Renal Module III Flashcards
What does pH represent?
Concentration of plasma H+
Normal plasma pH?
7.4 (7.35-7.45)
Plasma pH in acidosis?
< 7.35
Plasma pH of alkalosis?
> 7.45
How much H+ is in the blood compared to other plasma ions (Na+, HCO3-, K+, etc.) in a healthy individual?
Small amount when compared to other ions (but critical to maintain plasma pH w/ narrow optimal range):
H+= 0.00004 mEq/L
Na+= 140 mEq/L
HCO3-= 24 mEq/L (22-26 mEq/L)
K+= 3.5-5 mEq/L
What happens to oxygen transport and delivery if plasma pH is not maintained within optimal range?
Impairment of O2 transport/delivery:
-Acidosis: R shift in oxyhemoglobin
-Alkalosis: L shift in oxyhemoglobin
What happens to cell function if plasma pH is not maintained within optimal range?
Disrupted cell function:
-acidosis/alkalosis disrupts structure of cell membrane proteins (ion channels, receptors, etc.) –> impairs cellular & enzyme function in all cells of the body
Death may occur within hours if pH reaches what levels?
Below 6.8 or above 8.0
*loss of cell function/O2 transport leads to system failure (cardio, CNS, pulmonary, renal, liver, etc.) and ultimately death
How is H+ produced from metabolism of proteins (amino acids)?
Body is constantly breaking down cellular/dietary proteins/amino acids to smaller byproducts
*catabolic rxns constantly producing H+ ions
What are protein/amino acid byproducts used for?
Biosynthesis of new proteins/amino acids needed for cell growth/fxn, NTs, NO, etc.
*these rxns recycle a majority of H+ ions preventing/buffers plasma from drastic decrease in pH
How are the remaining protein/amino acid byproducts excreted?
Through the ammonia/urea cycle that influences plasma/urine pH equilibrium
How is glutamine (protein/amino acid) broken down for H+ production?
Broken down into H+ and glutamate (an excitatory NT that plays a central role in regulation of amino acid pH buffering in liver/kidneys)
What happens in the liver during alkalosis?
Converts ammonia to urea which consumes bicarb and produces H+
What happens in the liver during acidosis?
Converts ammonia to glutamine which consumes H+ and produces bicarb
Where does converted glutamine circulate/travel?
Circulates to PCT pof kidney to feed ammoniagenesis-converts glutamine to ammontia and H+ that is secreted into urine
What happens during glycolysis/glucose metabolism?
if O2 not available, glucose is broken down into lactic acid to make ATP –> lactic acid dissociates into lactate and H+ & enter plasma –> lactate & H+ ions circulate to liver where they are recycled back into glucose (Cori cycle)
Does lactic acid contribute to plasma H+ accumulation?
No, except during pathology or extreme exertion
What happens during fat metabolism/ketogenesis?
Fatty acids broken down by liver to acetoacetate which dissociates into B-hydroxybutyrate and H+ / enters the plasma
Where do B-hydroxybutate and H+ circulate to? What happens to them?
Circulate to cells of the body where they will be oxidized/converted back to acetyl CoA & used for energy
Does ketogenesis occur continuously in a healthy individuals?
Yes
Dopes ketogenesis contribute to plasma H+?
No, except when excessive ketogenesis occurs (like in DKA)
How does aerobic metabolism of glucose and fats take place?
if O2 present, glucose and fats (FFA) are broken down/feed TCA/ETC to produce ATP and CO2
*CO2 diffuses into bloodstream, ATP used as energy
Is CO2 in the plasma hydrated?
Yes
What does hydrated CO2 in the plasma form?
Carbonic acid - can dissociate into H+ and bicarb