excretion⚠️

Question 1

suggest why a high intake of protein in the diet will be likely to result in a high concentration of urea in urine

Answer 1

• high protein means high concentration of amino acids
• amino acids cannot be stored
• amino acids deaminated
• ammonia enters orinthine cycle
• increased blood concentration of urea

Question 2

what hormone is tested for in a pregnant test

Answer 2

human chorionic gonadotropin

Question 3

name of cup shaped structure under glomerulus

Answer 3

bowmans capsule

Question 4

explain how the glomerulus is able to perform its function

Answer 4

• afferent arteriole is wider than efferent arteriole
• build up of hydrostatic pressure
• endothelium of capillary walls has small pores
• this all allows ultrafiltration

Question 5

suggest the effects of complete kidney failure on the composition of the blood

Answer 5

• increase in urea
• increase in salts
• increase in water

Question 6

features of bowman’s capsule that allows it to function efficiently

Answer 6

• basement membrane stops removal of large molecules

- podocytes have projections which ensure gaps to allow passage of substances

Question 7

nephritis is a condition in which the tissue of the glomerulus and proximal convoluted tubule becomes inflamed and damaged.

suggest two differences in the composition of the urine of a person with nephritis when compared to the urine of a person with healthy kidneys.

Answer 7

• proteins present
• glucose present
• blood cells present

Question 8

how a channel protein ensure no positive ions go through

Answer 8

-channel has positive charge which repels positive ions

Question 9

which cells produce ADH

Answer 9

-nerve cells= osmoreceptors

Question 10

how is change of water potential of blood detected

Answer 10

• blood flows through hypothalamus

- osmoreceptors

Question 11

where is ADH secreted from

Answer 11

posterior pituitary gland

Question 12

ADH acts on the cells of …

Answer 12

the collecting duct

Question 13

name of channel proteins that ADH causes to insert themselves into plasma membrane

Answer 13

aquaporins

Question 14

suggest where ADH is removed from the blood and describe what then happens to the ADH molecule

Answer 14

• in the liver (as a protein)
• hydrolysis
• deamination
• orinthine cycle
• in the kidneys(as a small molecule)
• ultrafiltered from the blood as it is a small molecule
• not reabsorbed
• excreted

Question 15

what is added to ammonia at the start of the ornithine cycle

Answer 15

co2 and ornithine

Question 16

a pregnancy testing kit contains a testing ‘stick’ to detect a hormone in the urine

explain how the stick detects this pregnancy hormone

Answer 16

• testing for hCG
• hormone small so can pass from blood into filtrate
• immobilised antibodies on stick
• antibodies attached to marker
• hormone complementary to antibody so binds
• coloured line appears

Question 17

name the tissue that lines the proximal convoluted tubule

Answer 17

epithelium

Question 18

name the structures that line the proximal convoluted tubule

Answer 18

microvilli

Question 19

Some of the changes observed between the glomerular filtrate and the urine are as a result of activity in the proximal convoluted tubule.

explain how these observed changes in concentration are brought about by the proximal convoluted tubule.

Answer 19

• selective reabsorption
• of glucose and amino acids
• by facilitated diffusion
• water follows by osmosis so concentration of ions and urea increases

Question 20

blood from which blood vessel enters dialysis machine

Answer 20

artery

Question 21

blood from which vessel leaves dialysis machine

Answer 21

vein

Question 22

why is it necessary to add anticoagulant to blood entering dialysis

Answer 22

to prevent blood clots during dialysis

Question 23

why does the dialysis fluid used in peritoneal dialysis contain dextrose solution rather than water alone?

Answer 23

• dextrose reduces wp of dialysis fluid
• kidney function is to remove excess water from blood
• if it was water alone then water would enter cells by osmosis causing them to burst

Question 24

where in the nephron is glucose selectively reabsorbed into the blood capillaries

Answer 24

proximal convoluted tubule

Question 25

which regions of the nephron are present in the cortex

Answer 25

- proximal convoluted tubule - glomerulus - distal convoluted tubule - top of collecting duct

Question 26

where are podocytes present

Answer 26

lining the bowmans capsule

Question 27

explain how the longer loop of Henle is able to assist the desert kangaroo rat in preventing excessive water loss

Answer 27

- more ions pumped into medulla - builds up greater wp gradient - allows more water to be reabsorbed from collecting duct

Question 28

state type of drug that can be misused in body building

Answer 28

anabolic steroids

Question 29

explain changes in fluid composition from blood to urine

Answer 29

- large molecules cannot enter filtrate - basement membrane prevents large molecules and erythrocytes reaching Bowmans capsule - all glucose and amino acids reabsorbed at proximal convoluted tubule - some ions reabsorbed - urea concentration increases between filtrate and urine due to movement of urea into tubule

Question 30

what is absorbed in the proximal convoluted tubule into what are these absorbed

Answer 30

- most of the water - some salts -into blood capillaries

Question 31

in what part of the nephron are walls impermeable to water

Answer 31

-ascending limb of loop of henle

Question 32

in what part of the nephron is glucose reabsorbed into blood

Answer 32

proximal convoluted tubule

Question 33

on what part of the nephron does ADH act

Answer 33

-collecting duct walls

Question 34

what part of the nephron contains podocytes

Answer 34

bowmans capsule

Question 35

where in the nephron is most water reabsorbed into blood

Answer 35

proximal convoluted tubule

Question 36

explain the role of the loop of Henle in the production of urine

Answer 36

- role of loop of henle is to cause decrease in wp in medulla - in ascending limb, active transport of solutes outwards - walls of descending limb are permeable to water - water removed from descending limb - wp of tissues surrounding collecting duct is lower than fluid inside - water removed from filtrate in collecting duct

Question 37

function of microvilli in PCT

Answer 37

increases SA for reabsorption

Question 38

does DCT or PCT have higher urea concentration and why

Answer 38

DCT as water is removed earlier in nephron