Renal physiology 3 Flashcards
1
Q
What are the main functions of the kidney?
A
Endocrine functions: cortisol, aldosterone, erythropoetin ( hypoxia) Removal of waste products e.g urea electrolyte balance gluconeogenesis regulate body fluids: ph/osmolarity
2
Q
What are the main functions of calictriol?
A
Active form of Vitamin D released when [Ca2+] = low
- Increased bone resorption
- Increases gut absorption
- Increases renal Ca2+ reabsorption
- Decreases PTH
3
Q
What are the main functions of PTH?
A
- Increases Ca2+ rebabsorption ( upregulation of TRPV5 channels)
- Decreases Pi ( internalisation of pi transporters)
- Increases bone resorption
4
Q
How is Ca2+ reabsorbed?
A
Paracellular transport : solvent drag ( follows Na+)+ transepithelial voltage ( more negative lumen potential allows for secretion/excretion)
- Ca2+ enters epithelial cells via TRP5V channels
- Ca2+ binds to calbidin = buffer
- Transported to the basolateral membrane
- ATPase channels (basolateral membrane) allow exchange for 1 Na+ into the cell for 1 Ca2+ out
5
Q
How does hypertension worsen kidney damage?
A
- Kidney damage causes GFR to decrease
- Macula densa cells detect a decreased filtered load of Na+ Cl-
- Signal sent via adenosine and Ca2+ to increase GFR by vasodilation of afferent arteriole and vasoconstriction of efferent arteriole
- Renin secretion from granular cells -> RAS system activation
- Hypertension increases glomerular pressure so there is further kidney damage
Treated with ACE inhibitors e.g ramipril
6
Q
Describe diabetic nephropathy
A
- Poorly controlled diabetes causes more overspill of glucose into the urine
- More glucose in glomerular capillaries and bowmans space
- glucose reabsorbed in the PCT along with Na+
- More Na+Cl- reabsorbed along with water
- Macula densa cells detect a decreased filtered load of Na+Cl-
- Tubuloglomerular feedback causes vasodilation of afferent arteriole and vasoconstriction of the efferent arteriole to increase GFR and pressure in the glomerular capillaries
- Activates matrix deposition + Hypetrophy + proliferation of mesangial cells which form sclerosis
- Compresses the glomerular capillaries + decreases GFR = kidney damage