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
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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
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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
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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
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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
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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
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