Kidney histology

Question 1

Kidney components

Answer 1

Renal parenchyma (nephrons)
Passageways for urine calyx- renal pelvis

Question 2

Hilum of kidney

Answer 2

Site of renal pelvis and major vessels

Question 3

Cortex of kidney

Answer 3

Renal corpuscles

Convoluted tubules

Question 4

Medulla of kidney

Answer 4

Medullary pyramids/papillae
Loops of Henle
Collecting ducts
Vasa recta

Question 5

Urine journey kidney

Answer 5

Bowmans capsule –> Proximal convoluted tubule –> Peritubular capillaries –> Thin Descending limb of Henle –> Ascending limb of Henle –> Collecting tubule

Question 6

Renal artery goes into…

Answer 6

Main branch renal artery –> Interlobar artery –> arcuate artery –> interlobular artery –> afferent arteriole –> renal glomerulus –> efferent arteriole –> cortical capillary plexus or vasa recta

Question 7

Nephron

Answer 7

Funnel shaped epithelial structure where blood filtrate is processed, ultimately leaving urine
= Bowman’ capsule and renal tubule

Question 8

Renal corpuscle

Answer 8

Bowman’s capsule with its glomerulus (tuft of capillary loops) supported by mesangial cells and their ECM- mesangium

Question 9

Vascular pole

Answer 9

Site of afferent + efferent arterioles

Question 10

Urinary pole

Answer 10

Opposite where proximal convoluted tubule begins

Question 11

Renal corpuscle function

Answer 11

ultra-filtration of blood

Question 12

Bowmans capsule parietal wall

Answer 12

Single cell layer

Question 13

Bowmans capsule visceral wall

Answer 13

Podocytes

Question 14

Glomerular capillaries

Answer 14

Fenestrated endothelium

Question 15

Macula densa cells

Answer 15

Surround distal tubule

Question 16

Glomerular filtration barrier

Answer 16

Fenestrated capillary endothelium
Basement membrane
Podocyte layer of Bowman’s capsule

Question 17

Proximal convoluted tubule function

Answer 17

Reabsorption
70-80% water, Na+ and Cl-
100% AAs and glucose
Some bicarbonate reabsorbed/H+ secreted
Larger proteins, carbohydrates- endocytosis

Question 18

Proximal convoluted tubule aided by

Answer 18

Na+/K+ ATPase in basolateral membranes

Question 19

Proximal convoluted tubule Appearance

Answer 19

Microvillus brush border
Endocytotic vesicles + lysosomes
Basal and lateral interdigitations- ion transport machinery

Question 20

Loop of Henle function

Answer 20

Creates and maintains high ionic concentration of medulla

Question 21

Thin loop of Henle

Answer 21

Simple squamous epithelium
Descending- permeable to urea and water, less permeable to NaCl
Urine gains urea + loses water–> removed by vasa recta, countercurrent exchanger

Question 22

Thick ascending limb

Answer 22

Simple cuboidal
Actively transports Na+ (with Cl-) out of tubule without water
Impermeable to water
–> hypotonic urine + hypertonic concentration gradient of NaCl in medulla

Question 23

Distal convoluted tubule functions

Answer 23

Water balance- reabsorb water in presence of ADH

Electrolyte + acid base balance- Na+ reabsorption coupled to K+ or H+ secretion under control of aldosterone

Question 24

Distal convoluted tubule appearance

Answer 24

Simple cuboidal epithelium
Few microvilli or endocytotic vesicles
Basal + lateral interdigitations reflecting ion transport requirements

Question 25

Macula densa

Answer 25

Specialised region at vascular pole of nephron Dense cell packing Part of juxtaglomerular apparatus Surrounds distal convoluted tubule

Question 26

Juxtaglomerular apparatus Function

Answer 26

Regulates BP + vol | Juxtaglomerular cells, macula densa, mesangial or lacis cells

Question 27

Juxtaglomerular cells

Answer 27

Afferent arteriole | Sense decreases in BP + secrete renin

Question 28

Macula densa

Answer 28

Sense decreases Na+ content of distal tubule

Question 29

Extraglomerular mesangial or lacis cells

Answer 29

Support/info transfer

Question 30

Angiotensin II effect

Answer 30

Increases sympathetic activity Tubular Na+ Cl- reabsorption and K+ excretion H20 retention Arterial vasoconstriction --> increase in BP Causes ADH secretion - H20 absorption in collecting duct

Question 31

Collecting duct function

Answer 31

Similar to distal convoluted tubule Final concentration of urine- ADH sensitive Electrolyte + acid base balance (aldosterone sensitive) Urea diffusion helps maintain high solute concentration in medulla

Question 32

Collecting duct appearance

Answer 32

Simple cuboidal to columnar epithelium | Distinct lateral membranes (few interdigitations)

Question 33

Urinary passageways structure

Answer 33

Mucosa Submucosa Muscularis Adventitia

Question 34

Urinary passageways mucosa

Answer 34

Transitional epithelium --> plaques = membrane folds, allows distension Tight junctions/thick impervious cell membrane- barrier to urine Lamina propria but no muscularis mucosae

Question 35

Urinary passageways Submucosa

Answer 35

Merges with lamina propria

Question 36

Urinary passageways muscularis

Answer 36

``` 2-3 layers smooth muscle 1st innermost 'longitudinal' (loose spiral) 2nd circular (tight spiral) 3rd longitudinal (loose spiral) begins at lower ureter ```

Question 37

Urinary passageways Adventitia

Answer 37

Outer layer of loose connective tissue carrying larger blood vessels and nerves

Question 38

Bladder

Answer 38

Distensible reservoir | Muscular pump

Question 39

Ureters entering bladder

Answer 39

At acute angle in posterolateral wall | Filling closes the lumen --> prevents backflow

Question 40

Bladder internal sphincter

Answer 40

Formed by middle circular smooth muscle layer at 'neck' at beginning of urethra

Question 41

Micturition control

Answer 41

PNS