Histology of the Renal System

Question 1

Functions of the kidney and the urinary tract

Answer 1

1. Maintain water and electrolyte homeostasis, body fluid osmolarity and acid base balance
2. Excretion of toxic metabolic waste products (mainly urea and creatinine)
3. Acts as an endocrine gland to produce renin and erythropoietin

Question 2

the urinary tract establishes functions 1. and 2 by

Answer 2

production storage and voiding of urine

Question 3

gross structure of the kidney

Answer 3

• 10-12cm long, 5-6cm wide, 3cm thick
• located in the retro-peritoneum
• covered by a thin but strong capsule of dense collagen fibres
• renal hilum= site of entry of the renal artery, vein and ureters

Question 4

urine drains from

Answer 4

minor calyx into major calyx into renal pelvis and into the ureter

Question 5

kidney has an

Answer 5

outer renal cortex and an inner renal medulla

Question 6

renal medulla is divided into

Answer 6

medullary pyramids with apices pointing towards the hilum called the papillae and ending on the minor calyxes

Question 7

nephron is composed of the

Answer 7

renal corpuscle and the renal tubule

Question 8

renal corpuscle is

Answer 8

the glomerulus and the renal tubule

Question 9

nephron is

Answer 9

the basic functional unit of the kidney and is composed of the renal corpuscle

Question 10

renal corpuscle

Answer 10

formed from a tuft of capillaries called the glomerulus and the cup of simple squamous epithelium at the blind end of the nephron into which the capillaries invaginate called bowmans capsule

Question 11

the tuft of capillaries is supplied by

Answer 11

the afferent arteriole and drains via the efferent arteriole

Question 12

2 layers seperate the blood from the glomerual filtrate

Answer 12

the capillary endothelium and a specialised epithelium which lies on top of the glomerular capillaries which contains epithelial cells called Podocytes

Question 13

between the 2 layers

Answer 13

is the basal lamina

Question 14

mesangial cells produce

Answer 14

a connective tissue core called the mesangium which functions include the support and removal of debris

Question 15

the loop of henle in the medulla is

Answer 15

the thin limb of the loop of henle has a thin, squamous lining in which the nuclei protrude into the tubular lumen, there is a transition into the thick ascending limb which is lined by simple cuboidal epithelial cells with abundant mitochondria

Question 16

vasa recta

Answer 16

thin walled blood vessels dip into the medulla from above and then climb back up to the cortex these loops of blood vessels are collectively called the vasa recta

Question 17

the distal convoluted tubules are found in the

Answer 17

renal cortex and are lined with simple cuboidal epithelium however, unlike the proximal convoluted tubule those of the distal convoluted tubule lack a brush border of extensive microvilli

Question 18

in the renal cortex

Answer 18

the collecting ducts along the straight segments of the proximal and distal tubular are gathered in perpendicular bundles to the surface the kidney called MEDULLARY RAYS

Question 19

in the medulla the collecting ducts appear

Answer 19

alongside the loop of henle and the vasa recta,

Question 20

the lining of the collecting ducts is

Answer 20

simple columnar epithelium

Question 21

the juxtaglomerular apparatus

Answer 21

specialised region formed at the site where the distal convoluted tubule passes adjacent to the vascular pole of the same renal corpuscle that forms part of its very own nephron

Question 22

the juxtaglomerular apparatus is made of 3 components

Answer 22

1. Macula densa
2. Juxtaglomerular cells
3. extra-glomerular mesangial cells (lacis cells)

Question 23

macula densa

Answer 23

on the side of the distal consorted tubule nearest the afferent arteriole, the cells of the DCT are called,crowded together and there nuclei are intensely stained, the macula densas function is t send the ion composition of the distal convoluted tubule

Question 24

junta-glomerular cells

Answer 24

modified smooth muscle cells in the wall of the afferent arteriole these cells contain and secrete renin

Question 25

extra-glomerular mesangial cells otherwise known as

Answer 25

lacis cells

Question 26

extra-glomerular cells are

Answer 26

modified mesangial cells which extend outside of the renal corpuscle there exact function is unknown

Question 27

urine produced

Answer 27

by the renal papillae is collected into the minor calyx, flows into the major calyx and then into the renal pelvis

Question 28

almost all of the conducting parts of the urinary tract are lined with

Answer 28

a specialised epithelium called transitional epithelium (uroepithelium) which is stratified

Question 29

the cells at the luminal surface of the uroepithelium are called

Answer 29

umbrella cells because they are domed and facing the lumen they have a thickened impermeable membrane

Question 30

the reason the epithelium has a special structure

Answer 30

1. The variation in thickness of the cells represents different states of distention
2. the apical surface of the cells at the surface have a thickened membrane to provide a highly impermeable barrier

Question 31

below the epithelium is the

Answer 31

lamina propria and 2-3 layers smooth muscle

Question 32

length of urethra in females

Answer 32

3-5cm it is lined initially by transitional epithelium which changes to stratified squamous epithelium near its termination

Question 33

male urethra is approximately

Answer 33

20cm in length, prostatic urethra is 3-4cm and extends from the bladder through the prostate gland and is lined with transitional epithelium

• membranous urethra is approximately 1cm in length and extends from the prostate to the bulb of the penis, here the transitional epithelium becomes stratified columnar epithelium
• penile urethra approximately 15cm in length and is lined with stratified columnar epithelium which becomes stratified squamous epithelium near the tip of the penis

Question 34

prostate gland

Answer 34

tubulo-alveolar gland which is lined by simple columar secretory epithelium with a fibromuscular storma, its secretions make up half of the seminal fluid volume