15.5 The Structure And Function Of The Mammalian Kidney

Question 1

Which part of the body is the kidney attached to?

Answer 1

Back of abdominal cavity

Question 2

What two things are the kidneys involved in?

Answer 2

Excretion and osmoregulation

Question 3

What are the two purposes of the kidneys?

Answer 3

Filter out nitrogenous waste products (like urea) from the blood

Helps maintain water balance and pH of blood and therefore tissue fluid around cells

Question 4

Can you recall how blood enters and flows through the kidneys?

Answer 4

1. Renal arteries branching off from the abdominal aorta supply the kidneys with blood at arterial pressure
2. Blood that circulated through kidneys is removed by renal vein
3. Renal vein drains into inferior vena cava

Question 5

How much blood passes through the kidneys every minute?

Answer 5

90-120cm3 per minute

Question 6

How long does it take for all the blood in the body to pass through the kidneys once?

Answer 6

1 hour

Question 7

How much blood does the kidneys filter in a day?

Answer 7

180dm3 every day

Question 8

How much urine is produced in a day?

Answer 8

1-2dm3

Question 9

What are the kidneys made up of?

Answer 9

Millions of nephrons

Question 10

What are nephrons?

Answer 10

Small structures that act as filtering units

Question 11

What is the strike liquid produced by the kidneys called?

Answer 11

Urine

Question 12

What are ureters?

Answer 12

Tubes leading out of the kidney

Question 13

What is the bladder?

Answer 13

Muscular sac that stores urine

Question 14

Where does the urine collect?

Answer 14

Bladder

Question 15

How much urine can the bladder store?

Answer 15

400-600cm3

Question 16

What are the 3 main parts of the kidney?

Answer 16

Cortex, medulla, pelvis

Question 17

What is the cortex?

Answer 17

Filtering of blood takes place

Very dense capillary network carrying blood from renal artery to nephrons

Dark outer layer

Question 18

What is the medulla?

Answer 18

Contains tubules of nephrons forming kidney pyramids and collecting ducts

Lighter colour

Question 19

What does ‘pelvis’ mean in Latin?

Answer 19

Basin

Question 20

What is the pelvis?

Answer 20

Central chamber where urine collects before passing down ureter

Question 21

How long is each nephron?

Answer 21

3cm

Question 22

How many nephrons are in EACH kidney?

Answer 22

1.5 million

Question 23

What is the Bowman’s capsule?

Answer 23

Cup-shaped structure containing glomerulus

Question 24

What is the glomerulus

Answer 24

Tangle of capillaries

More blood enters than leaves it due to ultrafiltration processes taking place

Question 25

What is the proximal convoluted tubule?

Answer 25

First coiled region of tubule after Bowman’s capsule

Found in cortex

Where many of the substances needed by body are reabsorbed into the blood

Question 26

What is the loop of Henle?

Answer 26

Long loop of tubule creating region with very high SOLUTE concentration in tissue fluid deep in the kidney medulla

Contains descending limb, ascending limb and hairpin bend

Question 27

Can you describe how the loop of Henle looks like?

Answer 27

Descending limb runs from cortex -> through medulla -> hairpin bend at bottom of loop

Ascending limb travels BACK UP through medulla to cortex

Question 28

What is the distal convoluted tubule?

Answer 28

Second twisted tubule where fine-tuning of water balance of the body occurs

ADH has effect on walls

Further regulation of ion balance and blood pH takes place

Question 29

What is the collecting duct?

Answer 29

More fine-tuning of water balance takes place

Walls are also sensitive to ADH

Urine passes down collecting duct through the medulla to pelvis

Question 30

What does the nephron have around it?

Answer 30

A network of capillaries that lead into a venule and then to renal vein

Question 31

Can you briefly explain the solute concentrations of the blood leaving the kidney?

Answer 31

Greatly reduced levels of urea

Levels of glucose and amino acids almost the same
E.g. some blood is used for SELECTIVE REABSORPTION

Mineral ion concentration restored to ideal levels