L13: Acid Base Regulation Flashcards
What happens in renal failure to the acid base regulation
Patients become acidic
How is ph normally maintained by in the kidney
By bicarbonate which buffers in the kidney
When is hydrogen ion produced
ATP is hydrolysed
During anaerobic respiration with production of lactate
During production of ketones in diabetes mellitus
During ingestion of acids
How does hydrogen ions become removed
By reacting with hco3- iosn
What does the reaction of hco3- and h+ ions result in
Carbon dioxide and water
How is hco3- replaced when it is lost through the production of water and co2
Hco3- becomes reabsorbed in the kidney
Which part of the nephron reabsorbs hco3-
The proximal tubule
Describe the involvement of channels in the proximal tubule
1) Sodium and hydrogen exchanger brings in sodium and removes hydrogen ions
2) hydrogen ions within the filtrate react with hco3- to form water and carbon dioxide
3) water and carbon dioxide diffuse into the cells and dissociate back into hydrogen ions and hco3-
4) bicarbonate ions leave into the cortical interstitial space by the 3hco3-/na+ cotransporter in the basolateral membrane
Do we absorbs hco3- when it is excess
No it is lost in the filtrate
Why is hco3- lost in the filtrate when it is excess
Because the sodium/bicarbonate cotransporter can only work at a certain rate therefore is becomes rate limited and lost in the filtrate
If lots of hco3- is lost in the filtrate how do we replace this
By producing it
Where is bicarbonate produced
In the proximal tubule
When is hco3- made
When carbon dioxide enters the cells in the proximal tubule from the vasa recta
What is the vasa recta
The blood vessels that surround the loop of henle
Describe how the production of hco3- occurs
1) carbon dioxide enters the cells in the proximal tubule from the vasa recta
2) carbon dioxide and water react to form h2co3 via carbonic anhydrase
3) h2co3 dissociates to form hydrogen and bicarbonate ions
4) hydrogen leaves into the filtrate by the sodium/hydrogen exchanger
5) bicarbonate leaves into the cortical interstitial space through the basolateral membrane by the sodium/bicarbonate cotransporter
What are the other wats of regulating hydrogen ions
Secreting them in the distal tubule
How is hydrogen ions secreted in the distal tubule
By the:
Hydrogen/pottasium ATPase
Hydrogen ATPase
Where is phosphate present
In the circulation
Does phosphate become filtered into the filtrate
Yes
If phosphate becomes filtered what can it do to hydrogen ions
Buffer it
What happens to phosphate when it reacts with hydrogen ions
Becomes
HPO4^2-
H2PO4-
H3PO4
What are the common forms of phosphate fond in the urine and plasma when it reacts with hydrogen
HPO4^2-
H2PO4-
Which is the most common form of phosphate and hydrogen in the urine
H2PO4-
How is ammonium ions produced
By the conversion of glutamine to glutamic acid
