4. kidney structure

Question 1

name the two roles of the kidney

Answer 1

1. osmoregulation
2. excretion

Question 2

define osmoregulation

Answer 2

maintaining the water potential of blood by retaining water or removing excess water

Question 3

define excretion

Answer 3

removing nitrogenous waste, in the form of urea from the blood

Question 4

name molecules the kidney reabsorbs into the blood

Answer 4

1. amino acids
2. salts
3. glucose

Question 5

name the key features of the kidney

Answer 5

• nephron
• cortex
• medulla
• renal pelvis
• ureter

Question 6

what are nephrons

Answer 6

fine tube structures, which carry out filtration and reabsorption

Question 7

define the cortex

Answer 7

outer layer, containing filtration parts of the nephrons

Question 8

define the medulla

Answer 8

the inner layer which contains tubes carrying filtered wastes to the centre of the kidney

Question 9

what does the medulla contain

Answer 9

• loop of Henle
• collecting duct parts of the nephrons

Question 10

what is the renal pelvis

Answer 10

where all the collecting ducts come together and connect to the ureter

Question 11

what is the role of the ureter

Answer 11

transports urine to the bladder to be excreted

Question 12

what are the two main stages of the kidneys

Answer 12

1. ultrafiltration
2. selective reabsorption

Question 13

outline ultrafiltration

Answer 13

• blood enters the glomerulus from the renal artery through the afferant arteriole
• blood flows through the knot of capilleries, leaving through the efferent arteriole, which has a narrower lumen
• creating a high hydrostatic pressure
• forces plasma through cappillery fennestrations into a filter called bowmans capsule
• bowmans capsule is specialised containing podocytes, around the capillary wall forming filtration slits
• these slits increase surface area increasing the efficiency of ultrafiltration

Question 13

what is the second part of the kidneys

Answer 13

selective reabsorption

Question 14

where does ultrafiltration and selective reabsorption take place?

Answer 14

nephron

Question 15

outline selective reabsorption

Answer 15

• glomerular filtrate flows from the bowmans capsule into the proximal convoluted tube (PCT)
• 85% of filtrate is reabsorbed into blood

Question 16

what is in the 85% filtrate reabsorbed into the blood?

Answer 16

• glucose
• amino acids
• inorganic salts
• most water by osmosis

Question 17

how are the cells lining the PCT specialised to maximise reabsorption?

Answer 17

• folded membrane to increase surface area
• lots of membrane proteins for facilitated diffusion
• lots of ribosomes to make membrane proteins
• lots of mitochondria to provide ATP for protein synthesis