Excretion (only key points so refer to notes)

Question 1

Excretion

Answer 1

removal of metabolic waste from the body

Question 2

metabolic waste

Answer 2

substances produced in excess by metabolic processes in cells

Question 3

main excretory products

Answer 3

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

Question 4

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

Answer 4

bilirubin

bile

Question 5

what does the liver do?

Answer 5

converts excess amino acids to urea

Question 6

what is the breakdown of amino acids called?

Answer 6

deamination

Question 7

what substances does the skin excrete in sweat?

Answer 7

salts, urea, water, uric acid, ammonia

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

Question 8

how does carbon dioxide form hydrogen ion?

Answer 8

carbon dioxide + water ——> carbonic acid

carbonic acid dissociates to hydrogen ions and hydrogencarbonate ions

Question 9

What do hydrogen ions affect?

what other substances reduce oxygen transport?

Answer 9

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

Question 10

What does the body do to deal with H ions?

Answer 10

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

Question 11

respiratory acidosis

Answer 11

change in blood pressure by diseases, conditions that affect lungs

Question 12

Briefly, what happens to excess amino acids?

Answer 12

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

Question 13

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

Answer 13

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

Question 14

Bile duct

bile function?

Answer 14

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

Question 15

liver is divided into ________ which divided into __________.

Answer 15

lobes

lobules

Question 16

inter-lobular vessels

Answer 16

smaller vessels from hepatic artery/hepatic portal vein

run between and parallel to lobules

Question 17

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

Answer 17

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

Question 18

Kupffer cells

Answer 18

specialised macrophages that breakdown and recycle RBC

Question 19

what is the product of haemoglobin breakdown?

Answer 19

bilirubin

Question 20

features of hepatocytes

Answer 20

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

Question 21

metabolic functions of liver

Answer 21

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

Question 22

how are toxins rendered harmless?

Answer 22

oxidation, reduction, methylation, combine with molecules

Question 23

what does catalase do?

Answer 23

catalyses breakdown of hydrogen peroxide to oxygen and water

Question 24

what does cytochrome P450 do?

Answer 24

breakdown drugs and in electron transport (respiration)

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

Question 25

fatty liver

Answer 25

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

Question 26

renal artery | renal vein

Answer 26

supplies kidney with blood | drained out

Question 27

nephrons

Answer 27

functional unit of kidney | tiny tubules

Question 28

glomerulus

Answer 28

knot of capillaries in Bowman's capsule

Question 29

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

Answer 29

ultrafiltration | filtration of blood at molecular level under pressure

Question 30

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

Answer 30

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

Question 31

endothelium of capillary

Answer 31

narrow gaps between cells of endothelium of capillary walls | cells contain pores called fenestrations where blood plasma can pass out capillary

Question 32

basement membrane

Answer 32

fine mesh of collagen fibres and glycoproteins | prevents molecules with relative molecular mass greater than 69000 passing

Question 33

podocytes

Answer 33

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

Question 34

afferent arteriole is _______ than the efferent so ___________________

Answer 34

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

Question 35

what happens at the proximal convoluted tubule?

Answer 35

selective reabsorption of 85% | reabsorb all sugars, most mineral ions, some water

Question 36

how are cells lining the proximal convoluted tubule specialised?

Answer 36

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

Question 37

how does selective reabsorption occur?

Answer 37

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

Question 38

osmoregulation

Answer 38

control of water potential in the body

Question 39

ADH

Answer 39

antidiuretic hormone

Question 40

invaginates

Answer 40

membrane folds inwards when low levels of ADH | so creates new vesicles that remove aquaporins from membrane

Question 41

adjusting ADH

Answer 41

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

Question 42

glomerular filtration rate

Answer 42

rate fluid enters nephron

Question 43

renal dialysis

Answer 43

artificially regulate concentrations of solutes in blood | blood passes over partially permeable dialysis membrane and exchange occurs between blood and dialysis fluid

Question 44

haemodialysis

Answer 44

``` 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 ```

Question 45

peritoneal dialysis

Answer 45

dialysis membrane in own abdominal membrane (peritoneum) | permanent tube in abdomen, dialysis solution poured through, used solution drained out

Question 46

hCG

Answer 46

human chorionic gonadotrophin

Question 47

pregnancy tests use.....

Answer 47

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