Excretion

Question 1

excretion

Answer 1

the removal of metabolic waste from the body

Question 2

excretory products

Answer 2

carbon dioxide from respiration, nitrogen-containing compounds (urea), other compounds (bile)

Question 3

importance of excretion

Answer 3

to ensure they don’t build up to toxic level, altering pH, acting as inhibitors on enzyme activity and preventing normal metabolism

Question 4

how liver stores sugar

Answer 4

in the form of glycogen in granules in the cytoplasm of hepatocytes, broken down when required

Question 5

how toxins can be rendered harmless

Answer 5

oxidation, reduction, methylation or combination with another molecule

Question 6

enzymes in liver cells that render toxins harmless

Answer 6

catalase- converts hydrogen peroxide –> oxygen + water
cytochrome P450- break down (metabolise) drugs, cause side effects of medicinal drugs, involved in other metabolic reactions (ETC)

Question 7

detoxification of alcohol

Answer 7

ethanol broken down in hepatocytes to acetyl CoA + reduced NAD for respiration

Question 8

what if the liver has to detoxify too much alcohol

Answer 8

uses up stores of NAD so not enough left for fatty acids –> converted back to lipids –> stored in hepatocytes –> ‘fatty liver’ and hepatitis/cirrhosis

Question 9

osmoregulation

Answer 9

the control of water potential in the body by controlling the levels of salt and water- prevent water entering cells causing lysis/leaving causing crenation

Question 10

how to assess kidney function

Answer 10

estimating the glomerular filtration rate (GFR)- a measure of how much fluid passes into the nephrons per minute (normal is 90-120cm3min-1)

Question 11

causes of kidney failure

Answer 11

diabetes mellitus, heart disease, hypertension, infection

Question 12

renal dialysis

Answer 12

waste products, excess fluid and mineral ions are removed from the blood by passing over a partially permeable dialysis membrane, allowing exchange of substances with the dialysis fluid

Question 13

how renal dialysis maintains the correct concentrations of substances

Answer 13

in excess in the blood -> diffuses into dialysis fluid

if too low concentration -> diffuses into blood from fluid

Question 14

metabolic waste

Answer 14

a substance produced in excess by the metabolic processes in the cells

Question 15

ornithine cycle

Answer 15

a series of biochemical reactions that convert ammonia to urea

Question 16

nephron

Answer 16

functional unit of the kidney

Question 17

ultrafiltration

Answer 17

filtration of the blood at molecular level under pressure

Question 18

ADH

Answer 18

a hormone that controls the permeability of the collecting duct walls

Question 19

osmoreceptor

Answer 19

a sensory receptor that detects changes in water potential

Question 20

glomerular filtration rate (GFR)

Answer 20

the rate at which fluid enters the nephrons

Question 21

monoclonal antibodies

Answer 21

made from one type of cell- they are specific to one complementary molecule

Question 22

what is renal dialysis

Answer 22

a mechanism used to artificially regulate the concentrations of solutes in the blood

Question 23

Kupffer cells

Answer 23

specialised macrophages that move within sinusoids, breakdown and recycle old RBCs

Question 24

single layer of live cells

Answer 24

remove or return substances to blood

Question 25

bile

Answer 25

made in liver cells and released into bile canaliculi which join to form bile duct and transported to gall bladder

Question 26

metabolic functions of hepatocytes

Answer 26

protein, cholesterol, bile salts synthesis
storage of carbs
detoxification