Fluid Flashcards
effects on fluid balance
age, muscle, body fat, sex
how does age affect fluid balance
lose fluid as we age
how does muscle affect fluid balance
more muscle = more fluid retention
fluid retention increases as body mass increases, esp muscle mass
how does body fat affect fluid balance
more adipose tissue causes less fluid retention
how does sex affect fluid balance
men retain more fluid than womn
testosterone (M) causes more muscle –> more fluid
estrogen (F) causes more adipose –> less fluid
fluid compartments
intracellular
extracellular
body is ____% water
50-60
intracellular fluid compartment
2/3 of body fluid is in cytosol of cells
extracellular fluid compartments
1/3 of fluid in interstitial space or blood volume (mostly interstitial space)
fluid in interstitial space is interstitial fluid; fluid in blood is plasma
fluid composition
water
nonelectrolytes
electrolytes
why does water need to be in fluid
it makes things biologically active
nonelectrolytes
organic molecules (do not associate in water) can cause osmotic gradients
electrolytes
ions (inorganic salts, acids, bases, proteins)
dissociate in water
much stronger osmotic power than nonelectrolytes
composition of electrolytes
varies in different body parts sodium (mostly outside cells) potassium (mostly inside cells) bicarbonate (buffer mostly outside cells) phosphate (buffer inside cell)
if high electrolyte concentration inside cell, then low electrolyte concentration outside cell except…
except proteins
bc we cannot filter out blood proteins
2 types of fluid movement
between plasma and interstitial fluid
between interstitial fluid and intracellular fluid
fluid movement between plasma and interstitial fluid
out of blood into interstitial fluid
most escape and come back in
bp regulates this
major factor of fluid movement between interstitial fluid and intracellular fluid
osmotic gradient across selectively permeable membrane
2 factors that regulate fluid movement
osmotic gradients (ionic concentrations) hydrostatic pressures (high to low pressure)
what factor is more important for intracellular fluid movement
osmotic gradients
what factor is more important for plasma movement
hydrostatic pressures
ways to intake water
ingestion
metabolic water
metabolic water
oxidation/cell respiration makes H2O
doesn’t produce enough to live
ways to output water
vaporization (exhale; insensible water loss)
perspiration (sweat; sensible water loss)
elimination
urination
vomiting
regulation mechanisms for water input/output
- increase in plasma osmolality or decrease in blood volume promotes thirst
- decrease in extracellular fluid osmolality (diluted blood) decreases ADH absorption and causes us to reabsorb less water
- large decrease in bp increases ADH production
how is thirst promoted?
increase in plasma osmolality (blood getting more concentrated) or decrease in blood volume
increase in plasma osmolality is detected by chemoreceptors which send signal to brain
decreased blood volume decreases bp which is detected by baroreceptors
how does decrease in extracellular fluid osmolality affect things?
it causes decreased ADH absorption so we do not reabsorb as much water
ADH isn’t absorbed so aquaporins stay closed and filtrate concentration decreases
how is ADH production affected by large decrease in bp
increases ADH
so we absorb more water and increase bp
how to intake electrolyes
ingestion
metabolic production
metabolic production of electrolytes
when we break things down (esp nucleic acids)
nucleic acid metabolism produces salts
how do we output electrolytes
perspiration
elimination
urination
vomiting
what is sodium most important for
creating osmotic gradients
where is sodium concentration greatest
extracellular fluid compartments
sodium regulation
linked to bp and blood volume (monitored by baroreceptors)
no chemoreceptors monitoring Na concentration
90% Na absorbed naturally
6 factors/mechanisms of Na regulation
aldosterone cardiovascular baroreceptors ANP estrogen progesterone glucocorticoids
Aldosterone mechanism of Na regulation
major regulator of Na
increased aldosterone –> increased sodium absorption –> decreased urinary output
ADH can increase aldosterone’s effect
most active in ascending limb of loop of henle
MD cells sense change in solute concentration of fluid in DCT –> activate JG cells –> secrete renin
H2O follows Na –> increased blood volume, increased bp –> shuts off renin and aldosterone
t/f ADH can decrease effects of aldosterone
false!
ADH increases effects of aldosterone
where is aldosterone produced
zona glomerulosa of adrenal cortex
cardiovascular baroreceptor mechanism of sodium regulation
cardiovascular baroreceptors detect changes in bp near heart
increase in bp –> decrease in sympathetic stimulation of kidney –> afferent arteriole dilates –> increased gfr –> increased Na output –> increased urinary output –> decreased blood vol, decreased bp
feedback mechanism to regulate bp
ANP mechanism of Na regulation
produced by heart when bp is high
stretch of heart wall triggers production
causes vasodilation, incr. filtration, decr. ADH (aquaporins close), decr. renin, decr. aldosterone
estrogen mechanism of Na regulation
increases Na absorption
progesterone mechanism of Na regulation
decreases Na absorption
glucocorticoids mechanism of Na regulation
increases Na absorption
synergists for aldosterone
blood pH
7.35-7.4
pH of intracellular fluid
~7
due to CO2
why does body need to maintain neutral pH
for catalyst functioning
sources of H+
dietary, metabolic
acidosis
too acidic
alkalosis
too basic (high pH)
respiratory acid/base alterations
caused by change in rate of breathing function of CO2
respiratory acidosis
decreased gas exchange, slowed breathing
causes CO2 accumulation in blood
respiratory alkalosis
hyperventilation
causes loss of a lot of CO2
metabolic acid/base conditions
abnormalities for reason other than CO2
metabolic alkalosis
vomiting promotes alkalosis
t/f alkalosis promotes vomiitng
true
systems of acid-base regulation
chemical buffer systems
physiological buffer systems
renal mechanisms
chemical buffer systems
temporary mechanism
proton donors or acceptors (temporary binding)
bicarbonate, phosphate, or proteins
bicarbonate chemical buffer system
important in extracellular fluid coompartment
more outside than inside
buffers by donating or accepting H+
phosphate buffer system
most active inside cell
accept or liberate H+ ions
protein chemical buffer system
act as amphoteric molecules
proteins can be found in intracellular or extracellular compartments (this is why it is most important)
only temporary
physiological buffer systems
change in respiratory gas exchange (change in breathing rate) to retain or lose CO2
only works with CO2
slower, but 2x more Power of all chemical buffer systems combined
changes blood pH and changes breathing rate
___ in blood pH is correlated with ___ in breathing rate
increase; decrease
renal mechanisms
eliminate all acids except CO2
permanently change pH of body
3 kinds: reabsorbing bicarbonate, bicarbonate synthesis, bicarbonate excretion
reabsorbing bicarbonate
renal mechanism
bicarbonate reabsorbed out of tubules cells and back into bloodstream
what would have been lost in urine
bicarbonate synthesis
renal mechanism of acid/base regulation
as we excrete acids, acids combine to make bicarbonate
this is producing new bicarbonate in kidneys
bicarbonate excretion
renal mechanism of acid/base regulation
no absorption, extra bicarbonate is moved out into urine for excretion
