Lecture 22

Question 1

What is a “double-layered, cup-shaped dilation of the nephron”? state the layers it includes

Answer 1

bowman’s capsule

has a visceral (inner) and parietal (outer) layer

Question 2

State the 2 structures that make up a single renal corpuscle

Answer 2

Bowman’s capsule and a glomerulus

Question 3

Describe the vascularization of a renal corpuscle (begin with interlobar arteries and end with renal vein

Answer 3

interlobar arteries –> arcuate arteries –> interlobular arteries –> afferent arterioles –> glomeruli –> efferent arterioles –> vasa recta/peritubular capillaries –>

(Veins begin) interlobular veins –> arcuate veins –> interlobar veins –> renal vein

Question 4

State the 3 step process of urine formation

Answer 4

Filtration occurring in the renal corpuscle

Reabsorption occurring in the renal tubule

Secretion occurring in the renal tubule

Question 5

in order to form the mesangium, what are mesangial cells found in?

Answer 5

a mesangial matrix

Question 6

Compare extraglomerular and intraglomerular mesangium

Answer 6

Intraglomerular mesangial cells are located between nearby capillaries in the glomerulus and cover endothelium not covered by podocytes

Extraglomerular mesangial cells are located between the afferent and efferent arterioles at the vascular pole and are associated with the juxtaglomerular apparatus

Question 7

Compare the contractile and phagocytic functions of the mesangium

Answer 7

Contractile: utlize cytoskeletal contractile proteins to modify blood flow through glomerular capillaries

Phagocytic: take up worn out glomerular basal lamina for recycling and also phagocytose immunoglobulins trapped in the basal lamina

Question 8

In terms of the mesangium, list what it synthesizes, what it secretes, and what hormone it responds to

Answer 8

Synthesizes matrix and collagen

Secrete prostaglandins and endothelins

Respond to angiotensin II

Question 9

State the 3 components of the juxatglomerular apparatus

Answer 9

Macula densa

Extraglomerular mesangial cells

Juxtaglomerular cells

Question 10

Describe the function of the macula densa. include what it is formed by and where it can be found.

Answer 10

Macula densa: responds to changes in sodium and chloride concentration in the urine or hypotensin and is involved in the regulation of fluid-electrolyte balance and blood pressure regulation

Signals renin release from juxtaglomerular cells

Formed by elongated, densely packed cells in the wall of the convoluted tubule (the polarity of these cells is reversed)

Question 11

Describe the function of juxtaglomerular cells. include what these cells are innervated by

Answer 11

Juxtaglomerular cells: modified smooth muscle cells associated with the macula densa and afferent arteriole

secrete renin into the bloodstream when stimulated by the macula densa

Innervated by the sympathetic nerve endings which increase renin release upon stimulation

Question 12

List, in order, the components of the renal tubule. (5 of them)

Answer 12

Proximal convoluted tubule

Descending limb of Henle (with thick and thin portions)

Loop of Henle

Ascending limb of the loop of Henle (with thick and thin portions)

Distal convoluted tubule

Question 13

State the 3 layers that form the renal filtration barrier

Answer 13

Fenestrated endothelium of the glomerular capillaries

Fused basal laminae of endothelial cells and podocytes

Filtration barrier

Question 14

Describe the “filtration barrier” portion of the renal filtration barrier (3 main portions)

Answer 14

Fenestrated endothelium of the capillaries

Basal lamina: contains type IV collagen, fibronectin, laminin, heparin sulfate

Filtration slits created by adjacent pedicles of podocytes
(Covered by filtrations slit diaphragm)
(Pedicels are attached to the basal laminin via alphabeta integrins)

Question 15

In terms of the proximal tubule, describe the type of tissue it is composed of, (the junctions and border of it) and describe the staining characteristics of it.

Answer 15

Simple cuboidal epithelium made up of truncated pyramidal cells

Apical tight junctions and brush border

Large, pale-staining nuclei and Eosinphilic cytoplasm

Question 16

Describe the basolateral region of cells of the proximal tubule and describe their organelle composition.

