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Biology A level > 5.1.2 Excretion > Flashcards

5.1.2 Excretion Flashcards

excretion

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1
Q

define excretion

A

excretion is the removal of the waste products of metabolism from the body. it helps to maintain metabolism and homeostasis.

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2
Q

and example of a metabolic product we remove from the body.

A

carbon dioxide from respiration. it is expelled from the lungs in mammals and gills in fish.

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3
Q

what is the function of the hepatic artery

A

supplies the liver with oxygenated blood from the heart so the liver has a good supply of oxygen for respiration.

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4
Q

what is the function of the hepatic vein

A

takes deoxygenated blood away from the liver

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5
Q

what is the function of the hepatic portal vein

A

brings blood from the duodenum and ileum (small intestine) so it is rich in products from digestion so harmful products can be filtered out and broken down immediately

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6
Q

what units is the liver made up from

A

liver lobules

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7
Q

what is a sinusoid

A

where blood from the hepatic artery and hepatic portal vein mix

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8
Q

what do hepatocytes do

A

remove harmful substances from the blood and break them down into less harmful substances that then re-enter the blood

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9
Q

what is a bile canaliculus

A

tubes which bile is secreted into from hepatocytes which connect up to the bile ducts

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10
Q

what is the function of a kupffer cell

A

removes bacteria and breaks down old red blood cells

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11
Q

what is in the centre of each lobule

A

central vein leading to hepatic vein

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12
Q

what are excess amino acids broken down into

A

ammonia and keto acids

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13
Q

what are the keto acids used for

A

enter the Krebs cycle and respired to give atp or stored as glycogen

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14
Q

what cycle does ammonia enter

A

ornithine cycle

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15
Q

what is the purpose of the ornithine cycle

A

to convert ammonia to urea

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16
Q

what is the removal of amine groups from amino acids called

A

deamination

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17
Q

what is the first step in the ornithine cycle

A

ammonia is combined with carbon dioxide which reacts with ornithine to get citrulline

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18
Q

what is the second step of the ornithine cycle

A

ammonia is added to citrulline to make arginine. water is lost

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19
Q

what is the third step of the ornithine cycle

A

water is added to arginine to regenerate ornithine and produce urea

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20
Q

how does the liver remove alcohol

A

breaks it down into ethanal and then acetic acid which is less harmful

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21
Q

name 2 substances that the liver breaks down

A

alcohol, paracetamol and insulin

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22
Q

what does excess alcohol do to the liver

A

cirrhosis of the liver (ells die leaving scar tissue blocking blood flow)

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23
Q

what does the liver store

A

glycogen

24
Q

what blood vessel does blood enter the kidney through

A

renal artery

25
Q

which is the darker thick layer of the kidney

A

medulla

26
Q

what is the outer light layer of the kidney

A

cortex

27
Q

what tube does urea leave kidney via

A

ureter

28
Q

what is the pelvis of the kidney

A

area at the centre of the kidney where urine collects to be filtered into ureter

29
Q

where does ultrafiltration take pace

A

glomerulus and bowman’s capsule

30
Q

what causes liquid and small molecules to filter out of capillaries.

A

the afferent capillary has a wider lumen then the efferent which causes there to be a high pressure pushing out the liquids and small molecules.

31
Q

what is the basement membrane

A

stops larger molecules leaving the capillaries

32
Q

what are podocytes

A

cells that are wrapped around the bowman’s capsule and allow filtration

33
Q

what is selective reabsorption

A

when useful substances are reabsorbed back into the blood

34
Q

where does selective reabsorption take place

A

proximal convoluted tubule

35
Q

how does selective reabsorption take place

A
  1. sodium ions are co transported into cells of the PCT wall with glucose and amino acids
  2. glucose and amino acids can enter blood via diffusion down a concentration gradient, sodium ions are actively transported into blood
  3. water moves by osmosis to the blood from the PCT
36
Q

what mechanism is used to reabsorb water in the loop of Henle

A

counter current multiplier

37
Q

how is water reabsorbed in the loop of henle

A
  1. sodium and chloride ions are actively transported out of the ascending limb which decreases the water potential in the medulla
  2. water diffuses out the descending limb via osmosis
    3some ions are reabsorbed into the descending limb to create a cycle
38
Q

which limb of the loop of Henle is impermeable to water

A

ascending limb

39
Q

what hormone controls water reabsorption

A

ADH (antidiuretic hormone)

40
Q

what gland releases ADH

A

posterior pituitary gland

41
Q

what detects changes in water potential

A

osmoreceptors in the hypothalamus

42
Q

what happens when ADH binds to receptors on collecting duct membrane

A
  1. stimulates CAMP production which stimulates vesicles containing aquaporins to bind with membrane
    2 water can filter out of the aquaporin channels
43
Q

is there more or less concentrated urine when more ADH is produced

A

more concentrated

44
Q

how can we detect kidney failure

A

glomerular filtration rate is low

45
Q

what can cause kidney failure

A

high blood pressure and infections

46
Q

what problems does kidney failure cause

A

build up of waste, fluid accumulation, imbalance of electrolytes and anaemia

47
Q

what is haemodialysis

A

patients blood is passed through a dialysis machine. waste filters out into dialysis fluid. anti clotting agents are added

48
Q

advantages of haemodialysis

A

only need to do it a few times a week

49
Q

what is peritoneal dialysis

A

dialysis fluid enters abdominal cavity and waste diffuses across peritoneum.

50
Q

advantages of peritoneal dialysis

A

can be done at home

51
Q

what is a kidney transplant

A

a new kidney is implanted to replace the damaged one

52
Q

advantages of transplant

A

cheaper than continual dialysis and more convenient

53
Q

disadvantages of transplant

A

can be rejected by immune system and risks of infection during surgery

54
Q

how is urine used in pregnancy tests

A
  1. monoclonal antibodies attached to a dye bind to hCG in urine of pregnant woman.
  2. urine moves up to test strip where immobilised antibodies are fixed. hCG binds to them and dye is concentrated showing a positive result
55
Q

what is the other method of chemical testing of urine

A

gas chromatography and mass spectrometry

56
Q

what animals would have a longer loop of henle

A

ones living in dry environments because they will need to reabsorb more water

Biology A level (13 decks)

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