Unit 6: Homeostasis and blood glucose

Question 1

What is homeostasis?

Answer 1

physiological control systems that maintain the internal environment within restricted limits

Question 2

What is homeostasis important to maintain

Answer 2

• stable core temperature
• stable blood pH
• stable blood glucose
• water potential of blood

Question 3

what mechanism does homeostasis rely on

Answer 3

negative feedback

Question 4

what are hormones

Answer 4

secreted by glands which secrete the hormones into the blood

carried in blood plasma

Question 5

What are target cells

Answer 5

cells with receptors complementary to hormones

Question 6

Why does a stable temperature need to be maintained

Answer 6

to provide optimum temp for enzyme activity.
Low temps dont provide sufficient KE for optimum enzyme activity and if temp is too high enzymes denature

Question 7

why does a stable pH need to be maintained

Answer 7

to provide an optimum pH for enzyme activity
extreme changes in pH cause denaturation

Question 8

why does a stable blood glucose concentration need to be maintained

Answer 8

to provide sufficient substrate for respiration to release energy for metabolic processes in the body

Question 9

why does the water potential of blood need to be maintained

Answer 9

so excess water doesnt enter/leave cells causing them to burst/dehydrate/shrivle

Question 10

what is glycogenesis

Answer 10

conversion of glucose to into glycogen

Question 11

what is glycogenolysis

Answer 11

hydrolysis of glycogen into glucose

Question 12

what is gluconeogenesis

Answer 12

conversion of glycerol and amino acids into glucose

Question 13

how is glucose sourced from your diet

Answer 13

by the hydrolysis of carbohydrates (starch) it is then absorbed into the small intestine

Question 14

How is glucose sourced from stores

Answer 14

glycogen is stored in the liver and muscle cells when excess glucose from the diet undergoes glycogenesis

Question 15

How is glucose sourced by making new glucose

Answer 15

from non carbohydrate sources
the liver can make glucose from glycerol and amino acids (gluconeogenisis)

Question 16

What is negative feedback

Answer 16

restores systems to their original level

Question 17

How does the liver maintain blood glucose concentration

Answer 17

converts excess blood glucose into insoluble storage compound glycogen

Question 18

What is insulin

Answer 18

globular protein made of 51 amino acids

Question 19

How does insulin enter the blood

Answer 19

pancreas detects rise in blood glucose and pancreas beta cells secrete insulin

Question 20

How does insulin work when theres an increase in blood glucose

Answer 20

• attaches to receptors on target cells (liver/muscle)
• increases permeability of target cells to glucose by stimulating the inclusion of more specific channel proteins
• allows glucose to enter by diffusion reducing the blood glucose concentrarion

Question 21

How is glucose converted to glycogen (glycogenesis)

Answer 21

Insulin activates enzymes in the liver/muscles that convert glucose into glycogen
- excess glucose is converted to fat when glycogen stores are full

Question 22

How does the pancreas work when blood glucose decreased

Answer 22

• detected by the pancreas and aloha cells secrete glucagon
• glucagon attatches to receptors on target cells and activate enzymes which hydrolyse glycogen into glucose
• glucose is released into blood

Question 23

How does glucagon work when blood glucose decreases?

Answer 23

• glucagon attaches to receptors on target cells and activates enzymes which hydrolyse glycogen into glucose
• glucose is released into the blood increasing blood glucose concentration

Question 24

How is glucose produced when the glycogen store is full?

Answer 24

(during extensive exercise or starvation etc)
glucagon activates enzymes which convert glycerol and amino acids into glucose (gluconeogenesis) which is released into blood

Question 25

What gland releases adrenaline

Answer 25

adrenal gland

Question 26

How does adrenaline produce glucose

Answer 26

- attaches to receptors on target cells and activate enzymes that hydrolyse glycogen into glucose

Question 27

Why does adrenaline increase glucose production

Answer 27

to provide glucose to cells for respiration and increase blood glucose to normal

Question 28

What is a first messenger ?

Answer 28

Hormones adrenaline and glucagon don't enter target cells directly but bind to surface receptors

Question 29

Outline how adrenaline/glucagon increases glucose

Answer 29

- binds to receptors on target cells - this activates enzyme adenly cyclase - adenlyate cyclase converts ATP into cyclic AMP (acts as second messenger) - AMP activates enzyme protein kinase - stimulates hydrolysis of glycogen to glucose and its released into blood

Question 30

What is Type 1 diabetes

Answer 30

- cells in the pancreas responsible for production of insulin are **destroyed** - individual produces no insulin at all

Question 31

What is Type 2 diabetes?

Answer 31

- cells have fewer insulin receptors or they are faulty and dont respond to insulin - so take up less glucose and convert less into glycogen so blood glucose remains high

Question 32

How is type 1 diabetes managed

Answer 32

individual **injects** themselves with insulin

Question 33

How is type 2 diabetes managed?

Answer 33

individual controls their blood glucose by controlling their **diet** - avoiding foods that cause rapid surge in blood glucose and by **regular exercise**