Kidneys

Question 1

What is a hormone?

Answer 1

A chemical messenger released into the blood by an endocrine gland

Question 2

List as many molecules as you can think of that leave the blood in ultrafiltration

Answer 2

Water, glucose, urea, minerals/salts (Na, K, Cl etc), amino acids, small proteins (e.g. some hormones). Bonus marks for any other small molecules like lactic acid, oxygen, carbon dioxide, ammonia!

Question 3

What tissue type lines capillaries?

Answer 3

Squamous endothelium

Question 4

Name the three layers between the glomerulus and the bowmans capsule

Answer 4

Squamous endothelium, basement membrane, podocytes

Question 5

The pressure from the heart is trying to squeeze filtrate OUT of the blood, what is the correct term for this pressure?

Answer 5

Hydrostatic pressure

Question 6

What pressure draws fluid back into the blood due to water potential differences?

Answer 6

Osmotic pressure

Question 7

What’s the difference between the arteriole going into the glomerulus (afferent) and the one going out (efferent)?

Answer 7

Afferent is wider than efferent

Question 8

Can glucose pass through the basement membrane?

Answer 8

Yes

Question 9

Are large proteins present in the filtrate?

Answer 9

No, they are too large to pass through the basement membrane. If present the basement membrane is damaged

Question 10

Which filtered substances are reabsorbed in the PCT?

Answer 10

Water, glucose, amino acids, minerals/salts

Question 11

Which substances are in human urine?

Answer 11

Urea, water, some other waste materials (e.g. ammonia, uric acid)

Question 12

Define homeostasis

Answer 12

Maintenance of a constant internal environment

Question 13

Give the steps in a flow chart showing negative feedback

Answer 13

Receptor, Coordinator, Effector, Response

Question 14

What are the functions of a kidney?

Answer 14

Filtering the blood and osmoregulation

Question 15

What is the difference between egestion and excretion?

Answer 15

Egestion is the removal of undigested food from the body (faeces) and excretion is the removal of waste made by the body (eg in urine)

Question 16

What happens to excess amino acids?

Answer 16

Deamination in the liver. The amino group is removed to form ammonia then converted to urea, the rest is converted to a keto acid and either respired or stored

Question 17

How are the cells of the PCT adapted for selective reabsorption?

Answer 17

Microvilli and basal channels give large surface area, many mitochondria, tight junctions

Question 18

How are glucose and amino acids reabsorbed from the filtrate into the blood?

Answer 18

Co transport with sodium ions through the cells of the PCT

Question 19

What is the main function of the loop of Henle?

Answer 19

The ascending limb actively transporting ions out of the filtrate into the medulla tissue fluid to lower the water potential.

Question 20

Which parts of the loop of Henle are permeable/impermeable to water?

Answer 20

The descending limb is permeable, the ascending limb is impermeable

Question 21

When the blood water potential is low, what is the receptor, coordinator, effector and response?

Answer 21

It is detected by osmoreceptors in the hypothalamus, ADH is released from the posterior pituitary gland, this travels to the collecting duct, which becomes more permeable to water (smaller volume of more concentrated urine produced)

Question 22

How does antidiuretic hormone make the collecting duct more permeable to water?

Answer 22

It causes more aquaporins to be added to the membrane on the side next to the lumen. These aquaporins are stored in vesicles which fuse with the membrane.

Question 23

Give an advantage of kidney transplant

Answer 23

The patient no longer needs dialysis

Question 24

Give two disadvantages of kidney transplant

Answer 24

There may be a shortage of organs- there must be donors, and the recipient must stay on immunosuppressants for life

Question 25

What are the two types of kidney dialysis?

Answer 25

Haemodialysis and Peritoneal dialysis.

Question 26

Which nitrogenous waste is excreted by birds and why?

Answer 26

Uric acid, because it is less toxic than ammonia and urea so requires less water to dilute it. This means birds lose less water and have to carry less water for flight

Question 27

Which nitrogenous waste is excreted by mammals and why?

Answer 27

Urea, because it is less toxic than ammonia so requires less water to dilute it- good for terrestrial animals

Question 28

Which nitrogenous waste is excreted by fish and why?

Answer 28

Ammonia. It is highly toxic so needs to be diluted by a lot of water for excretion, but this is fine for aquatic animals.

Question 29

What is the relationship between the length of the loop of Henle and the water availability of the environment?

Answer 29

The less water available the longer the Loop of Henle will be