GFR review Flashcards
Osmolarity differences
Longer loop of Henle => better at saving water
Osmolarity increases down the loop of Henle - osmotic gradient - essential for movement of water as there are no H2O pumps
glomerulus
The intra-renal baroreceptor is inside the afferent arteriole
Macula densa => if flow is low, GFR is low
What are granular juxtaglomerular cells
Granules => secretory - secreted in response to low BP - beginning of process that gets BP up
Blood supply to kidneys
Receives approx 1.2-1.3L/min - approx 20% CO
What are the 3 capillary beds of the kidneys
- Glomerular capillaries
- Peritubular capillaries
- Vasa recta
Filtration membrane
What is Kf
Available surface area x hydraulic conductivity
HC is very high in glomerular capillaries
4 important points about glomerular capillaries
- There is net filtration along the entire length of the glomerular capillaries
- Glomerular capillaries work at higher pressures
- Hydrostatic pressure in glomerular capillaries is relatively constant
- Colloid oncotic pressure increases in the glomerular capillaries
3 mechanisms for regulating GFR
- Renin-angiotensin system
- Autoregulation
- Sympathetic nerves
Granular juxtamedullary cells and their influence on BP
Cells are located in AA
- Store and secrete renin, resulting in Angotensin II formation (when renin is released, it chops a piece of angiotensinogen to form Ang I - then converted to Ang II = POTENT VASOCONSTRICTOR)
- Directly increases total PR and systemic BP
- Indirectly increases Na+ reabsorption, K+ secretion and ECF volume
NOTE: ACE (Ang converting enzyme) inhibitor treats BP
Myogenic mechanism for autoregulation of GFR
Tubuloglomerular feedback mechanism
ATP is an important neurotransmitter
Response of Macula Densa
No Ca2+ represented by black
Sympathetic nerves
Tonic level of sympathetic input - vasomotor tone
Losing fluid - support vol to get blood to the brain
SEE CASE STUDY
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