Chapter 15.4 - Excretion and the Liver

Question 1

What is excretion?

Answer 1

removal of waste products of metabolism from the body

Question 2

Why is excretion important?

Answer 2

if the toxic waste products build up they are toxic to the body

Question 3

What does sweat contain?

Answer 3

• water
• salt
• uric acid

Question 4

What are the main metabolic wast products in the body?

Answer 4

• carbon dioxide
• bile pigments
• nitrogenous waste products (urea)
• sweat

Question 5

How is carbon dioxide formed and where is it excreted from?

Answer 5

waste products of respiration

Question 6

How are bile products formed an how are they excreted?

Answer 6

• breakown of haemaglobin from the blood in the liver

- excreted in bile from the liver into small intestine via gall bladder and bile duct

Question 7

How are nitrogenous waste products (urea) formed and how are they excreted?

Answer 7

-breakdown of excess amino acids by the liver
- urea excreted by the kidneys as urine
other examples birds and insects release uric acid
fish produce ammonia

Question 8

what are the three functions of the liver regarding homeostasis?

Answer 8

• can convert glucose into glycogen and vice versa (hepatic portal vein can carry glucose (product of digestion) from the intestines to the sinusoid) (hepatic artery can transport glucose from pancreas to sinusoid)
• Deamination (removal of amine group, converted into ammonia, then urea - less toxic chemical, removed from the kidneys as urine)the rest of the amine group can be used in respiration for atp production
• detoxification ie alcohol dehydrogenase (converts ethanol into ethanal then ethanoate, which is safer chemical)

Question 9

Why does deamination take place?

Answer 9

• body cant store protein molecules

- cant excrete it as it would go to waste