Chapter 2: Additional Slides Flashcards
first line of defense against pH shift
chemical buffer system
second line of defense against pH shift
physiological buffers
chemical buffer systems
- bicarbonate buffer system
- phosphate buffer system
- protein buffer system
physiological buffers
- respiratory mechanism
- renal mechanism
respiratory mechanism
CO2 excretion
renal mechanism
H+ excretion
bicarbonate buffer maintain a __:__ ratio of bicarbonate to carbonic acid
20:1
bicarbonate
HCO3-
carbonic acid
H2CO3
what do lung eliminate
carbon dioxide
what can kidneys remove
excess non-gas acids and bases
enzyme that assists rapid inter-conversion of carbon dioxide and water into carbonic acid, protons and bicarbonate ions
Carbonic anhydrase
where are carbonic anhydrase found
- red blood cells
- gastric mucosa
- pancreatic cells
- renal tubules
to lower pH, kidneys excrete
HCO3-
to raise pH, kidneys excrete __ and lungs excrete __
- H+
- CO2
sodium bicarbonate
NaHCO3
when can carbonic acid buffer system only function
respiratory system and respiratory control centers are working normally
ability to buffer acids is limited by what?
availability of bicarbonate ions
what is the pKa of carbonic acid
6.35
pH of blood
7.4
has a much larger capacity of resisting change in pH
more concentrated buffer
major buffer system of the body
bicarbonate buffer
very effective but not found in high concentrations in extracellular fluid
phosphate buffer
where is the phosphate buffer important
- intracellular fluid (ICF)
- renal tubules
optimum pH of phosphate
6.8
What are the two types protein buffers
- amino acids
- hemoglobin
respond to pH changes by accepting or releasing H+
free and terminal amino acids
amino acids:
if acid comes into blood, hydronium ions can be neutralized by what group
-COO-
amino acids:
if base is added, it can be neutralized by what group
-NH3+
- binds CO2
- binds and transports hydrogen and oxygen
- maintains blood pH as it changes from oxyhemoglobin to deoxyhemoglobin
hemoglobin
hemoglobin maintains pH as it changes from what to what?
- oxyhemoglobin
- deoxyhemoglobin
- exhalation of CO2
- only works in volatile acids
- does not affect fixed acids
- pH can be adjusted by changing rate and depth of breathing
- provide O2 to cells and remove CO2
respiratory regulation
respiratory regulation only works on what acids
volatile acids
respiratory regulation equation
CO2 + H2O <-> H2CO3 <-> H+ + HCO3-
- drives reaction to the left
- caused removal of H+
- pH goes up
hyperventilation
- drives reaction to the right
- additional of H+
- pH goes down
hypoventilation
- can eliminate large amounts of fixed acid
- excrete base
- conserve and produce bicarbonate ions
renal regulation
renal regulation is the __ __ regulator of pH
most effective
primary base in the body
HCO3
for every hydrogen ion buffered by bicarbonate - a __ __ is consumed
bicarbonate ion
where is the bicarbonate freely filtered
glomerulus
approx. how many bicarbonate would be filtered in 24 hours
4300mmol
what happens when re-generation of bicarbonate would not happen
cause acidotic state
Renal Bicarbonate Regeneration involves what enzyme
carbonate dehydratase (carbonic anhydrase)
catalyses the formation of CO2 and H2O from carbonic acid (H2CO3) in the renal tubular lumen
carbonate dehydratase
CO2 diffuses across the __ __ into the __ __
- luminal membrane
- tubular cells
renal response to acidosis
- increased reabsorption of filtered HCO3-
- increases excretion of titratable acids
- increased production of ammonia
titratable acids excreted in urine during acidosis
H2PO4- (Dihydrogen phosphate)
principal source of NH3 production in the kidneys
deamination of glutamine
when body is in alkalosis, tubular cells secrete __ __ and reclaim __ __
- bicarbonate ions
- hydrogen ions
the amount of strong base needed to titrate the urine pH back to 7.4.
Titratable acid (TA)
