Renal Phys--> acid/base Flashcards
What are the 3 fundamental components of the acid base system?
- acid
- base
- H+ (+) conjugate base
what is normal pH? What is the H+ nanaomoles?
- 35-7.45
- around 40 nanaomoles of free hydrogen
- gut has about 100 mM
What is the equation of pH?
pH=pK+log[base/acid]
What is acidemia and alkemia?
Increase or decrease in H+ but tells us nothing about cause
What is acidosis and alkalosis?
the description either metabolic or respiratory which leads to acidemia and alkemia
What are the physiologic buffers?
Bicarb Hgb Po4- Albumin Bone
What are some common chronic effects of chronic acidosis? What for?
Osteopenia and osteoporosis
- seeking bicarb
What is the Henderson-Hasselbalch equation?
7.4= pH=6.10+log [HCo3}/(0.03*Pco2)
What is the Kassier-Bleich equation?
H+=24(PCo2)/[HCo3-]
- where H+ is in nanamoles/liter
What is the average change in nanomoles for 0.1 change in pH?
about 10nEq/L
40=7.4
50=7.3
60=7.2
What are the classic physiologic responses to acidosis?
- Increase respiration
- Kussmal breathing: deep, slow and labored
- Depressed cardiac contractility
- Increases circulating catecholamines
- Stimulates protein catabolism leading to negative nitrogren balance
- Leads to bone loss (need Hc03- from bones)
What are the physiologic responses to alkalosis?
- Hypoventalation
- Cardiac arrhythmias
- Shifts O2 dissociation curve to LEFT, decreasing delivery to tissues
- Increased lactate
What are the 2 primary dietary sources for Acids?
Carbonic acids
Non-carbonic acids
Where do carbonic acids come from?
Volatile acids
- Metabolism of carbs of fats
What do carbonic acids break down into and where are they excreted?
into CO2 and Water
- lungs
Where do non-carbonic acids come from?
Metabolism of proteins
- Generally sulfur containing AA or hydrochloric acid
Where are non-carbonic acids excreted?
Kidneys
- about 50-100mEq/day
Where is another place can create acids?
GI tract
- in exchange for Hco3-
How do we manage acid load?
Buffering
Renal excretion
How is acid/base homeostasis disrupted?
Either addition of H+
or Loss of HCo3
What is the role of the kidneys in the acid/base homeostasis?
Basically everything
- reclaim HCo3- (we have lost some to H+ buffering we don’t want to loose anymore in the urine)
- Excrete excess acid
how doe we replace the bicarb deficit?
Reclaim It
- must be free and not bond to H+ otherwise you are absorbing neutral contents that is useless for acid/base homeostasis
- use non-bicarbonate
What are 2 ways to get non-bicarb bases into the renal lumen?
Filter them
Make them
What happens in the proximal tubule to reclaim bicarb?
- reclaim the bicarb
2. create ammonium (carrier of H+)
What increases the H+ and Na+ antiporter?
AgII
Sympathetics
Decrease in pH
Increase in Co2
What increases glutaminase? What is this used for?
Increase H+
Decreased pH
- used to breakdown glutamine into alpha-ketobutyrate and NH4+
Why is glutaminase important?
Makes NH4+
- Which carries a H+ out
- more acidic the lumen the less likely it is to dissociate to NH3 and H+
What percent of H + is handles by phosphorus and what is handled by Ammonium?
1/3 Phosphorus q
2/3 NH4+
Which cell the Beta or alpha intercalated secrete H+ and which absorbs it?
Alpha secretes it and absorbed HCo3-
Beta secretes it and absorbs H+
Increase or decrease in HCo3- leads to Alkalosis? Which type?
Increase
Metabolic
Increase or decrease in HCo3- leads to acidosis? Which type?
Decrease
Metabolic
Increase or decrease in PCo2 leads to Alkalosis? Which type?
Decrease
Respiratory
Increase or decrease in PCo2 leads to acidosis? Which type?
Increase
Respiratory
What organ compensates for respiratory issues? Metabolic?
Kidneys- matter of days
Lungs- matter of minutes
What is the bicarb and pH in respiratory acidosis? Cause
Increased Decreased - Lack of ventilation - Morphine, succ, GHB, heroin - PE, obstruction and COPD
What is the bicarb and pH in respiratory alkalosis?
Decreased
Increased
- Too much breathing, Panic attacks, high altitude
What is the bicarb and pH in Metabolic acidosis?
Decrease
Decrease
- HCo3= D, fistulas, urinary diversion
- H= Lactate, ketones, RF, aspirin toxicity, methanol, ethylene glycol
What is the bicarb and pH in metabolic alkalosis?
increase
increase
- either increase in bicarb or loss of H+
- First is usually renal excretion impairment and volume depletion
- 2nd is usually due to vomiting and NG suction
What does increase H+ lead to in the kidney?
unregulates:
- Glutaminase
- Carbonic anhydrase
- Na/H anti-porter
Does hyperkalemia or hypo lead to increase in NH3 production?
Hypo
what is hyperkale renal tubular acidosis?
Hyperkale leads to decrease in NH3 production which is used for a H+ carrier. Decreasing NH3 leads to decrease in H+ secretion!
