Histology Of Kidney
Renal glomerulus
produces ultrafiltrate of blood (<~70 kDa)
- afferent arteriole delivers blood to capillary network
- basal lamina acts as filter
- podocytes (with foot-like processes form cells of filtration barrier)
- particles pass through capillary fenestrations, basal lamina and gaps
between foot processes of podocytes
- efferent arteriole takes filtered blood away through vasa recta
- distal convoluted tubule passes between afferent and efferent arterioles
giving juxtaglomerular apparatus
Juxtaglomerular apparatus
- cells of distal convoluted tubule facing glomerulus form macula densa
- also includes juxtaglomerular cells and extraglomerular mesangial cells
- decreased sodium concentration or decreased water volume lead to release
of renin from these cells
- renin converts angiotensinogen to angiotensin I. In lung angiotensin I
converted to angiotensin II
- Angiotensin II causes release of aldosterone from zona glomerulosa of
suprarenal gland
- aldosterone causes increased distal tubule reabsorption of water
- angiotensin II is also a potent vasoconstrictor
Sections of tubule
- Proximal convoluted
- proximal straight
- thin segment
- distal straight
- distal convoluted
Cortical nephrons
- corpuscle in outer section of cortex
- very short loop of Henle
- efferent arterioles branch into network of peritubular capillaries
Juxtamedullary nephrons
- corpuscle in inner section of cortex
- long loop of Henle extending into medulla
- efferent arterioles give off vasa recta in addition to peritubular
capillaries
Blood flow
- from renal artery to
- interlobar arteries
- give arcuate arteries
- give interlobular arteries - many branches to renal glomeruli
- flows through renal glomerulus
- from juxtamedullary nephrons flow down as vasa recta
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