Ch. 8 Homeostasis of Blood Sugar

Question 1

where is excess glucose stored

Answer 1

as glycogen in liver muscle and fat

Question 2

what organs secrete hormones that affect good sugar

Answer 2

pancreas and adrenal glands

Question 3

what is glycogenesis and what stimulates it

Answer 3

Glucose > glycogen

Stimulated by insulin (pancreas)

Question 4

what is glycogenolysisand what stimulates it

Answer 4

Glycogen > glucose

Stimulated by glucagon (pancreas)

Question 5

what is gluconeogenesis and what stimulates it

Answer 5

Fat > glucose
Amino acid > glucose
Glucagon
Glucocorticoids

Question 6

What 4 processes can occur when glucose reaches the liver from hepatic portal vein

Answer 6

1. Glucose used to provide energy for liver functioning
2. Converted into glycogen for storage
3. Continue to circulate body (used in cells as source of energy)
4. Excess glucose (not needed to maintain blood sugar level and tissue glycogen level) converted into fat for long term storage

Question 7

What are the three purposes of glycogenolysis in the liver

Answer 7

o Maintain glucose levels
o Supply energy for liver
o Short term energy supply (if need more energy, uses fat storage)

Question 8

What is the purpose of glycogenolysis in skeletal muscles

Answer 8

o Provide glucose required for muscle activity

Question 9

What secretes hormones in the pancreas

Answer 9

islets of langerhans

Question 10

what are the two cell types in the isles of langehan and what do they secrete

Answer 10

• Contains two types of cells:
  o Alpha cells= secretes glucagon
  o Beta cells= secrete insulin

Question 11

What does beta cells secrete and what overall does it do

Answer 11

• Insulin from beta cells decrease blood sugar levels

Question 12

How does insulin decrease level of blood sugar (4)

Answer 12

1. Increase transport/consumption of glucose by cells
2. Promotes glycogenesis
3. Promotes fat storage
4. Promotes protein synthesis

Question 13

Expain the negative feedback of insulin

Answer 13

o Blood sugar rises above normal> chemical sensors in beta cells of islets stimulate those cells to secrete insulin> level of blood sugar decrease // cells no longer stimulated> production is reduced

Question 14

What does alpha cells secrete and what overall does it do

Answer 14

• Glucagon from alpha cells increase blood sugar levels

Question 15

what are the three ways glucagon increases blood glucose level

Answer 15

1. Stimulating glycogenolysis
2. Stimulating gluconeogenesis
3. Mild stimulating effect on protein breakdown

Question 16

explain negative feedback of glucagon

Answer 16

o Blood sugar falls> chemical sensors in alpha cells of islets stimulate those cells to secrete glucagon > blood sugar increases = cells no longer stimulated > production reduced

Question 17

What does the adrenal cortex secrete and what stimulates it

Answer 17

• Secretes glucocorticoids (e.g. cortisol)

o Stimulated by adrenocorticotropic hormone (ACTH) from anterior

Question 18

how does cortisol increase blood glucose

Answer 18

1. Glycogenolysis- Regulate carbohydrate metabolism by making sure enough energy provided to cells
2. Gluconeogenesis- increase rate at which amino acids are removed from cells (mainly muscles) and transported to liver > converted to glucose
3. Promote mobilisation of fatty acids from adipose tissue, allowing muscle cells to shift from glucose to fatty acids for much of their metabolic energy

Question 19

what does the adrenal medulla secrete and what does it do

Answer 19

• Secretes epinephrine and norepinephrine

1. Glycogenolysis: stimulate breakdown of glycogen