Topic 13 (Excretion)

Question 1

What are some metabolic waste products?

Answer 1

Carbon dioxide - a product of aerobic
respiration of glucose.
Urea - a waste product from the breakdown
of proteins.
Mineral ions - excess ions in the blood can be harmful as they make the blood plasma more concentrated.
Water - excess water in the body is harmful as it causes the cell to swell and burst.

Question 2

Define the term deamination.

Answer 2

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

Question 3

What is excretion?

Answer 3

The removal of metabolic waste products, toxic substances and substances that are in excess of the body’s requirements.

Answer 4

Carbon dioxide - Lungs - Gas in expired air
Excess salts or ions - Kidneys, Skin - Constituent of urine, Constituent of sweat
Excess water - Kidneys, Skin - Constituent of urine, Constituent of sweat
Urea - Kidneys, Skin - Constituent of urine, Constituent (traces) in sweat

Question 5

Why is excretion important?

Answer 5

It prevents the build up of harmful or toxic substances in our bodies.

Question 6

What makes up the human urinary system?

Answer 6

Kidneys, renal artery, renal vein, inferior vena cava, aorta, ureter, urinary bladder, urethra.

Question 7

Describe the structure of a kidney.

Answer 7

Slide 8.

Question 8

What is the structure of a nephron?

Answer 8

Slide 9.

Question 9

How is urine formed?

Answer 9

Filtration - filtration is the process where small molecules are filtered out of the blood by the glomerulus into the renal capsule.
Reabsorption - as filtrate passes along the nephron,
useful substances are reabsorbed into the surrounding blood capillaries.
Only substances that the body needs
are reabsorbed.