Lecture 30: Renal Histology

Question 1

Components of renal corpuscle and its role

Answer 1

Bowman’s capsule, glomerulus, renal tubule; function is to produce a filtrate of blood

Question 2

Cortical nephrons

Answer 2

Renal corpuscles located in the cortex, glomeruli empty into peritubular capillary networks, have short loops of Henle (more numerous)

Question 3

Juxtamedullary nephrons

Answer 3

Renal corpuscles located in the cortex net to the cortical-medullary junction, glomeruli empty into vasa recta, have long loops of Henle (fewer in number)

Question 4

Glomerulus

Answer 4

Capillary bed inserted between afferent and efferent arteriole; feeds into either vasa recta or peritubular capillaries

Question 5

Juxtaglomerular cells

Answer 5

Circular smooth muscle cells at vascular pole which secrete renin (hypertensive factor) when stimulated by macula densa; sympathetic innervation

Question 6

Bowman’s capsule

Answer 6

Double-layered, cup-shaped dilation of nephron consisting of inner and outer layer

Question 7

Parietal layer of Bowman’s capsule

Answer 7

Outer layer of simple squamous epithelium continuous with simple cuboidal epithelium of the proximal convoluted tubule

Question 8

Visceral layer of Bowman’s capsule

Answer 8

Inner layer of podocytes in contact with the endothelium of the glomerular capilaries

Question 9

Bowman’s space

Answer 9

Located between the parietal and visceral layers and is continuous with lumen of the proximal convoluted tubule (filtration barrier)

Question 10

What three processes are involved in the formation of urine?

Answer 10

Filtration, Reabsorption, Secretion

Question 11

Intraglomerular mesangial cells

Answer 11

Located between nearby capillaries in glomerulus and cover endothelium not covered by podocytes

Question 12

Extraglomerular mesangial cells

Answer 12

Located between the afferent and efferent arterioles at the vascular poles, associated with juxtaglomerular apparatus

Question 13

Mesangial cells

Answer 13

Contractile, modify blood flow, phagocytic, proliferative, synthesize matrix and collagen, secrete prostaglandins/endothelins, respond to angiotensin II, provide mechanical support and regulate blood flow

Question 14

Components of juxtaglomerular apparatus

Answer 14

Macula densa, extraglomerular mesangial cells, juxtaglomerular cells

Question 15

Macula densa

Answer 15

Formed by elongated, densely packed cells in wall of convoluted tubule; reversed polarity of cells (basal side faces lumen); responds to changes in Na+ and Cl- concentration in urine or hypotensin; signals RENIN release from JG cells, regulates fluid-electrolyte balance and blood pressure

Question 16

Name the parts of the renal tubule

Answer 16

Proximal convoluted tubule, descending limb of Henle, loop of Henle, ascending limb of Henle, Distal convoluted tubule - continuous with collecting ducts

Question 17

Components of renal filtration barrier

Answer 17

Fenestrated endothelium of glomerular capillaries, fused basal laminae of endothelial cells and podocytes, filtration slits

Question 18

Basal laminae of renal filtration barrier

Answer 18

Contains type IV collagen, fibronectin, laminin, heparin sulfate

Question 19

Filtration slits of renal filtration barrier

Answer 19

Created by adjacent pedicels of podocytes; covered by filtration slit diaphragm, pedicels attached to basal lamina via alpha 3 beta 1 integrins

Question 20

Describe the selectivity of the renal filtration barrier

Answer 20

Permeable to water, glucose, most ions; impermeable to proteins and negatively charged molecules (passage restricted based on size and charge)

Question 21

Characteristics of the proximal convoluted tubule

Answer 21

Extends from urinary pole to beginning of loop of Henle; simple cuboidal epithelium made of truncated pyramidal cells; apical tight junctions and brush border; basolateral infoldings, striations with abundant mitochondria; large pale staining nuclei, eosinophilic cytoplasm

Question 22

Functions of proximal convoluted tubule

Answer 22

Reabsorbs most filtrate (including water and Na+ Cl- ions), removes glucose and amino acids from filtrate; contains transporters, cotransporters, channels, exchangers