15.5 Structure And Function Of The Mammalian Kidney

Question 1

Main roles of the kidney in the body

Answer 1

Excretion
Osmoregulation

Question 2

Blood vessel taking blood to the kidney

Answer 2

Renal artery

Question 3

Blood vessel taking blood away from the kidney

Answer 3

Renal vein

Question 4

Ureter

Answer 4

Tubes carrying urine from the kidney to the bladder

Question 5

Urethra

Answer 5

Tube through which urine exits the body

Question 6

Sphincter

Answer 6

Controls flow of urine out of the body

Question 7

Sphincter

Answer 7

Controls flow of urine out of the body

Question 8

3 main areas of the kidney

Answer 8

Cortex
Medulla
Pelvis

Question 9

Cortex

Answer 9

Dark outer layer
Filtering of blood takes place
Dense capillary network carrying blood from renal artery to nephrons

Question 10

Medulla

Answer 10

Lighter in colour
Contains tubules of nephrons which form pyramids of kidney and the collecting duct P

Question 11

Pelvis in the kidney

Answer 11

Central chamber of kidney where urine collects before passing down the ureter

Question 12

Bowman’s capsule

Answer 12

C shaped structure containing the glomerulus (tangle of capillaries)
More blood enters glomerulus than leaves due to ultrafiltration process

Question 13

Proximal convoluted tubule

Answer 13

First coiled region after BC
Found in cortex of the kidney
Reabsorption takes place

Question 14

Loop of Henle

Answer 14

Long loop of tubule that creates region with very high solute concentration in tissue fluid in medulla
Descending loop - from cortex to medulla
Ascending loop - from medulla to cortex

Question 15

Distal convoluted tubule

Answer 15

Second twisted tubule
Adjust water balance of the body
Permeability of the walls are affected by ADH

Question 16

Collecting duct

Answer 16

Urine passes down the collecting duct through the medulla to the pelvis
Walls of collecting duct are sensitive to ADH

Question 17

Concentration of substances in blood leaving the kidney

Answer 17

Lower levels of urea
Glucose, amino acids are similar to the blood entering the kidneys

Question 18

How to observe nephrons during dissection of kidney

Answer 18

Drop of hydrogen peroxide added to cut surface of the kidney
Rapid effervescence
After this, renal tubules, collecting duct and loops of Henle are clearer to see by strings of bubbles

Question 19

Difference between DCT and PCT

Answer 19

PCT has brush border
DCT have larger lumen, which are more open

Question 20

Thickness of walls of ascending loop and descending loop of Henle

Answer 20

Ascending - thicker walls
Descending - thinner walls

Question 21

Ultrafiltration

Answer 21

Forms tissue fluid in capillary beds of the body
Blood enters glomerulus under high pressure, so smaller molecules are forced out
Fluid passes through the basement membrane - made of network of collagen fibres and other proteins (sieve)

Question 22

What can pass through basement membrane?

Answer 22

Most of the plasma contents
Blood cells and proteins are retained in the capillary due to size

Question 23

Podocytes

Answer 23

Podocytes have extensions - pedicels- that wrap around capillaries forming slits so any cells, platelets or large plasma proteins do not get through into the tubule

Question 24

Reabsorption

Answer 24

Ultrafiltration removes urea, water, glucose, salts
Some of these substances are needed by the body
After Bowman’s capsule, most of the filtered substances are returned back to the blood

Question 25

Adaptations of PCT

Answer 25

Covered in microvilli - increasing SA
Many mitochondria to provide ATP needed in active transport

Question 26

How is the loop of Henle a counter current multiplier?

Answer 26

It uses energy to produce concentration gradients that cause movement of substances from one area to another

Question 27

Water balance in descending Loop of Henle

Answer 27

Upper part of descending limb is impermeable to water
Lower part of descending limb is permeable and runs down into the medulla -