Kidney Microstructure: Exploring the Juxtaglomerular Apparatus
Draw and describe the juxtaglomerular apparatus. What are its functions?
Answer:
- It is a specialized organ situated near glomerulus of each nephron.
- It is formed by.
1. Macula Densa:
- The cells of this zone are specialized renal tubular epithelia cells located at the site where thick segment of ascending limb of loop of henle.
- These cells are in direct contact with the mesengial cells, in closes contact with Ig cells and adjoins both afferent and efferent arteriole.
Function:
- Act as chemoreceptors.
- Stimulated by decreased Na+ and causes increased renin release.
2. Extraglomerular mesangial cells:
- They are situated in the triangular region bound by afferent arteriole, efferent arteriole and macula densa.
Functions:
- Phagocytic
- Secrete prostaglandin and cytokines.
- Controls the glomerular filtration.
3. Juxtaglomerular cells:
- They are modified vascular smooth muscle cells present in the wall of afferent arteriole
- They are innervated by sympathetic nerve fibers.
Function:
- Synthesize, store and release rennin.
- Regulates the renin secretion into the blood stream.
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