15.5 The Structure And Function Of The Mammalian Kidney Flashcards

1
Q

What supplies the Kidney with blood

A

Renal arteries

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2
Q

What are the cells of the kidney

A

Nephrons

These act as filtering units

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3
Q

What does the kidney make

A

Urine which passes out of the kidneys down the uterus

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4
Q

What does the medulla of the kidney contain

A

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

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5
Q

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

A

Where filtering of blood takes place

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

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6
Q

What is the pelvis of the kidney

A

The central chamber where ur one is collected before leaving

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7
Q

What is the job of nephrons

A

Blood is filtered

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8
Q

Why are the parts of the nephron

A
Bowmans capsule 
Proximal convoluted tube
Loop of henle 
Distal convoluted tube 
Collecting duct
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9
Q

What is the bowmans capsule

A

Cup shaped structure that contains the glomerulus

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10
Q

What is the glomerulus

A

Where ultrafiltration takes place

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11
Q

What is the proximal convoluted tube

A

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

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12
Q

What is the loop of henle

A

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

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13
Q

What is the distal convoluted tube

A

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

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14
Q

What is the collecting duct

A

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

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15
Q

What happens to the blood that leaves the kidneys

A

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

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16
Q

How can you investigate the kidneys

A

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

17
Q

What are the functions of the nephrons

A

Ultrafiltration and reabsorption

18
Q

What is the role of the glomerulus ultrafiltration

A

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

19
Q

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

A

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

20
Q

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

A

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

21
Q

What does ultrafiltration do

A

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

22
Q

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

A

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

23
Q

What is involved in the first step of reabsorption

A

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

24
Q

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

A

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

25
Q

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

A

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

26
Q

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

A

It reaches the loop of henle where it is isotonic

27
Q

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

A

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

28
Q

What happens at the loop of henle

A

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

29
Q

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

A

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

30
Q

What happens at the start of the loop of henle

A

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

31
Q

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

A

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

32
Q

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

A

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

33
Q

What happens at the 2nd section of the ascending limb

To chloride sodium and water

A

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

34
Q

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

A

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

35
Q

What is the role of teh distal convoluted tubule

A

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

36
Q

What happens in the collecting duct

A

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