Excretion

Question 1

Urea

Answer 1

urea is formed in the liver from excess amino acids

Question 2

Role of the liver in the assimilation of amino acids by converting them to proteins, including plasma proteins, e.g. fibrinogen

Answer 2

Amino acids, cannot be stored in the body, thus excess amino acids which cannot be used by the body are removed from

Question 3

Co2

Answer 3

carbon dioxide is excreted through the lungs

Question 4

Deamination

Answer 4

the removal of the nitrogen-containing part of amino acids to form urea

Question 5

excess water and salts

Answer 5

kidneys excrete urea and excess water and salts, Filtered by the blood from kidneys and excreted as urine.

Question 6

what affects volume and concentration of urine produced

Answer 6

affected by water intake, temperature and exercise

Question 7

structure of the kidney

Answer 7

cortex: Outer region of the kidney, contains nephrons
medulla: Inner region of the kidney
ureter: Tubes that transports urine from the kidney to the bladder, where it is stored before excreted from the body.
- Renal artery: inside the kidney
- Renal vein: Outside the kidney

Question 8

structure and functioning of a kidney tubule

Answer 8

• the role of the glomerulus (etwork of small blood vessels (capillaries) tangled together): the filtration from the blood of water, glucose, urea and salts
• role of the tubule: the reabsorption of all of the glucose, most of the water and some salts back into the blood, leading to the concentration of urea in the urine as well as loss of excess water and salts (details of these processes are not required)

Question 9

Explain term Dialysis, in terms of salt balance

Answer 9

Dialysis is artificial system of removing urea from the blood, maintenance of glucose concentration.

Question 10

use of dialysis in kidney machines

Answer 10

• Help excrete urea from the body

- Filters and purifies blood

Question 11

Advantages and disadvantages of

kidney transplants, compared with dialysis

Answer 11

Advantages

• The patients can return to a normal lifestyle – dialysis may require a lengthy session in hospital, 3 times a week, leaving the patient very tired after each session.
• Dialysis machines are expensive to buy and maintain.
• There is no restricted diet

Disadvantages

• Transplants require a suitable donor. The donor needs to be a person who is prepared to donate a healthy kidney (we can survive with one kidney)
• There is a risk of rejection of the donors kidney – immunosuppressive drugs have to be used, which stops WBC working efficiently, thus person likely to suffer from infectious diseases.
• The operation is very expensive.