Histology

Question 1

What are the functions of the kidney and the urinary tract?

Answer 1

1. Main water and electrolyte homeostasis, body fluid osmolarity and acid-base balance
2. Excrete toxic metabolic waste products (mainly urea and creatinine)
3. Act as an endocrine gland, producing renin(an enzyme almost) and erythropoietin

Question 2

location of the kidney

Answer 2

retroperitoneal stucture

Question 3

What is the kidney covered by?

Answer 3

thin but strong capsule made of dense collagen fibres

Question 4

What is the use of the hilum?

Answer 4

site of entry of the renal artery, exit of vein and ureter

Question 5

What is the medulla made of?

Answer 5

Pyramids -> pointing towards the hilum with the apices called the papillae

Question 6

What does the renal pelvis subdivide into?

Answer 6

Major calyx -> minor calyces -> forms a tubular structure at the apices of the pyramids

Question 7

Where is the papillae of the pyramid located and what is its use?

Answer 7

urine drips from the medulla into the calyx

Question 8

What are the functions of the renal column?

Answer 8

Renal columns -

1. don’t anchor the cortex down
2. provide a conduit for the incoming blood supply - hence blood supply to the medulla from the cortex

Question 9

What is the fat pad of the kidney called?

Answer 9

renal sinus

Question 10

What are the two parts of the nephron?

Answer 10

Renal corpuscle and renal tubules

Question 11

What are the parts of the renal tubule?

Answer 11

proximal collecting tube, ascending and desceding loop, distal colelcting tubule

Question 12

What is the renal corpuscle formed off?

Answer 12

Formed of a tuft of capillaries -> glomerulus and the cup of simple squamous epithelium at the blind end of the nephron which the capillaries invaginate into (bowman’s capsule)

the t

Question 13

What are the tuft of capillaries supplied by?

Answer 13

Afferent arteriole and rained by an efferent arteriole

cells of the simple squamous epithelium covers the capillaries

Question 14

what are the Outer epithelial cells ?

Answer 14

podocytes - filtration slits - outside of the capillaries
nasal lamina- thick btw the two, 6x thicker than normal basal lamina (epithelium continous with the podocytes)
fenestrated and allows the ease of flow of the fluid component through it
core of the capillaries - mesangial cells –> connective tissue -> mesangium (sits at the core of the structure)

GFR (100ml/ min)»> production of urine (1ml/min)

Glomerulus hangs from the corpuscle via the blood vessels, opposite that is the beginning of the renal tubule

each has a vascular pole (entry and exit) and a urinary pole (for the renal tubule)

Question 15

What is the glomerular filtrate?

Answer 15

it is the

Question 16

Which vessel is larger?

Answer 16

afferent arteriole > efferent arteriole

Question 17

What are the mesangial cells and the mesangium?

Answer 17

core of the loops

Question 18

extra-glomerular mesangial cells

Answer 18

when the mesangium extends from the vascular pole

Question 19

wehre is the podocyte present?

Answer 19

outside the capillary (capillary - endothelial cells, basal lamina, podocyte)

Question 20

Proximal convoluted tubule -

Answer 20

reabsorption of the waterm electrolytes
70% of the sodium (active transport) and water is reabsorbed

high specialised - cuboidal epithelial cells - brush border villi/ extnesive brush border

junctional complexes at the apical ends -> if these cells are birnging the amino acids from the ourside and they sealit off via tight junctions to prevent the random going back

they are larger than the distal convoluted tubules

Question 21

Loop of henle

Answer 21

dives into the medulla as a thick tube and then becomes a small one lined by squamous epithelium, turns around on itself and then goes back to being a thick limb

thick descending loop - thin descending loop - thin ascending loop - thick ascending loop

creates a hyper-osmotic environment - surrounding the tubules (salty region)

loses salt to the medulla

Question 22

how does the blood not change the osmolarity of the medulla?

Answer 22

blood vessels go down with the descending and then turn around and go via a less osmotic environment and dont change the medulla osmolarity

Question 23

vasa recta

Answer 23

the straight vessels which either go down or come straight up from the medulla

Question 24

Distal convoliuted tubule

Answer 24

fine tune your filtrate - acid base changes are bade here, border balance and water reabsorption can be altered, iron concentration can also be altered

lacks the huge microvillour border/ brush boder like int he proximal ct, lots of mitochondria, clear cut apical border

Question 25

Collecting system

Answer 25

end of the renal tubules

Question 26

ducts of bullemi

Answer 26

largest of the collecting ducts

Question 27

medullary rays

Answer 27

present in the cortex
pointed its in the cortex –> aggregation of collecting ducts in the cortex, distal and collecting tubules poitning towards the medulla

drink lots of water –> water goes through the collkecting duct and water doesnt go to the hyper-osmolaric environment and tje collecting duct isnt permeable to water

if thirsty -> the collecting duct becomes permeable and ater passess via the medulla into the surrounding the tissue and hence the tissue becomes really concentrated

collecting duct cells –> poorly stained, less busy, can differentiate each of the cells individually

Question 28

medullary rays

Answer 28

present in the cortex
pointed its in the cortex –> aggregation of collecting ducts in the cortex, distal and collecting tubules poitning towards the medulla

drink lots of water –> water goes through the collkecting duct and water doesnt go to the hyper-osmolaric environment and tje collecting duct isnt permeable to water

if thirsty -> the collecting duct becomes permeable and ater passess via the medulla into the surrounding the tissue and hence the tissue becomes really concentrated, controlled reabsorption of water via the ADH

collecting duct cells –> poorly stained, less busy, can differentiate each of the cells individually (in PCT and DCT - youcan tcompletely differentiate btw the cells)

Question 29

transitional epithelium or urothelium

Answer 29

it is stratified amd found in 3-6 cell layers
the cells at thr luminal surface are called the umbrella cells because they are domes
they have an impermeable membrane associated with it

they have a capacity to move over each other and change the thickness of the epithelium ,

the apical membrane facin ght eurine is highly specialised, much thicker membrane than you would find -> like a shutter on the window (ksrtc),

it is surrounded by the lamina propria
inncer longitudinallayer and circular layer of the muscle

3rd layer in the bladder - detrussor muscle

Question 30

urethra

Answer 30

females - 3-4 cm, short, initally transitional epithelium and stransitions to stratified squamous epithelium near its termination

males:
prostatic urethra - transitional epitheloium
membranous urethra - protate to bulb of penis -> stratified columnar
penile urethra- squamous epithelium