increases sodium premeability of plasam membranes, over exciteable nervouse/muscluar systems
causes: tetany
describe the imporatance of maintainig the pH of body fluids:
essential for protein fxn
metabolism
fxn of enzymes
describe acids, bases, and buffers:
acidschemcials that release H+
strong: HCl = H+ (+) Cl-
weak: H2CO3 = H+ (+) HCO3-
baseschemicals that accept H+
strong: OH- (+) H+ = H2O
weak: HCO3-
buffers
stablilze pH
remove or add H+ to solutions
coverts strong acid or base to a weak one
H2CO3 <--> H+ (+) HCO3-
define buffer systems and list the major buffer systems of the intracellular and extracellular fluids:
buffer systems: composed of weak acids and weak bases
ECF
bicarbonate buffer system: solution of carbonic acid and bicarbonate ions
CO2 + H2O <--> H2CO3 <--> HCO3- (+) H+
ICF
phosphate buffer systems: a solution of HPO4(2)- and H2PO4-
H2PO4- <---> HPO4(2)- + H+
important in renal tubules and ICF
protein buffer systems: some amino acids have carboxyl (-COOH) groups which release H+, others have an amino (-NH2) group, which binds to H+ when pH falls
3/4 of chemical buffering in body fluids
HgB and plasma proteins
identify the sources of hydrogen ion gain and loss:
H+ gain increased CO2 (hypoventilation)
decreased HCO3- metabolism (diarrhea, urine)
H+ loss increased CO2 (hyperventilation)
decreased H+ metabolis, due to high protein in diet, excess H+, urine acidic (vomit, urine)
describe the role of buffer systems, the respiratory system, and the urinary system in maintaining acid-base balance:
stabalize pH
buffers 1st mechanism
fast, msec - sec.
least buffering capacity
respiratory 2nd in terms of speed
sec. - min.
via CO2 levels
middle level buffering capacity
urianry (renal) 3rd in speed
slow
hours- days
via HCO3-/H+ levels
most buffering capacity
describe the mechanisms by which the kidneys control blood pH:
when pH is balanced
HCO3- filtered, but cant be directly reabsorbed
filtered HCO3- recylced into new HCO3-
all filtered HCO3- recovered, no net gain or loss
H2O + CO2 > H2CO3 > HCO3- (goes into interstitial fluid), H+ goes into tubular fluid, combinds with HCO3- > H2CO3, then dissoicates into H2O and CO2, water is excreted and CO2 goes back into the tubular cells and begins rxn again
normal pH: all filtered HCO3- is recovered
excess H+
typcial: when all HCO3- is gone from tubular fluid, secreteds H+ combinds with HPO4(2)- * phosphate buffer*
H2O + CO2 > H2CO3 > H+ into tubular fluid, combindes with HPO4(2)- > H2PO4-, excreted, gets rid of extra H+
HCO3- is recovered in interstitial fluid
interstitial fluid impacts: HCO3- recovered, net HCO3- gain, net H+ loss, neurtralize acid
excess H+ is greater w/ amino acid catabolism, H+ secreted + excreted as NH4+
glutamine: breaks down into HCO3- recovered in interstitial fluid, NH4+ (antiports with Na+)
acidosis pH < 7.35
all filtered HCO3- is recovered and extra H+ is secreted
excreted: binds to phosphates, as NH4+
alkalosis pH > 7.45
not all filtered HCO3- is recovered, so HCO3- is excreted
define acidosis:
a pH below 7.35
increased acidity
increased H+
decreased pH
define alkalosis:
a pH above 7.45
increased alkalinity
decreased H+
increased pH
distinguish beteween respiratory and metabolic acid-base imbalances:
respiratorypH changes by respiratory system
renal system compensates (change in CO2)
if possible, respiratory system helps correct
metabolicpH cnages not caused by changes in CO2
respiration system compenstates, if possible
renal system helps correct
describe the problem, cause, repriratory compenstation, and renal compensation for respiratory acidosis:
problem: increased CO2, increased H+
cause: hypoventilation, emphysema
respiratory comp: increased ventilation, decrease CO2
renal comp: increased H+ excretion
describe the problem, cause, repriratory compenstation, and renal compensation for respiratory alkalosis:
problem: decreased CO2, decreased H+
cause: hyperventilation, high altitude
respiratory comp: decreased ventilation, increase CO2
renal comp: increased HCO3-
describe the problem, cause, repriratory compenstation, and renal compensation for metabolic acidosis:
problem: increased H+ or decreased HCO3-
cause: excercise, diabetes, chronic diarrhea
respiratory comp: increased ventilation, decreased CO2
renal comp: increased H+ excretion
describe the problem, cause, repriratory compenstation, and renal compensation for metabolic alkalosis:
problem: decreased H+, or increased HCO3-
causes: vomiting
respiratory comp: decreased ventilation, increased CO2
renal comp: increased HCO3-
define hyperkalemia:
K+ > 5.5 mEq/L
less concentration difference between the ICF and ECF, so outward diffusion is reduced (increased K+ in ECF)
more K+ remains inside the cell
plasma membrane has a less negative resting potenitial, closer to the threshold at which it will set off action potenial (more depolarized)
Dehydration can lead to an increase in [Na+] in the blood. Place the following events in the correct sequence for countering this physiological problem.
aquaporins inserted into the collecting duct
osmoreceptors stimulated
blood osmolarity decreases
elevated blood osmolarity
release of ADH
increased water reabsorption
