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Biology A Level > Excretion (only key points so refer to notes) > Flashcards

Excretion (only key points so refer to notes) Flashcards

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1
Q

Excretion

A

removal of metabolic waste from the body

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2
Q

metabolic waste

A

substances produced in excess by metabolic processes in cells

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3
Q

main excretory products

A

carbon dioxide from respiration
nitrogen containing compounds like urea
bile pigments found in faeces

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4
Q

__________ is a substance that passes into _____ for excretion with faeces.

A

bilirubin

bile

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5
Q

what does the liver do?

A

converts excess amino acids to urea

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6
Q

what is the breakdown of amino acids called?

A

deamination

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7
Q

what substances does the skin excrete in sweat?

A

salts, urea, water, uric acid, ammonia

but water and salts are more to do with homeostasis not excretory products

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8
Q

how does carbon dioxide form hydrogen ion?

A

carbon dioxide + water ——> carbonic acid

carbonic acid dissociates to hydrogen ions and hydrogencarbonate ions

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9
Q

What do hydrogen ions affect?

what other substances reduce oxygen transport?

A

pH - bonds - haemoglobin shape - affinity for oxygen - oxygen transport
structure of other proteins that help transport substances
haemoglobinic acid
carbamonihaemoglobin

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10
Q

What does the body do to deal with H ions?

A

small change in pH - hydrogen ions detected by respiratory centre in medulla oblongata of brain - increases breathing rate to remove more carbon dioxide

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11
Q

respiratory acidosis

A

change in blood pressure by diseases, conditions that affect lungs

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12
Q

Briefly, what happens to excess amino acids?

A

toxic amino group removed (deamination)
amino group forms ammonia (very soluble, highly toxic)
amino acid + oxygen —–> ammonia + keto acid

ammonia + carbon dioxide —–> urea (less soluble, less toxic) + water
urea transported to kidneys for excretion

keto acid used in respiration or converted to carbohydrate/fat for storage

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13
Q

what does the hepatic artery do?
what does the hepatic portal vein do and what’s in the blood that is carries?
hepatic vein?

A

supplies oxygenated blood from aorta to liver for respiration

deoxygenated blood from digestive system, rich in products of digestion, blood contains toxic compounds absorbed from intestine so concentration of substances needs adjusting

blood leaves to vena cava to normal body circulation

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14
Q

Bile duct

bile function?

A

carries bile to gall bladder to be stored until required for digestion of fats in small intestine
bile contains excretory products - bile pigments like bilirubin that leaves in faeces

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15
Q

liver is divided into ________ which divided into __________.

A

lobes

lobules

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16
Q

inter-lobular vessels

A

smaller vessels from hepatic artery/hepatic portal vein

run between and parallel to lobules

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17
Q

what happens when blood enters lobules from inter-lobular vessels?

A

blood mixed passes to sinusoid (close contact with liver cells, they line it, remove/return substances from/to blood)

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18
Q

Kupffer cells

A

specialised macrophages that breakdown and recycle RBC

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19
Q

what is the product of haemoglobin breakdown?

A

bilirubin

20
Q

features of hepatocytes

A

simple cuboidal shape
microvilli on surface
cytoplasm dense (many metabolic functions)

21
Q

metabolic functions of liver

A

controls blood glucose levels, amino acid levels, lipid levels

synthesises bile, plasma proteins, cholesterol, RBC in fetus

stores vitamins, iron, glycogen

breaks down hormones

detoxifies alcohol and drugs

destroys RBC

22
Q

how are toxins rendered harmless?

A

oxidation, reduction, methylation, combine with molecules

23
Q

what does catalase do?

A

catalyses breakdown of hydrogen peroxide to oxygen and water

24
Q

what does cytochrome P450 do?

A

breakdown drugs and in electron transport (respiration)

role in metabolising drugs can interfere with other metabolic roles which causes side effects

25
Q

fatty liver

A

liver detoxify lots of alcohol, uses NAD so less to breakdown fatty acids so converted back to lipids and stored as fats in hepatocytes

26
Q

renal artery

renal vein

A

supplies kidney with blood

drained out

27
Q

nephrons

A

functional unit of kidney

tiny tubules

28
Q

glomerulus

A

knot of capillaries in Bowman’s capsule

29
Q

fluid from the blood passes into the Bowman’s capsule by___________________ which is…….

A

ultrafiltration

filtration of blood at molecular level under pressure

30
Q

3 layers between blood in capillary and lumen of Bowman’s capsule

A

endothelium of capillary
basement membrane
epithelial cells of Bowman’s capsule (podocytes)

31
Q

endothelium of capillary

A

narrow gaps between cells of endothelium of capillary walls

cells contain pores called fenestrations where blood plasma can pass out capillary

32
Q

basement membrane

A

fine mesh of collagen fibres and glycoproteins

prevents molecules with relative molecular mass greater than 69000 passing

33
Q

podocytes

A

finger-like projections (major processes) on each are minor/foot processes
hold cells away from endothelium of capillary
ensure gaps between cells so fluid can pass between to lumen on capsule

34
Q

afferent arteriole is _______ than the efferent so ___________________

A

wider
ensures blood in capillaries of glomerulus maintains higher pressure than in Bowman’s capsule
pressure difference pushes fluid from blood to lumen

35
Q

what happens at the proximal convoluted tubule?

A

selective reabsorption of 85%

reabsorb all sugars, most mineral ions, some water

36
Q

how are cells lining the proximal convoluted tubule specialised?

A

cell surface membrane in contact with tubule fluid, highly folded (microvilli) so increase SA

membrane contains cotransporter proteins that transport glucose/amino acids in association with sodium ions from tubule into cells lining it.

opposite membrane close to tissue fluid and blood capillaries is also highly folded to increase SA

this membrane contains sodium/potassium pump to pump sodium ions out cell and potassium in

cytoplasm dense with many mitochondria

37
Q

how does selective reabsorption occur?

A

sodium pumped out cells lining tubule so conc. decreases in cells and creates gradient
sodium ions from tubule associated with glucose/amino acids diffuse to cells through cotransporter proteins
water potential decreases in cells so water from tubule to cell by osmosis
glucose/amino acids diffuse into blood

38
Q

osmoregulation

A

control of water potential in the body

39
Q

ADH

A

antidiuretic hormone

40
Q

invaginates

A

membrane folds inwards when low levels of ADH

so creates new vesicles that remove aquaporins from membrane

41
Q

adjusting ADH

A

water potential low so osmoreceptors in hypothalamus lose water by osmosis and shrink, activate neurosecretory cells (nerve cells) in hypothalamus
neurosecretory cells produce and release ADH, moves down axon to terminal bulb in posterior pituitary gland
stored in vesicles
when cells stimulated, AP down axon and release ADH by exocytosis
ADH to capillaries act on collecting duct

42
Q

glomerular filtration rate

A

rate fluid enters nephron

43
Q

renal dialysis

A

artificially regulate concentrations of solutes in blood

blood passes over partially permeable dialysis membrane and exchange occurs between blood and dialysis fluid

44
Q

haemodialysis

A 
blood from artery/vein pass into machine
artificial dialysis membrane shaped into capillaries
heparin added to avoid clotting
counter current flow
blood returned to body via vein
45
Q

peritoneal dialysis

A

dialysis membrane in own abdominal membrane (peritoneum)

permanent tube in abdomen, dialysis solution poured through, used solution drained out

46
Q

hCG

A

human chorionic gonadotrophin

47
Q

pregnancy tests use…..

A

monoclonal antibodies (made from 1 cell, specific to 1 molecule)

Biology A Level (28 decks)

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