B3.3.4 Inside the Kidney

Question 1

Function of capsule

Answer 1

Outer membrane of kidney which helps maintain its shape and protect from damage

Question 2

Cortex

Answer 2

Outer part of kidney

Question 3

Where inside the kidney is urine produced?

Answer 3

Microscopic tubules called nephrons

Question 4

How many nephrons approx in each kidney

Answer 4

1 mill

Question 5

Where is the top of the nephron found

Answer 5

The cortex

Question 6

Where is the lower section (loop of Henlé) found

Answer 6

Medulla

Question 7

State which blood vessels allow blood to enter and leave the kidney

Answer 7

Renal artery (enter)
Renal vein (leave)

Question 8

Describe selective reabsorption (3/4)

Answer 8

As the filtrate passes through the PCT, all of the glucose is reabsorbed and some of the water and salts
Next the filtrate travels down through the loop of Henle where water and salt levels are balanced.
The filtrate then passes through the DCT and the collecting ducts where remaining water can be further balanced using ADH secretion via negative feedback control.

Question 9

Describe excretion

Answer 9

Waste solution, urine ,collects in the collecting duct.
Travels to bladder before removed from body

Question 10

Describe the negative feedback loop when overhydration is detected.

Answer 10

Osmoreceptors in the hypothalamus detect high water levels
Hypothalamus stimulates the pituiaty gland to secrete less ADH
Collecting ducts of the kidneys show a decreased permeability to water.
Less water is reabsorbed and retained by the body
Dilute urine is produced
Salts are retained

Question 11

Describe the negative feedback loop when dehydration is detected.

Answer 11

Osmorecptors in the hypothalamus detect low water levels
Hypothalamus stimulates the pituitary gland to secrete more ADH
ADH travels in the blood to the collecting ducts of the kidneys where it stimulates an increased permeability to water.
More water is reabsorbed and retained by the body

Question 12

What does ADH do?

Answer 12

increases the permeability of the DCT and collecting duct to water
Increased permeability = Increased water reabsorbed into the blood stream from the collecting duct
Increased water reabsorbed =more concentrated urine

Question 13

Describe the process of ultrafilration.

Answer 13

Blood enters the kidney under high pressure from the renal artery
The renal artery branches into arterioles, each leading to a glomerulus
At the glomerulus there is a knot of capilaries with a narrower arteriole leaving it so increasing the blood pressure.
Increased blood pressure forces small molecules including water, glucose, salts and urea out of the glomerulus and into the Bowman’s capsule.
Large molecules such as red blood cells and protein molecules are too large to pass through the capilary wall so remain in the bloodstream.