3.6.4.2 - Control of blood glucose conc.

Question 1

What is negative feedback ?

Answer 1

When any deviation from the normal values are restored to their normal values.
- Minimises deviations from normal set points.

Question 2

Key examples of conditions controlled by neg. feedback

Answer 2

• Body temp
• Blood pH ( too high or low - disrupts active site shape)
• BG conc. - affects osmosis

Question 3

what does the pancreas do?
What does it contain to do so?

Answer 3

Detects changes in BG levels
Contains endocrine cells in the Islets of Langerhans - release insulin and glucagon

Question 4

Neg feedback loop (increase)

Answer 4

• BG levels rise
• beta cells detect and release insulin
• Liver cells - more permeable to glucose and enzymes = activated to conevrt glucose to glycogen
• Glucose is removed from blood and stored as glycogen in cells

Question 5

Neg feedback (decrease)

Answer 5

• BG levels decrease
• detected by alpha cells which release glucagon
  (adrenal gland releases adrenaline)
• 2nd messenger model occurs to activate enzymes to hydrolyse glycogen
• Glycogen is hydrolysed to glucose and more glucose = back in blood