; 60%
Older adults; declines with age
Why do older adults experience a decrease in body percentage of water? - ANS - increased
adipose tissue
- decreased muscle mass
- renal decline
- diminished thirst
What is the definition of osmotic force? - ANS Amt. of hydrostatic pressure required to
oppose the osmotic movement of water.
What is filtration? - ANS movement of fluid from the capillary into the interstitial space
What is reabsorption? - ANS movement of fluid from interstitial space into the capillary
What is capillary hydrostatic pressure? - ANS (blood pressure) facilitates the outward
movement of water from the capillary to the interstitial space
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,What is capillary oncotic pressure? - ANS Water pulling
attracts water from the interstitial space back into the capillary osmotically
What is interstitial hydrostatic pressure? - ANS Water pushing.
facilitates the inward movement of water from the interstitial space into the capillary
What is interstitial oncotic pressure? - ANS water pulling
attracts water from the capillary into the interstitial space osmotically.
What is Starlings hypothesis? - ANS Net filtration = forces favoring filtration - forces opposing
filtration
What forces favor filtration? - ANS 1. Capillary hydrostatic pressure (blood pressure)
2. interstitial oncotic pressure (water pulling)
What forces oppose filtration? - ANS 1. Plasma (capillary) oncotic pressure (water pulling)
2. Interstitial hydrostatic pressure
What is the major force of filtration and reabosoprtion? - ANS capillary pressures
What happens at the arteriole end of the capillary in terms of fluid forces? - ANS hydrostatic
pressure > interstitial oncotic pressure = water into the insterstitial space
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, FILTRATION
What happens at the venous end of a capillary in terms of fluid forces? - ANS capillary
oncotic pressure > interstitial hydrostatic pressure = fluid back into ciruclation
REABSORPTION
What is the pathophysiology of edema? - ANS increased in forces favoring fluid filtration
from the capillaries or lymphatic channels into the tissues
What is the primary ECF cation? - ANS Sodium
What is the primary ECF anion? - ANS Chloride
Describe the relationship btw. Chloride and sodium and bicarbonate - ANS Cl follow sodium
and varies inversely with bicarb.
What hormone regulates sodium? where is it synthesized? - ANS Aldosterone. Synthesized in
the adrenal cortex.
When is aldosterone secreted? - ANS Decreased renal perfusion, low NA levels, high K levels.
What are the effects of aldosterone secretion? - ANS Acts on the distule tubule of the kidney
to reabsorb sodium and water and excrete K and H+ into urine.
Describe the renin-angiotensin-aldosterone system - ANS decreased blood pressure causes
the juxtaglomerular cells of kidney to secrete renin
renin stimulates angiotensin I
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