Excretion

Question 1

Excretion

Answer 1

The removal of metabolic waste and excess and toxic materials

Question 2

Excretory products of lungs

Answer 2

CO2 + water vapour

Question 3

Excretory products of skin

Answer 3

Sweat (salt + water)

Question 4

Excretory products of kidney

Answer 4

Urine (urea, water, ions)

Question 5

Osmoregulation

Answer 5

Maintain a constant water concentration of the blood, brain and kidney

Question 6

How can kidneys change osmoregulation

Answer 6

Depending on the ion and water concentration of the blood

Question 7

Consequence of high water concentration of blood

Answer 7

Too much water (hypotonic)
Water enters cells by osmosis
Cells swell and burst
CELL LYSIS

Question 8

Consequences of high salt concentration of blood

Answer 8

Too little water (hypertonic)
Water leaves cells by osmosis
Cells shrivel
CRENATION

Question 9

Leaves excretory products

Answer 9

Day: oxygen
(Photosynthesis > respiration)
Night: CO2
(Respiration > photosynthesis)

Question 10

Role of kidney

Answer 10

Filter blood and reabsorb useful substances back into the blood
Osmoregulation
Excretion

Question 11

Ultrafiltration

Answer 11

Blood arrives at high pressure
Small molecules (water, urea, glucose + salts) are forced out of the blood into bowman’s capsule
Large molecules (protein + RBC’s) remain in blood

Question 12

Selective réabsorption

Answer 12

All- glucose (diffusion + active transport)
Most- salts (diffusion)
Some- water (osmosis)
Convoluted tubules

Question 13

What hormone controls water reabsorption

Answer 13

ADH- released from pituitary glands in the brain

Question 14

What does ADH do

Answer 14

Low H2O conc -> more ADH -> increasing permeability -> more H20 reabsorbed

High H2O conc -> less ADH -> decreasing permeability-> less H2O reabsorbed

Question 15

Why is protein not found in urine of a healthy person

Answer 15

Too large to pass through from the glomerulus into the bowman’s capsule

Question 16

Why is glucose not found in the urine of a healthy person

Answer 16

All glucose Is reabsorbed back in the blood at the convoluted tubules

Question 17

What is contained in urine

Answer 17

Urea, excess salt + water

Question 18

Conc + volume of urine on a hot day

Answer 18

Sweat -> low H2O conc -> more ADH -> collecting duct more permeable -> more H2O reabsorbed -> more concentrated and less urine

Question 19

Diabetes

Answer 19

Glucose in urine
Daily injections of hormone insulin

Question 20

Urinary tract infection (UTI)

Answer 20

Protein in urine
Antibiotics

Question 21

Renal failure

Answer 21

Protein and glucose in urine
Dialysis or kidney transplant

Question 22

Glucose test

Answer 22

Benedict’s solution
Heat in boiling water bath for 5 mins
Blue -> brick red

Question 23

Protein test

Answer 23

Biuret solution
Spotting tile
Blue -> lilac

Question 24

Substances patients on dialysis need to remove from blood

Answer 24

Urea + mineral ions
They are toxic and otherwise the salt and water balance of your body is lost

Question 25

Substances which are at the same conc in dialysis fluid and normal level in blood

Answer 25

Glucose + mineral ions
So they don’t lose these useful substance from the blood

Question 26

Substances that dialysis fluid doesn’t contain at the start

Answer 26

Urea
So there is a strong conc gradient from blood to fluid for this substancr

Question 27

Why is constant circulation of dialysis fluid important

Answer 27

So that the conc gradient is high so waste substances diffuse out

Question 28

Kidney transplant advantages and disadvantages

Answer 28

Don’t have to follow a strict diet
Have to take medicine everyday of you life incase kidney is rejected

Question 29

Dialysis advantage and disadvantages

Answer 29

It is more readily available than donor organs
Regular, long sessions connected to a dialysis machine