lecture 29 - the nephron

Question 1

properties of cortical nephrons

Answer 1

85% of nephrons
- lie mainly in the cortex

Question 2

properties of juxtamedullary nephrons and what are the important for

Answer 2

• extend deep into the medulla
• important for the formation of concentrated urine

Question 3

what is the general function of nephrons

Answer 3

selectively filter blood,

return to blood anything to be kept and carry waste away for storage and expulsion

Question 4

what does a nephron contain

Answer 4

• a glomerular capsule
• renal tubes
• a collecting duct

Question 5

what is each nephron associated with

Answer 5

• a glomerulus
• peritublar capillaries

Question 6

what are glomerular capillaries

Answer 6

thin walled single layer of fenestrated endothelial cells = specialised for filtration

Question 7

what are glomerular capillaries fed and drained by

Answer 7

arterioles

Question 8

what are pertibular capillaries

Answer 8

wrap around renal tubules = specialised for absorption

Question 9

what do pertibular capillaries receive

Answer 9

• filtered blood from glomerulus via efferent arterioles
• reabsorbed filtrate from nephron

Question 10

what are vasa recta

Answer 10

extensions that follow nephron loops deep into the medulla = only found with juxtamedullary nephrons

Question 11

what is the renal corpuscle

Answer 11

where capillary and nephron meet = site of filtration

• glomerulus is enclosed by glomerular capsule

Question 12

what are the two layers of the glomerular capsule and what is between them

Answer 12

outer parietal layer = of simple squamous cells
inner visceral layer = of podocytes

• between the two layers = capsular space - which receives filtrate

Question 13

what do podocytes surround

Answer 13

the glomeruluar capillaries

Question 14

what are podocytes

Answer 14

vary branch, vary specialised epithelium

Question 15

what are pedicels

Answer 15

branches from intertwining foot processes

Question 16

what forms between pedicels

Answer 16

filtration slits

Question 17

what happens at filtration slits

Answer 17

filtered blood foes through these slits and passes in the capsular space

Question 18

what are three layers of the filaration barrier (blood urine barrier / glomerular capsular membrane )

Answer 18

• fenestrated endothelium of glomerular capillary
• fused basement membrane
• filtration slits between the pedicels of the podocytes

Question 19

what happens at the proximal convoluted tubule

Answer 19

bulk reabsorption

Question 20

what is the proximal convoluted tubule surrounded by

Answer 20

peritubular capillaries

Question 21

what is the structure of the proximal convoluted tubule

Answer 21

• dense microvilli on luminal membrane
• highly folded basolateral membrane
• many mitochondria for active transport
• leaky epithelium

Question 22

what is the epithelium of the proximal convoulated tubule

Answer 22

cuboidal epithelial cells

Question 23

what is the structure of the thick ascending and thick descending limbs of the nephron loop

Answer 23

thick descending = similar to PCT structure
thick ascending limb = similar to DCT structure

Question 24

what is the structure of the thin ascending and thin descending limbs of the nephron loop

Answer 24

thin descending limb = simple squamous epithelium
thin ascending limb = simple squamous epithelium

Question 25

what is the epithelium of the distal convoluted tubule

Answer 25

cuboidal epithelium, but thiner than PCT

Question 26

what is the structure of the distal convoluted tubule

Answer 26

• few microvilli
• fewer mitochondria
• reabsorption influenced by aldosterone

Question 27

what is the function of the collecting duct

Answer 27

• fine tuning
• filtrate from several DCTs drain into one collecting duct, which empty into papilla

Question 28

what is the structure of the collecting duct

Answer 28

wall of epithelium

• principle cells = reabsorption
• intercalated discs = acid / base balance