Term
| Glomerular capillaries are 100-400 times more permeable to ions than other capillaries in the body because of: |
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Definition
- high hydrostatic pressures
- large pores in the capillary endothelium
- large pores in the basement membrane
- filtration slits between the pedicels (foot process)
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Term
| Type of Carbonic Anhydrase Inhibitor |
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Definition
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Term
| Normal Physiology of Urine Formation: Proximal Convoluted Tubule |
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Definition
- 60-70% of filtered Na+ reabsorbed
- 100% of glucose, amino acid, vitamins, proteins reabsorbed
- 80-90% of filtered bicarbonate reabsorbed
- site of active secretion of weak acids and bases
This is the site of action of carbonic anhydrase inhibitor acetazolamide |
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Term
| Normal Physiology of Urine Formation: Descending Limb of Loop of Henle |
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Definition
water is reabsorbed
urine is concentrated |
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Term
| Normal Physiology of Urine Formation: Ascending Limb of Loop of Henle |
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Definition
- 20-25% of filtered Na+ reabsorbed
- Loop diuretics (furosemide) inhibit Na+/2Cl-/K+ symport
- Impermeable to water but Na+ is reabsorbed so osmolarity decreases
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Term
| Normal Physiology of Urine Formation: Distal Convoluted Tubule |
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Definition
- 5-10% of Na+ reabsorbed
- thiazide diuretics inhibit Na+/Cl- symport
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Term
| Normal Physiology of Urine Formation: Late Distal Tubule and Collecting Duct |
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Definition
- 2-3% of Na+ reabsorbed
- Aldosterone increases Na+ reabsorption by increasing the expression Na+/K+ ATPase pumps on the basolateral membrane and Na+ channels on the apical membrane
- ADH promotes water reabsorption at this site
- this is the site of action of K+ sparing diuretics (amiloride, triamterene, spironolactone)
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Term
| Juxtaglomerular Apparatus consists of: |
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Definition
- afferent and efferent arterioles
- distal tubule/loop of henle (TAL)
- mesangial cells
- Juxtaglomerular cells (granular cells)
- Macula Densa cells
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Term
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Definition
AKA Granular cells
releases renin
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Term
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Definition
Localized in the distal tubule/loop of henle
Senses the amount of Na+ in the distal tubule |
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Term
| How does GFR decrease via Tubuloglomerular Feedback (TGF)? |
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Definition
- If the GFR increases, this will increase the amount of NaCl that eventually makes it to the loop of henle
- The macula densa cells of the distal convoluted tubule/loop of henle will detect this increased [NaCl]
- The macula densa sends a signal to the afferent arteriole and it will constrict, thereby increasing pre-glomerular resistance
- Constricting the afferent arteriole will decrease the amount of volume entering the glomerulus and GFR will decrease
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Term
| The molecular mechanisms of tubuloglomerular feedback (TGF) |
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Definition
- uptake of Na+, K+, and Cl- via Na+/K+/2Cl- symporter
- generation of adenosine via Na+/K+ ATPase
- activation of adenosine A1 receptor
- increase in Ca2+ in mesangial cells
- propagation of Ca2+ signal through gap junctions
- vasoconstriction and inhibition of renin secretion due to increased levels of Ca2+ in the vascular smooth muscle cells and granular cells, respectively
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