Lecture 24 - Renal 1

Question 1

Nephron + collecting duct = ?

Answer 1

uriniferous tubule

Question 2

what does the cortex look like?

Answer 2

grainy due to the renal corpuscles

Question 3

what are the subdivisions of the medulla?

Answer 3

inner medulla
outer medulla containing an inner stripe and an outer strip

Question 4

how are the regions of the outer medulla classified

Answer 4

by its contents and cell types (diseases act on different regions)

Question 5

what structures do we see in the inner medulla?

Answer 5

thin loops of henle
collecting duct

Question 6

what do we see in the inner stripe of the outer medulla?

Answer 6

thin descending loop of henle
thick ascending loops of henle
collecting duct

Question 7

what do we see in the outer stripe of the outer medulla?

Answer 7

the thick portion of the descending loop of henle
the thick ascending loop of henle
collecting duct

Question 8

what is the basic structural unit of the kidney?

Answer 8

nephron

Question 9

how are the renal corpuscles formed?

Answer 9

a blind ended tube of epithelium migrates towards a blood vessel and interacts closely with it
the blood vessel becomes convoluted to form a capillary tuft, and the blind ended tube begins to engulf the capillary tuft
the engulfing continues and the tube has encased the capillaries completely

Question 10

after the epithelial tube has engulfed the capillary tuft completely, what has this established?

Answer 10

the bowmans capsule (epithelial component) and the glomerulus (endothelial component)

Question 11

what two structures interact to allow filtration in the kidney

Answer 11

the epithelia and the capillaries

Question 12

what happens to the epithelial and endothelial components during capsule development

Answer 12

the parietal epithelial layer becomes simple squamous
the visceral endothelial layer becomes specialised podocytes

Question 13

what are mesangial cells?

Answer 13

cells responsible for phagocytosis- cleans filtration membrane
they can contract and relax to change how leaky the glomerular capillaries are

Question 14

what are the poles of the renal corpuscle?

Answer 14

urinary pole (exit site)
vascular pole (BVs in and out)

Question 15

what three cell types do we find at the vascular pole

Question 16

describe juxtaglomerular cells

Answer 16

• grainy appearance due to renin production
• myoepitheial cells and so can contract

Question 17

describe lacis cells

Answer 17

• modified extraglomerular mesangial cells
• pale in colour

Question 18

describe macula densa cells

Answer 18

• large and densely stained
• important for sensing the concentration of NaCl in the distal tubule

Question 19

if there is too high NaCl, what does this say about our kidneys rate of filtration?

Answer 19

filtering too fast and there is not enough time for NaCl reabsorption

Question 20

juxtaglomerular apparatus =?

Answer 20

juxtaglomerular cells
lacis cells
macula densa cells

Question 21

how do macula densa cells react when NaCl levels are too high in the distal tubule?

Answer 21

signals to juxtaglomerular cells to release renin which causes vasoconstriction of arterioles to flow filtration and reduce NaCl flow throuh distal tubule

Question 22

how can we differentiate the urinary poler from the vascular pole?

Answer 22

urinary: cuboidal epithelium
vascular: simple squamous epithelium

Question 23

what kind of apical specialisation is on cells lining the tubules of the kidney?

Answer 23

microvilli

Question 24

describe the basement membrane of the glomerular capsule and tubules

Answer 24

continuous between the capsule and the tubules

Question 25

what colour is the basement membrane stained in the photo (exam revision)

Answer 25

blue

Question 26

what is the urinary space?

Answer 26

where urinary filtrate is collected, between the bowmans capsule and the glomerulus

Question 27

list the components of the glomerulus from the lumen of the blood vessel to the urinary space

Answer 27

1. endothelium of capillary 2. basement membrane 3. slit pores covered by a slit membrane between podocytes 4. surface coat of processes

Question 28

describe the endothelium of the capillary

Answer 28

very leaky endothelium cells, different to other endothelial cells that are designed to keep things in - like a sieve

Question 29

describe the basement membrane

Answer 29

collagen fibres in a glycoprotein matrix (proteoglycans) a lamina rara interna and a lamina rara externa with a densa layer in the middle collagen

Question 30

which lamina rara layer is closest to the capillary lumen?

Answer 30

lamina rara interna

Question 31

what is unique about the lamina rara externa

Answer 31

contains heparin sulphate proteoglycans which give the layer its negative charge

Question 32

describe the slit pores and slit membrane between podocytes

Answer 32

foot processes of podocytes have a diaphragm made of cell surface proteins and they restrict essential proteins from leaving the blood e.g albumin

Question 33

what are pedicles?

Answer 33

the secondary (foot) process of the podocytes

Question 34

are primary/major processes foot processes?

Answer 34

no

Question 35

describe the surface coat of processes

Answer 35

acidic negatively charged glycoprotein coat overlying podocytes that repels negatively charged proteins back into the bloodstream

Question 36

what three features of the filtered particle are important during filtration?

Answer 36

size, shape and charge

Question 37

what are the two types of nephrons based on the position of the glomerular capsule?

Answer 37

cortical nephron - closer to cortex of kidney juxtamedullary nephron - closer to medulla, but still in cortex

Question 38

juxtamedullary nephrons usually make what and why?

Answer 38

make concentrated urine due to long thin loops of henle in the inner medulla to do countercurrent exchnge

Question 39

what are the four common features of epithelial cells of all regions of the nephron?

Answer 39

1. cytoplasmic processes interdigitate (not a perfect cuboid for increased connection between cells) 2. tight junctions at luminal surface 3. basal lamina/basement membrane is continuous 4. intercellular space is continuous with the peritubular space (interstitial space)

Question 40

describe the histological features of a proximal convoluted tubule

Answer 40

cuboidal cells with interdigitated processes, with a microvilli brush border for active transport across cells. lots of mitochondria to fuel active transport

Question 41

describe the histological features of the thin descending limb

Answer 41

simple squamous epithelia

Question 42

describe the histological features of a distal convoluted tubule

Answer 42

cuboidal cells with integrated processes sensing cilia but no microvilli short cuboidal cells

Question 43

describe the features of the collecting duct

Answer 43

tall cuboidal cells with spherical nuclei (not columnar bc they would have elongated nuclei if so)