Embryology and Histology

Question 1

When do the metanephros develop?

Answer 1

(most mature form of kidney)

• develop around 5 weeks
• begin to function between 9-11 weeks

Question 2

What happens at days 28 and 32 of development?

Answer 2

• 28= ureteric bud sprouts from distal mesonephric ducts

- 23= ureteric buds penetrate the metanephric blastema

Question 3

When does kidney agenesis happen?

Answer 3

when there is no ureteric bud to join the metanephric mesenchyme

Question 4

What do the ureteric bud and the metanephric blastema become?

Answer 4

ureteric bud- collecting system

metanephric blastema- nephron

Question 5

When do the kidneys ascend?

Answer 5

between 6-9 weeks

Question 6

What does the bladder develop from?

Answer 6

the primitive urogenital sinus and so does the pelvic urethra

Question 7

What does the cloaca contribute to?

Answer 7

both the hindgut and the urogenital systems

Question 8

What layer are the kidneys derived from?

Answer 8

the mesoderm

Question 9

What are the pronephric and mesonephric tubules function?

Answer 9

pronephric= function is only development
mesonephric= functional

Question 10

What does the mesanephric duct form?

Answer 10

the ureters

Question 11

Where does the collecting duct system come from?

Answer 11

the ureteric bud and calices

Question 12

Where does the rest of the nephron come from?

Answer 12

the metanephric mesenchyme

Question 13

What are the roles of the kidney and urinary tract?

Answer 13

• maintain water and electrolyte homeostasis, body fluid osmolarity and acid-base balance
• excrete toxic metabolic waste products (urea and creatinine)
• act as an endocrine gland making renin and erythropoietin

Question 14

What is the kidney capsule?

Answer 14

connective tissue lining the renal sinus

Question 15

What is the role of the renal corpuscle?

Answer 15

production and collection of glomerular filtrate

Question 16

What is the role of the PCT?

Answer 16

reabsorption of water, proteins, amino acids, carbohydrates and glucose

Question 17

What is the role of the loop of Henle?

Answer 17

creation of hyper osmotic environment in medulla

Question 18

What is the role of the DCT?

Answer 18

acid-base and water balance (absorption of water, Na, bicarbonate, excretion of K and H ions)

Question 19

What is the Bowman’s capsule made up of?

Answer 19

simple squamous epithelium

Question 20

Where are the podocytes?

Answer 20

on top of the glomerular capillaries

Question 21

What are the two poles of the renal corpuscle?

Answer 21

• vascular

- urinary

Question 22

What are the three components to the glomerular filter>

Answer 22

• fenestrated endothelium of capillary wall
• thick basement membrane (shared by endothelium and podocytes)
• filtration slits between pedicels

Question 23

What happens in the PCT?

Answer 23

• 70% of sodium (ACT) and water (diff) is reabsorbed

- almost all glucose and amino acids are reabsorbed (cotrans)

Question 24

What is the outline of the PCT?

Answer 24

larger than the DCTs and have a less well defined luminal margin due to the brush border

Question 25

What are the thick limbs of the loop of Henle lined with?

Answer 25

simple cuboidal epithelium

Question 26

What are the thin limbs of the loop of Henle lined with?

Answer 26

simple squamous epithelium

Question 27

What is the blood supply to the medulla?

Answer 27

vasa recta which are thin blood vessels which dip down into the medullar from above and climb back up to the cortex

Question 28

What is the outline of the DCT?

Answer 28

smaller than the PCTs and have a more obvious luminal margin as they have only sparse apical microvilli

Question 29

What is reabsorption of Na in the DCT controlled by?

Answer 29

aldosterone which is secreted by the adrenal cortex and results in more Na and H2O retention so increased BP

Question 30

Why does the medulla appear stripped?

Answer 30

lines towards the cortex is the collecting ducts all lining up perpendicular to the kidney surface called medullary rays

Question 31

What does high ADH cause?

Answer 31

increased permeability to duct and water out of lumen so concentrated urine

Question 32

What are the conducting parts of the urinary tract made of?

Answer 32

transitional epithelium or urothelium which is stratified with umbrella cells at luminal surface

Question 33

What does the urothelium with umbrella cells cause?

Answer 33

• highly impermeable barrier

- variability in thickness at different states of distension

Question 34

What is below the transitional epithelium in the bladder?

Answer 34

lamina propria of connective tissue and 2-3 layers of smooth muscle

Question 35

What are the layers of the ureter?

Answer 35

• transitional epithelium
• lamina propria of connective tissue (these two make up mucosa)
• covered by inner longitudinal smooth muscle
• and outer circular layer
• surrounded by adventitia/serosa
• near bladder there are three layers of serosa around all of this

Question 36

What is the micturition reflex controlled by?

Answer 36

parasympathetic ganglia innervated by neurons in the sacral spinal cord which are in the muscle and adventitia

Question 37

What is the urethra in females made up of?

Answer 37

transition to stratified squamous near the end

Question 38

What is the urethra in males made of?

Answer 38

• prostatic urethra is transitional
• membranous urethra is transitional and then stratified columnar
• penile urethra is stratified columnar to stratified squamous near penis tip