chapter 27 Flashcards
fluid
- definition
- 2 types
- water
- extracellular fluid
- intracellular fluid
- extracellular fluid
extracellular fluid
blood plasma, interstitial fluid, other
intracellular fluid
cytosol (within cells)
eletrolyte
- definition
- most important
inorganic compounds that dissociate in solution to form ions
-sodium
electrolyte: sodium
- most abundant where
- function
- in the CSF
- main contributor to osmolarity of blood
2 factors that must be controlled
- fluid balance
2. electrolyte balance
fluid balance
- water gained=
- normal blood vol
- water lost
- ~5 L
electrolyte balance
- electrolytes in =
- normal blood osmolarity
- electrolytes out
- 300 mOsm/L
how do you gain water?
-lose?
- food, beverage and metabolism
- urine, feces, sweat and breathing
application: suppose you eat an extra large jumbo tub of movie popcorn with extra salt and butter
- blood osmolarity will
- blood vol will
- how does the body detect these changes?
- increase
- not change
- osmoreceptors in hypothalamus will sense an increase in blood osmolarity (sense of an increase in the concentration of Na+ of blood)
application: suppose you eat an extra large jumbo tub of movie popcorn with extra salt and butter
- how does the body respond to these changes?
- effect
- increasing secretion of antidiuretic hormone
- decrease secretion of aldosterone
- restore osmolarity of blood by increasing retention of H2O and decreasing reabsorption of sodium; kidneys produce small vol of concentrated urine
increasing secretion of antidiuretic hormone effects
- increase thirst (consume liquids)
2. decrease water loss at kidneys
decreasing secretion of aldosterone effects
decreases Na+ reabsorption in kidney
application: suppose you drink a very large volume of water
- blood osmolarity will
- blood volume will
- how does the body detect these changes
- decrease
- increase
- osmoreceptors detect a decrease in the concentration of Na+ of the blood
application: suppose you drink a very large volume of water
- how does the body respond to these changes?
- secretion of ADH will decrease
- secretion of aldosterone will increase
- kidneys produce a large vol of dilute urine
decreasing secretion of ADH efects
- decreases water reabsorption in DCT and CD
- decreases thirst
increasing secretion of aldosterone effects
increases sodium reabsorption
application: suppose you consume a large vol of an isotonic solution
- blood osmolarity will
- blood vol will
- how does the body detect these changes
- not change
- increase
- baroreceptors will detect an increase in BP because of an increase in blood vol
application: suppose you consume a large vol of an isotonic solution
- how does the body respond to these changes
secretion of atrial natriuretic peptide will increase
increasing secretion of ANP causes
-effects
- ADH secretion to decrease
- aldosterone secretion to decrease
- kidneys will produce increased vol of urine with and increased Na+ content
application: suppose you are in a very severe car accident and are suffering from excessive blood loss
- blood osmolarity will
- blood vol will
- how does the body detect these changes
- not change
- decrease
- as blood vol decreases, BP declines
application: suppose you are in a very severe car accident and are suffering from excessive blood loss
- how does the body respond to these changes?
- increase in ADH release
- increase renin secretion
- both work to return blood vol and pressure to normal
increasing renin secretion =
increase in angiotensin II activation
angiotensin II activation
-3
- increases aldosterone release which increase Na+ retention in the kidneys because water follows salt and water will be retained
- causes vasocontriction = increased BP
- promotes release of ADH
pH
- definition
- formula
- pH of extracellular fluids
- concentration of H+ ions in a solution
- [H+] = 1 x 10 ^ -7 M –> pH = 7
- 7.35 - 7.45
2 conditions of pH
- acidosis
- alkalosis
- primarily effects CNS and cardiovascular functions
acidosis
- pH
- serious?
- below 7.35
- very serious problem
alkalosis
- pH
- serious?
- above 7.45
- serious but not as common
why is the maintenance of pH a problem?
- H+ gains=
- constantly producing H+ through
- formula
- H+ must be
- H+ loses
- metabolic activities
- Co2 + H2O H+ + HCO3-
- eliminated or “tied up” to maintain pH
3 mechanisms of acid-base balance
- buffer system
- respiratory system
- urinary system
buffer system
- buffer
- 3 major systems
- compound that stabilizes the pH of a solution by providing or removing H+ ions
- protein buffer system
- carbonic acid-bicarbonate buffer system
- phosphate buffer system
- protein buffer system
protein buffer system
- definition
- type of protein
- AA accepts or releases H+ ions
- hemoglobin
how does hemoglobin play a role in the protein buffer system?
by maintaining pH as pCo2 changes
carbonic acid-bicarbonate buffer system
- formula
- function
- what happens when equation shifts to the left
- Co2 + H2O (H2Co3) H+ + HCO3-
- can prevent changes in pH after addition of H+ ions
- Co2 is released in lungs
phosphate buffer system
- equation
- function
- H2Po4- H+ + HPo4 ^2-
- plays a supporting role in maintaining pH
respiratory system
- what do changes in respiratory rate do
- direct effect on
- equation
- stabilizes pH of ECF
- direct effect on carbonic acid/bicarbonate buffer system
- Co2 + H2O H+ + HCO3-
respiratory system
- increase in pCo2 =
- decrease in pCo2=
- decrease in pH = increase in respiratory rate = more Co2 lost at lungs = pCo2 and pH returns to normal
- increase in pH= decrease respiratory rate = less Co2 lost at lungs = pCo2 and pH returns to normal
urinary system
- definition
- occurs where
- principle of buffering system
- changing the rate of H+ and HCO3- secretion or reabsorption by the kidneys regulates the pH of the ECF
- along the PCT, DCT and CD
- Co2 + H2O (H2CO3) H+ _ HCO3-
urinary system
- where does the Co2 come from
- principle of buffering system relies on
- decrease pH of ECF
- increase pH of ECF
- from tubular fluid, blood and tubular cells
- relies on carbonic anhydrase in tubular cells
- H+ is secreted into tubular fluid and HCO3- is released into blood = increase in pH of ECF in blood
- HCO3- is secreted into tubular fluid and rate of H+ secretion declines = decrease in pH of ECF
