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WJEC A Level Biology > Homeostasis and the kidney > Flashcards

Homeostasis and the kidney Flashcards

1
Q

What are the kidney’s 2 main functions

A

Osmoregulation

Removal of metabolic waste

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2
Q

What are the excretory products in humans

A

Bile products
CO2
Urea

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3
Q

What is the excretory product in birds

A

uric acid

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4
Q

What is the excretory product in fish

A

ammonia

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5
Q

How are excess amino acids broken down

A

In the liver in a deamination reaction to produce urea which is a safe waste product

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6
Q

What is homeostasis

A

The maintenance of constant internal conditions

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7
Q

What is negative feedback

A

Negative feedback is a reaction that causes a decrease in function. It occurs in response to some kind of stimulus. Often it causes the output of a system to be lessened; so, the feedback tends to stabilize the system.

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8
Q

Name the parts of the nephron in the order blood passes through them

A 
Glomerulus
Bowman's Capsule
Proximal Convoluted Tubule
Loop of Henle
Distal Convoluted
Collecting Duct
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9
Q

Name the parts of the kidney from the centre outwards

A

Pelvis
Medulla
Cortex

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10
Q

What is the function of the glomerulus and Bowman’s Capsule

A

Ultrafiltration. High hydrostatic pressure in the capillary knot of the glomerulus forcing small molecules into the Bowman’s capsule.

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11
Q

How is high hydrostatic pressure generated in the glomerulus

A

Blood enters in the afferent arteriole which is wider than the efferent arteriole through which it leaves, causing a build up of pressure

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12
Q

What are the layers in the Bowman’s space

A

Capillary Walls
Basement Membrane
Squamous epithelial layer

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13
Q

How do you calculate the blood filtration rate

A

volume of filtrate produced/volume of blood entered x100

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14
Q

Where does selective reabsorption occur

A

In the proximal convoluted tubule

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15
Q

How does selective reabsorption occur

A

Useful substances are reabsorbed through active transport and diffusion by vasa recta capillaries

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16
Q

How do glucose and amino acids enter cells in the PCT to be reabsorbed

A

Co transport with sodium ions

17
Q

How do chloride ions and water enter the cells in the PCT to be reabsorbed

A

Facilitated diffusion and osmosis

18
Q

How do the following leave the cells in the PCT to enter the bloodstream

  • glucose
  • amino acids
  • water
  • chloride ions
  • sodium ions
A
  • facilitated diffusion and secondary active transport
  • facilitated diffusion
  • osmosis
  • facilitated diffusion
  • sodium-potassium pump by active transport
19
Q

What is the glucose threshold

A

If the concentration of glucose in the blood is too high the intrinsic proteins are limited and not all the glucose is reabsorbed and so passes out in the urine

20
Q

Where does the reabsorption of water occur

A

In the loop of henle

21
Q

Describe the permeability of the descending limb of the loop of henle

A

Permeable to water, impermeable to salts

22
Q

Describe the permeability of the ascending limb of the loop of henle

A

Impermeable to water, permeable to salts

23
Q

What is the fluid inside the loop of henle referred to

A

filtrate

24
Q

What is the fluid around the loop of henle referred to

A

tissue fluid

25
Q

Describe how the reabsorption of water works

A

NaCl is actively pumped out in the ascending limb, leaving water behind. This lowers the water potential in the tissue fluid, which draws in water from the descending limb. Therefore, the filtrate is its most concentrated at the apex.

26
Q

How are animals’ loop of henle adapted to their environment

A

Longer loops allow for more water reabsorption, so desert animals have longer loops

27
Q

How is homeostasis restored when you’re dehydrated

A

Blood will have a low water potential which will be detected by the hypothalamus, which signals to the posterior pituitary gland to release ADH. This makes the DCT and convoluted tubule more permeable to water which means more is reabsorbed

28
Q

What is the action of ADH

A

Increases reabsorption of water

29
Q

What is the purpose of aquaporins

A

ADH binds to ADH receptors on the cell membrane when it is released. This causes vesicles of aquaporins to bind with the cell membrane, increasing permeability which increases the amount of water reabsorbed.

30
Q

How is a dialysis machine adapted to work

A

Counter current flow
Increased surface area
Temperature controlled
Dialysis fluid constantly replaced to maintain conc. gradient

31
Q

What is a consequence of having a kidney transplant

A

You must take immunosuppressants for the rest of your life

32
Q

What conditions can cause kidney failure

A

Diabetes and high blood pressure

33
Q

Name two types of dialysis

A

Haemodialysis and peritoneal

WJEC A Level Biology (16 decks)

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