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Most water in the body is in the _______
- cytosol (ICF)
- -it's intracellular
99% of ECF is ________
Why does the body need water?
- Enzymatic reactions
- maintain normal volume/composition of ICF/ECF
- (isotonic environment)
how do we gain water?
- byproduct of metabolism
How do we lose water?
Primary source of water gain?
- Gain: digestive system
- Loss: urinary system
What are the most important electrolytes for maintaining electrolyte balance, and why is that?
- Sodium, then chlorine (Cl-)
- Cl- follows Na+ (charge)
- H20 follows Na+
What are electrolytes?
ions released through dissociation of inorganic compounds
why do we need electrolytes?
- can conduct electrical current in solution
- excitable membranes
most common cation in ECF
most common cation in ICF
Most common anion in ECF
chlorine, then bicarbonate
most common anions in ICF
phosphates and proteins
what does our body tend to generate? what does the body do about it?
water accounts for what percentage of male body weight?
- Male 60%
- Female 50%
- Newborn 75%
- Elderly/obese 45%
why do we lose water with age?
- muscle holds water
- loss of muscle -> loss of water
what in our body holds a lot of our water? What doesn't?
- muscle does
- fat doesn't (hydrophobic)
what are the two major subdivisions of the ECF? Which is most abundant?
- ICF and blood plasma
- ICF most abundant
Minor subdivisions of ECF
- Synovial fluid
- serous fluids
- aqueous humor
what do the kidneys do to maintain acid/base balance?
secrete H+ into urine, generate buffers that enter bloodstream
What's the main solid that makes up the body?
- behave as distinct entities
inside of cell is slightly _____, outside slightly ______
describe the difference between the osmotic concentration of the ICF and the ECF
always striving to be equal (isotonic)
if one becomes more concentrated, water will move via osmosis until they are equal again
hormones regulating electrolyte balance and how (4)
- adh : water
- aldosterone: sodium, potassium, chlorine
- anp/bnp: antagonistic
- angiotensin II: reabsorbs sodium, secrete hydrogen
adh target and function
- collecting duct
- inserts aquaporins
- stimulates thirst center
what monitors the osmotic concentration of ECF? what does this prompt?
- osmoreceptors in the hypothalamus
- -location of BBB
- causes secretion of ADH and angiotensin II
- stimulates thirst center
if you are sweating, is your ECF hyper or hypo tonic?
If you drink a lot of pure water, what happens to your ECF?
what stimulates the release of aldosterone?
- concentrated ECF (hypertonic)
- rising potassium levels: hyperpolaria
What disease targets adrenal glands, inhibiting production of aldosterone? what are the results of this disease?
- Addison's disease
- chronic low blood pressure
when body loses water, plasma volume increases/decreases? electrolyte levels rise/fall? when does this occur?
- during exercise
what force pushes water out of plasma and into the ICF?
net hydrostatic pressure
what force draws water out of ICF and into plasma?
Net colloid osmotic pressure
edema occurs when there is excess fluid in the ____
why do you lose more water via respiration on cold days?
rapid water movements between ECF and ICF
severe water loss
what happens when water is gained but electrolytes aren't?
ECF volume increases, becomes hypotonic to ICF, fluid shifts to ICF, cells swell up and aren't as excitable
excessive production of what hormone can lead to overhydration?
what disorders/diseases may cause overhydration?
- chronic renal failure: glomeruonephritis
- heart failure -> edema
- cirrhosis: lowers BCOP -> excess filtration, not enough reabsorption
- all lead to inability to remove water in urine