Fluid&Electrolytes A&P
What is the average water content?
60%, 42 L
How does the avg water content differ in females?
More body fat, less water
What are the fluid compartments?
ICF, ECF
how the percentage of total body water is distributed
plasma
Composition of plasma differ from interstitial fluid?
Wall of capillary separates, proteins higher in plasma ions
How does composition of ECF differ from ICF
ECF more NA, ICF more K
Major cation & anion of ICF
cation- K
anion- phosphates
Major cation & anion of ECF
cation- Na
anion- chloride
What forces water to move between components?
driven by changes in hydrostatic pressure & osmotic pressure
Fluid exchanges in capillary bed
higher hydrostatic pressure than interstitial fluid, pushes fluid out of vessels into interstitial fluid
Tonicity
water moves to where more particles are
Hypertonic/Hypotonic
If an individual takes in water
Plasma dilutes, hypotonic-water moves into cells
If an individual is dehydrated
Plasma is more concentrated, hypertonic-water moves into vessel
Sensible water loss
Noticeable ex. Urine, feces
Insensible water loss
not noticeable, transpiration in skin, lungs
Which type of water loss is most readily controlled to help balance h20 homeostasis?
urine
What ways body gains water?
food, squids, metabolic h2o
Where is thirst center?
hypothalamus
What type of receptor and stimulus
Osmo receptor, Increased osmo
What other stimuli
Decreased plasma volume, decreased saliva, angiotensin 2
What is necessary to form concentrated urine?
ADH countercurrent mechanism to set up osmotic gradient, need juxtamedularry nephrons
Fluid regulating hormone
ADH,
Aldosterone
ANP- looses h2o
Causes of dehydration
Decreased volume
^ Osmo
Low intake
^ output
^ sweat
ADH,aldosterone
Over hydration
^ vol
Decreased osmo
^intake
impaired renal function
abnormal ADH
Volume depletion
Decreased vol
=osmo
loss of h2o & solutes
hemorrhage
severe burns
Volume excess
^vol
=osmo
retention h20 & solutes
vomiting/diarrhea
edema
renal failure
hypoaldosteronism
causes of edema
^capillary pressure
Decrease plasma oncotic pressure
block lymphatics
^ capillary permeable
What are electrolytes
salts that dissociate into ions in solution
What hormones regulate sodium?
Aldosterone says retain Na, Angiotensin 2 retain, ANP loose Na
Hypernatremia
dehydration
Hyponatremia
excessive water and no electrolytes
What hormone regulates K
Aldosterone retain K, loose NA
What other things can influence the distribution of K
Insulin, aldosterone and epic can stimulate movement of K into cells
Hyperkalemia-
renal failure, acidosis
Hypokalemia-
diuretics,
What hormone regulates Calcium (and phosphate)
PTH & calcitrol