Answer 16

Basolateral infoldings and interdigitations

Basal striations with abundant mitochondria (to help conduct active transport across the basal membrane

Question 17

List the functions of the proximal convoluted tubule. (4 of them)

Answer 17

Reabsorbs most of the filtrate, including water

Removes essentially all glucose and AA’s from the filtrate

Reabsorbs most of the sodium and chloride ions

Characterized by a complex set of transporters, co-transporters, channels, and exchangers

Question 18

outline the path that fluid takes as it is being excreted, beginning in the glomerulus and ending in excretory passages.

Answer 18

Glomerulus

PCT

Loop of Henle

DCT

Collecting duct

Question 19

What is the major function of the loop of Henle? describe the permeability of it’s 2 “limbs”

Answer 19

Loop of Henle: major function is to establish the counter-current exchange system that creates the osmotic conditions necessary to pull water out of the distal tubule and collecting duct in the presence of ADH (vasopressin)

Descending thin limb is permeable to water, sodium, and chloride ions

Ascending thin limb is impermeable to water and actively pumps chloride ions out of the tubule, allowing sodium ions to flow

Question 20

Describe the permeability of the DCT, what type of tissue it is lined with, and it’s lumen in comparison to the PCT

Answer 20

Distal convoluted tubule: impermeable to water except in the presence of ADH

Lined with simple cuboidal epithelium with smaller cells than those of the proximal convoluted tubule

The lumen is larger than that of the proximal tubule and there is NO brush border

Question 21

True or False: The DCT and PCT cytoplasm is of very similar compostion. explain

Answer 21

False

The cytoplasm of the DCT is less eosinophilic than that of the proximal convoluted tubule

Question 22

In terms of the Collecting duct, describe the tissue it is lined with, and the 2 cell types it features.

Answer 22

Collecting duct: its wall consists of simple cuboidal epithelium.

Principle cells: reabsrob sodium ions and water and secretes potassium via ATPase pump

Intercalated cells: secrete either hydrogen ion or bicarbonate ion

Question 23

True or False: the Collecting Duct has a different embryological origin than the nephron. explain

Answer 23

True

Question 24

List the layers of the excretory passages (includes the renal pelvis, ureter, and urinary bladder) in order, beginning in the lumen. (5 layers)

Answer 24

urothelium

Mucosa

Submucosa (not clearly demarcated)

Muscualris

Adventitia (FECT external to muscularis; serosa over superior surface of bladder basically allows the bladder to “slide” along other organs in the abdominal cavity)

Question 25

Describe the layers the mucosa layer of the excretory passages is composed of (3 layers)

Answer 25

``` Mucosa: transitional epithelium (uroepithelium) ``` basement membrane lamina propria of FECT (some loose lymphoid tissue and a few smooth muscle cells)

Question 26

Describe the muscularis layer of a ureter (2 layers). include the unique characteristic of the lower 3rd of the ureter.

Answer 26

inner longitudinal layer outer circular smooth muscle coat in ureter Lower third of ureter has a third external longitudinal coat

Question 27

What forms the detrusor muscle and where does this occur?

Answer 27

Layers of smooth muscle in urinary bladder form detrusor muscle

Question 28

State and describe the 3 layers of the male urethra

Answer 28

Prostatic urethra: section of urethra passing through the prostate gland Mucosa lined with transitional epithelium Highly vascularized with veins with abundant elastic tissue Membranous urethra: tall pseudostratified columnar cells but variable Extends through the urogenital diaphragm and received striated muscle cells forming the external sphincter of the bladder Cavernous urethra: lined with pseudostratified epithelium with patches of stratified squamous epithelium

Question 29

State and describe the 2 types of glands found in the tissues of the male urethera

Answer 29

lacunae of morgagnis: invaginations of mucous membrane containing single or groups of intraepithelial mucous cells Glands of littre: branched tubular glands opening into the lacunae of Morgagni

Question 30

State the type of tissue that lines the female urethra and what glands can be found in it.

Answer 30

Female urethra: mucosa is line primarily with stratified or pseudostatified columnar epithelium with intraepithelial nests of mucous glands

Question 31

State and describe the 3 layers that make up the female urethra

Answer 31

Submucosa and adventitia are nodiscernible Lamina propria is highly vascularized with veins with an abundance of elastic tissue Muscularis has an inner longitudinal and outer circular layer of smooth muscle cells that are not well defined