Histology

Question 1

what are the functions of the kidneys and urinary tract

Answer 1

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 producing renin and erythropoietin

Question 2

what covers the kidney

Answer 2

thin but strong capsule of dense collagen fibres (is continuous with the connective tissue of the renal sinus)

Question 3

what is the hilum of the kidney

Answer 3

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

Question 4

what makes up the medulla

Answer 4

medullary pyramids with apices pointing towards the hilum (papillae) (where urine drops off into the minor calyx)

Question 5

what is a lobe of the kidney

Answer 5

a medullary pyramid and its associated cortical tissue

Question 6

where does the medulla gets its blood supply from

Answer 6

the cortex

Question 7

what fills the renal sinus

Answer 7

fat

Question 8

what is the nephron

Answer 8

the basic functional unit of the kidney

Question 9

what makes up the nephron

Answer 9

renal corpuscle and renal tubules

Question 10

what makes up the renal corpuscle

Answer 10

glomerulus (capillaries) and bowens capsule (cup of simple squamous epithelium at the end of the nephron that the capillaries invaginate into)

Question 11

what is the function of the renal corpuscle

Answer 11

production and collection of glomerular filtrate

Question 12

what supplies and drains the glomerulus

Answer 12

afferent (supplies) and efferent (drains) arteries

Question 13

what are podocytes

Answer 13

specialised epithelium cells that line bowmans capsule (lie of top of the capillaries of the glomerulus)

Question 14

how does blood get from the glomerulus capillaries to the tubules (aka what are the three layers of the glomerular filter)

Answer 14

• endothelium (is fenestrated)
• thick basal lamina
• pododcytes (pedicles which form filtration slits)

Question 15

what is the mesagium

Answer 15

made of mesangial cells, is the stalk like core of the glomerulus
provides support and removal of debris within the renal corpuscle

Question 16

what is the is the glomerular filrate rate

Answer 16

100-125 ml/min

Question 17

what are the two poles of the renal corpuscle

Answer 17

vascular pole (where afferent/efferent arteries connect) 
urinary pole (where glomerular filtrate leaves)

Question 18

what cells have a saw tooth appearance

Answer 18

podocytes

Question 19

what is the role of the proximal convoluted tubule

Answer 19

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

70% of sodium (active transport) and water (diffusion) is reabsorbed as is almost all amino acids and glucose (co-transport)

Question 20

what is a PCT cell, what is it like

Answer 20

cell of the proximal tubule

cuboidal epithelial cell
has extensive brush border (microvilli) and invaginated basal lamina to increase SA

Question 21

what makes up the medulla

Answer 21

parallel tubules, the loops of henle and the collecting ducts + looping vascular network

Question 22

what lines the loop of henle

Answer 22

thick limbs- simple cuboidal epithelium

thin limbs- simple squamous epithelium

Question 23

what are the parts of the loop of henle

Answer 23

thick descending limb (proximal straight tubule)
thin descending limb
thin ascending limb
thick ascending limb (distal straight tubule)

Question 24

what is the role of the loop of henle

Answer 24

creation of the hyperosmotic environment in the medulla

Question 25

what is hyperosmotic

Answer 25

a fluid having a great conc of solutes than a normal extracellular fluid (more salty), increased osmotic pressure (water moves into capillaries (like oncotic)

Question 26

how does the loop of henle create and maintain a hyperosmotic interstitium

Answer 26

as permability to water and ion and active transport of ions varies in the different parts

Question 27

explain the blood supply of the medulla

Answer 27

vasa recta- loops of thin vessels that come down from the cortex and then go back up normal vessels going through would carry away the salts in the interstitium and reduce high osmotic gradient

Question 28

what is the role of the distal convoluted tubule

Answer 28

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

Question 29

how do the proximal and distal convoluted tubules differ

Answer 29

distal has smaller/ lacks a microvillus border distal small tubules that proximal

Question 30

what controls the re absorption of Na in the distal convoluted tubule

Answer 30

aldosterone - causes greater Na+ and water retention (increases BP)

Question 31

what controls the reabsorption of water

Answer 31

ADH

Question 32

what joins into the collecting duct

Answer 32

connecting tubules

Question 33

what forms medullary rays (stripes in medulla)

Answer 33

the straight segments of the proximal and distal tubules | the collecting ducts

Question 34

how does ADH work

Answer 34

(from post pit) increases the permeability of the collecting duct to water in high ADH, because of the high salt content of the interstitial fluid, water passes through the lumen as is goes through the medulla ADH= concentrated urine

Question 35

what is the function of the collecting tubules and collecting ducts

Answer 35

controlled reabsorption of water under the control of ADH | carries urine out into calyces

Question 36

describe the flow of urine

Answer 36

``` produce at renal papilla minor calyx major calyx renal pelvis ureter bladder urethera ```

Question 37

what lines (almost) all of the conducting parts of the urinary tract

Answer 37

transitional epithelium (uroepithelium) (cells at luminal surface are domed a.k.a umbrella cells) highly IMpermeable

Question 38

why does the epithelium of the conducting parts of the urinary system has variable thickness

Answer 38

to allow for different states of distention

Question 39

what is below the epithelium of the conducting parts of the urinary system

Answer 39

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

Question 40

what ganglia in the muscle of the bladder

Answer 40

parasympathetic from sacral spine (provide micturition relfex)

Question 41

how long is the urethra in femaled

Answer 41

4cm

Question 42

what lines the female urethra

Answer 42

transitional epithelium | stratified near its termination

Question 43

what lines the male urethra

Answer 43

prostatic urethra- transitional epithelium membranous urethra- stratified columnar penile urethra- stratified columnar epithelium, becomes stratified squamous at tip

Question 44

how long is the male urethra

Answer 44

20cm prostatic (from bladder through prostate) 3-4cm membranous (from prostate to bulb) 1cm penile urethra 15cm