excretion - the liver

Question 1

what is secretion

Answer 1

production + release of hormones, enzymes, neurotransmitters from cells

Question 2

give 2 examples of a hormone

Answer 2

• insulin
• adrenaline

Question 3

give 2 examples enzymes

Answer 3

• amylase
• protease

Question 4

give 2 examples of neurotransmitters

Answer 4

• ACH
• noradrenaline

Question 5

what is egestion

Answer 5

• removal of undigested food from the body in faeces

Question 6

excretion

Answer 6

• removal of metabolic waste from the body.

Question 7

what is the importance of removing carbon dioxide

Answer 7

• excess carbon dioxide is toxic
• majority of carbon dioxide is carried as hydrogen carbonate ions

Question 8

what is the effect of adrenaline on liver cells

Answer 8

Adrenaline is released from the adrenal gland in times of stress. it causes glycogenolysis to increase blood sugar levels.

Question 9

what happens if blood sugar levels are to low

Answer 9

• alpha cells secrete glucagon from islets of Langerhans
• glucagon binds to couped receptors in the G protein coupled receptors in teh cell surface membrane.
• leads to the activation of enzymes, causing the hydrolysis of glycogen to glucose (glycogenolysis)
• once blood sugar levels increase glucagon stops being released

Question 10

what happens if blood sugar levels are to high

Answer 10

• beta cells secrete insulin into the blood from the islet of Langerhans
• insulin binds to tyrosine kinase receptors in the cell surface membrane of hepatocytes
• causes glucose transports to be inserted into the membrane.
• hepatocytes take up glucose and respire it in glycolysis
• they convert it to glycogen (glycogenesis)
• this lowers blood glucose levels and so insulin is not secreted anymore.

Question 11

what are hepatocytes

Answer 11

the major parenchymal cells in the liver.

Question 12

what is deamination

Answer 12

the removal of an amine group (NH2)

Question 13

describe the ornithine cycle

Answer 13

• ammonia is then converted to urea and urea is less soluble and less toxic than ammonia so it needs less water for removal. fish just excrete ammonia.
• ornithine acts as a carrier molecule on which urea is assembled. Ornithine is regenerated at the end of the cycle and can be reused in the next cycle.

Question 14

describe the synthesis of red blood cells in the foetus

Answer 14

• stem cells divide by mitosis
• they leave the cell cycle and enter G0
• they differentiate and change shape to produce Haemoglobin
• the lose their nucleus + mitochondria.

Question 15

describe the destruction of red blood cells

Answer 15

• haemoglobin is broken down by bile salts in to bile and the rest is excreted in the faeces.

Question 16

what is glucagon

Answer 16

a hormone that causes the breakdown of glycogen to glucose, producing an increase in the blood glucose concentration.

Question 17

what is gluconeogenisis

Answer 17

the rocess, where amino acids and fats are converted into additional glucose.

Question 18

what is glycogenesis

Answer 18

the conversion of glucose to glycogen for storage

Question 19

what is glycogenolysis

Answer 19

glycogen converted to glucose by phosphorylase A

Question 20

what is the function of the Kupffer cells

Answer 20

specialised phagocytes
- rapidly remove bacteria
- destroy old red blood cells-> bile salts -> bile