15.5 The Structure And Function Of The Mammalian Kidney

Question 1

What supplies the Kidney with blood

Answer 1

Renal arteries

Question 2

What are the cells of the kidney

Answer 2

Nephrons

These act as filtering units

Question 3

What does the kidney make

Answer 3

Urine which passes out of the kidneys down the uterus

Question 4

What does the medulla of the kidney contain

Answer 4

Tubules of nephrons that form the pyramids of the kidney and a collecting duct
Lighter colour

Question 5

What happens in the cortex of the kidney and why does it contain

Answer 5

Where filtering of blood takes place

There is a dense capillary network that carries blood from renal artery to nephrons

Question 6

What is the pelvis of the kidney

Answer 6

The central chamber where ur one is collected before leaving

Question 7

What is the job of nephrons

Answer 7

Blood is filtered

Question 8

Why are the parts of the nephron

Answer 8

Bowmans capsule 
Proximal convoluted tube
Loop of henle 
Distal convoluted tube 
Collecting duct

Question 9

What is the bowmans capsule

Answer 9

Cup shaped structure that contains the glomerulus

Question 10

What is the glomerulus

Answer 10

Where ultrafiltration takes place

Question 11

What is the proximal convoluted tube

Answer 11

The first coiled region of the tubule found in the cortex where many substances are reabsorbed

Question 12

What is the loop of henle

Answer 12

A long tubule that creates a region of very high solute concentration in the tissue fluid in the medulla part of the nephron

Question 13

What is the distal convoluted tube

Answer 13

Where fine tuning of water balance of the body takes place

The permeability of the walls to water varies in response to levels of antidiuretic hormone

Question 14

What is the collecting duct

Answer 14

Where urine passes down and more fine tuning of water takes place

Question 15

What happens to the blood that leaves the kidneys

Answer 15

It has reduced urea levels but other substances are the same amount that

Question 16

How can you investigate the kidneys

Answer 16

A protective layer of fat is removed and can be observed by using a microscope to identify nephrons

Question 17

What are the functions of the nephrons

Answer 17

Ultrafiltration and reabsorption

Question 18

What is the role of the glomerulus ultrafiltration

Answer 18

It is supplied with blood by a relatively wide afferent arteriole but the blood that leaves goes through a narrower efferent arteriole this causes considerable pressure in capillaries of glomerulus therefore blood is forced out of the capillary walls and passes through the basement membrane

Question 19

What is the basement membrane abs what’s it’s role in ultrafiltration

Answer 19

Fluid passes into it from the glomerulus capillary walls
It is made up of collagen fibres and other proteins that make up a second sieve
Most of the plasma contents passes through but blood cells abs many proteins are retained due to their size

Question 20

What does the wall as of the bowmans capsule contain abs what does this do for ultrafiltration process

Answer 20

Contains special cells called podocytes which act as an additional filter
Podocytes have pedicels (extensions) that wrap around capillaries forming slits that make sure any cells that have managed to get through the basement membrane don’t get into the tubule itself

Question 21

What does ultrafiltration do

Answer 21

Removed urea from the blood but lots of other substances like water glucose etc which need to be reabsorbed

Question 22

What is the main function of nephrons after ultrafiltration in the bowmans capsule

Answer 22

To return most of the filtered substances back into the blood via reabsorption

Question 23

What is involved in the first step of reabsorption

Answer 23

In the proximal convoluted tube all the glucose and amino acids are returned back into the blood by active transport

Question 24

How are the cells lining the proximal convoluted tube adapated for their role in reabsorption

Answer 24

Covered in microvilli which increase the surface area for reabsorption
Have lots of mitochondria to provide ATP needed for active transport

Question 25

What happens to the substances after they have been removed from the nephron

Answer 25

They diffuse into an extensive capillary network which surrounds the tubules down steep concentration gradients

Question 26

What happens to the filtrate at the end of the proximal convoluted tubule

Answer 26

It reaches the loop of henle where it is isotonic

Question 27

What does it mean that the filtrate is isotonic at the end of the proximal convoluted tube

Answer 27

It is at the same concentration with the tissue fluid surrounding it and with the blood

Question 28

What happens at the loop of henle

Answer 28

Where mammals can produce urine more concentrated than the blood It acts as a countercurrent multiplier using energy from different concentrations that result in the movement of substances from one area to another

Question 29

What does it mean that the loop of henle acts as a countercurrent multiplier

Answer 29

It has different areas with different permeabilities to water and these differences depend on the high concentrations of sodium and chloride ions in tissue fluid

Question 30

What happens at the start of the loop of henle

Answer 30

The descending limb leads away from the proximal convoluted tube This is where water moves out of the filtrate The lower part of descending limb is permeable to water and runs down into the medulla of the nephron

Question 31

What happens to the filtrate entering the descending limb of the loop of henle

Answer 31

It is isotonic to the blood so water passed out into the tissue fluid down the concentration gradient

Question 32

What part of the loop of henle is and isn’t permeable to chloride and sodium ions

Answer 32

Descending loop isn’t permeable to chloride and sodium ions so no active transport happens here Start of the ascending loop is very permeable to chloride and sodium ions so they are pumped out of it

Question 33

What happens at the 2nd section of the ascending limb | To chloride sodium and water

Answer 33

Sodium and chloride are actively pumped out into the medulla tissue fluid against conc gradient Ascending limb is impermeable to water so water cannot follow the chloride and sodium ions so they fluid left in the ascending limb is very dilute

Question 34

What happens when the dilute fluid reaches the top of the ascending limb

Answer 34

It becomes hypotonic to the blood and enters the distal convoluted tubule abs collecting duct

Question 35

What is the role of teh distal convoluted tubule

Answer 35

balancing the water needs to the body The wall permeability will depend on the levels of ADH It also balances pH of blood

Question 36

What happens in the collecting duct

Answer 36

Here is where the concentration and volume of urine is determined The permeability of the collecting duct to water is controlled by ADH level by determine how much water should be absorbed