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25 Cards in this Set
- Front
- Back
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how does blood enter and leave the glomerulus?
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enters via afferent arterioles, leaves via efferent arterioles.
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What does a nephron comprise of?
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A bunch of capillaries surrounded by a capsule (renal corpuscle) then a renal tubule (PCT, loop of Henle, DTC).
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What does the glomerulus do? And why is it so efficient?
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Filters blood through its highly permeable capillaries. High SA + high permeability( filtration membrane).Glom pressure is high increasing filtration pressure.Filtration membr has fenestrations and podocytes restricting bld cells and proteins.
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What are the three basic functions of the kidney?
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Filtration, Absorption & Secretion.
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What is juxtaglomerulus app, what is its function?
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Initial portion of DCT lies against afferent arteriole feeding glom. both structures are modified at point of contact. Arteriole wall has juxta cells, sense bld pressure. Mascula densa cells of DCT respond to osmolarity.
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What are the peritubular capillaries?
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Surround renal tubule, they are low pressure porus capillaries that readily reabsorb solutes and h20 from tubules. ie after bld filtered thru glomerulus, some of that filtrate reabsorb by peritub capills.
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What is GFR? What factors effect it? Norm vaule?
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Volume of filtrate formed each minute from all glomeruli. factors: total SA avail for filtrn
:filtrn memb permeability :net filtration prssure. Norm value: 125mls/min |
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How does GFR change in regards to afferent and efferent arterioles?
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if afferent art constrctd: Decrease Glom pressure = Decrease GFR
If efferent art constrcitd: Increase Glom pressure = Increase GFR |
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How does GFR change in regard to Bp?
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If arterial pressure high ( Aff diln\Eff constrn) = Increase GFR.
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How is GFR regulated?
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By Mycogenic mechanism:
Increase vessel wall tension from Incr BP = aff constrn to stop Incr in GFR By Tubuloglomerular mechanism: Mascula densa resp to Decr flow & osmo = aff art diln to Incr GFR |
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PCT?
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Active reabsorption:bulk of active transp reabs done here (70%). all Glu, 90% HC03, Na
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Loop of Henle?
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Descending limb: permeb to H20.concentrates by removing h20
Ascending limb: Imperm to H20 dilutes by removing Na. counter current exhange mechanism. |
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DCT and collecting ducts?
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9% filtered Na reabsorbed. 19% filtered h20 reabsor dep on ADH.
major site of K, H secrn. under hormonal control, depdt on body needs, also on flow rate, imperm anions, K & Acid Base status, Aldosterone. |
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ADH and h20 reabs?
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No ADH = no h20 channel = dilute urine
Yes ADH = Yes h20 channel = concentrated urine. |
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Renal Clearance?
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Amount plasma cleared of partic substance in 1 minute. If RC less than GFR = nett reabsorption.
If RC greater than GFR= nett secretion. |
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Functional excretion?
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Amount of substance in urine/ amount filtered.
If < 1 (100%) = most reabs. If > 1 (100%) = subst is secreted. |
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Why do we need electrolytes?
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For many body functions, EG:
Na for action potentials, K for cardiac, Ca for muscle contrn, HC03 for Acid/Base. |
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How is it controlled?
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By hormones.
Renin- Angiotensin system Aldosterone ADH ANP(F) |
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how are changes detected?
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Osmo change: osmoreceptor cells:Hypothal & Juxtaglom.
Volume change: aterial baroreceps:in heart and Juxtaglom. (also volume recps) |
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how does ADH influence Fluid and Electrolyte balance?
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Osmorecep in hypothal detect Incr osmolarity, Poster Pituritary Rel ADH, Acts on collecting ducts.
Incr h20 reabsorption |
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What is the role of the juxtaglomerulus?
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Mascula Densa cells sense osmolarity.
Juxtaglom cells sense pressure and release renin. |
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Renin Angiotensin system 1
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Juxtaglom cells detect < in pressure, release renin.
Renin activates Angiotensin, which is then converted to Angiotensin II by ACE. |
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Renin Angiotensin system 2
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Ang II increases bp by vasoconstrn, stimulates thirst, stimulates ADH release = Incr h20 retention
Ang II stims Na Reabsorption, direct effect on proximal tubule, stims Aldosterone release. = Incr solute retention. |
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Aldosterone
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Released from Adrenal cortex. in response to: < Na, >K, RA system. Increases Na reabsorption (ie Incr solute retention.)
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Atrial Natriuretic Peptide (Factor)
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Release from cells of R atrium, in response to Incr blood volume. Decreses renin, aldosterone and ADH to Decrease water and solute retention.
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