14 - pH and Buffers PPT (QUIZ 4) Flashcards
What pH does the body work best at?
7.4 pH
When the pH drops below 7.4, what is this called?
Acidemia
When the pH rises above 7.4, what is this called?
Alkalemia
What are buffers?
A weak acid with its conjugate base form OR a weak base with its conjugate acid from
What’s one of the most important buffers in the body?
H2CO3 (weak acid) and HCO3- (BICARB)
What are H2CO3 and bicarb apart of?
The blood buffer system
As a weak acid, H2CO3 (carbonic acid) easily dissociates into ____________ ions and ____________ ions.
- hydrogen
- bicarbonate
When there’s few hydrogen ions around, carbonic acid becomes…
… hydrogen and bicarb
When there’s lots of H+ ions around, ____________ will bind to one and form ______________ acid, which then splits into ______ and ______, which we then breathe out through the lungs.
- bicarbonate
- carbonic
- H2O
- CO2
What are the other two buffer systems?
- Phosphate buffer
- Protein buffer (such as albumin)
What are the two ways our kidneys maintain acid-base balance?
- They reabsorb bicarb from the urine back into the blood (gross)
- They secrete H+ ions into the urine
What is the first step the kidney takes to begin acid-base balancing?
It reabsorbs bicarbonate
What snatches up bicarb and sodium on the basolateral surface (aka tubular lumen)?
A sodium/bicarbonate cotransporter
What exchanges bicarb for chloride when leaving the bloodstream to enter cells? (You’ll never guess)
The bicarb/chloride exchanger lol
What is one mechanism that gets H+ ions into the urine since they can’t do it themselves?
The sodium/hydrogen countertransport in the PCT
How does the sodium/hydrogen countertransport work?
A carrier protein in the apical wall binds a H+ ion from the cell and a Na+ ion in the tubular fluid
Why can’t the urine hold on to more free H+ ions?
Because Owen, the pH would drop way too low, and it would BURN UP THE TUBULES because they can’t maintain a urine pH of less than 4.5!!!
What’s the safeguard for preventing such a catastrophic event of melting the tubules?
There’s chemical buffers in urine that bind H+ ions and keep the pH from going too low!
What’s THE MOST IMPORTANTE system in the body?
The ammonia buffer system
What’s the process called that the kidneys use in ammonia buffer?
Ammoniagenesis
Ammonia is ________ soluable.
lipid
(TRUE/FALSE): Ammonium chloride is highly acidic.
(FALSE): It is weakly acidic and won’t really alter the urine pH.
What helps the kidneys purge a large amount of H+ ions?
Binding the H+ ions to ammonia to make ammonium (NH4+), because NH4+ gets kicked out quick through the urine
How does the second buffer system utilize phosphate?
It combines phosphate with secreted H+ ions to form dihydrogen phosphate (H2PO4), which gets SHOT OUT in URINE!
