CONTROL OF BLOOD GLUCOSE

Question 1

why does blood glucose need to be controlled

Answer 1

all cells need energy to work

glucose is a respiratory substrate

Question 2

what is the rough conc of blood glucose in blood

Answer 2

around 90mg per 100cm3

Question 3

when does blood glucose conc rise

Answer 3

after eating

Question 4

when does blood glucose conc fall

Answer 4

after exercise

Question 5

what 2 hormones control blood glucose conc

Answer 5

insulin and glucagon

Question 6

how do insulin and glucagon work

Answer 6

They travel in the blood to their target cells (effectors)

They’re secreted by clusters of cells in the pancreas called ISLETS OF LANGERHANS

Question 7

What cells secrete insulin into the blood

Answer 7

beta cells

Question 8

what cells secrete glucagon into the blood

Answer 8

alpha cells

Question 9

what is the role of insulin

Answer 9

insulin lowers blood glucose conc when its too high
It binds to specific receptors on cell membrane of liver cells and muscle cells
Increases the permeability of muscle cell membranes to glucose
Cell takes up more glucose
This involves increasing the number of channel proteins in the cell membrane
Insulin also activates enzymes in liver and muscle cells which convert glucose to glycogen
Can then store glycogen in cytoplasm as energy source

Question 10

what is the role of glucagon

Answer 10

glucagon raises blood glucose conc when its too low
Binds to specific receptors on cell membrane of liver cells
Activates enzymes in liver cells that break down glycogen to glucose (glycogenolysis)
Activates enzymes involved in the formation of glucose from glycerol and amino acids

Question 11

what is glycogenesis

Answer 11

the process of forming glycogen from glucose

Question 12

what is glycogenolysis

Answer 12

the process of breaking down glycogen to glucose

Question 13

What is gluconeogensis

Answer 13

the process of forming glucose from non carbohydrates

Question 14

why is hormone transmission slower than nerve impulse transmission

Answer 14

hormones travel in the blood and are therefore slower

However hormones are not broken down as quickly/ easily as nerve impulses and therefore their effects last for longer

Question 15

what is GLUT4

Answer 15

a glucose transporter

a channel protein that transports glucose

Question 16

what happens to GLUT4 when insulin levels are low

Answer 16

GLUT4 is stored in vesicles of the cytoplasm

Question 17

what happens to GLUT4 when insulin binds to receptors

Answer 17

when the insulin binds to receptors on the CSM it triggers the movement of of GLUT4 to the membrane
Glucose can be transported into the cell through the GLUT4 protein by facilitated diffusion

Question 18

what does adrenaline do to blood glucose concentration

Answer 18

alike to glucagon adrenaline increases blood glucose concentration

Question 19

how does adrenaline increase blood glucose concentration

Answer 19

Adrenaline is secreted when there is a low conc of glucose in blood, when your stressed and when your exercising
It binds to the receptors in the cell membrane of liver cells
Activates glycogenolysis (glycogen to glucose)
Inhibits glycogenesis (glucose to glycogen)
It also activates glucagon secretion and inhibits insulin secretion which increases glucose conc which gets body ready for exercise as more glucose (respiratory substrate)

Question 20

How do adrenaline and glucagon act

Answer 20

Via a second messenger

Question 21

what is a second messenger and give an example

Answer 21

the chemical signal created by the conversion of ATP
cyclic AMP (cAMP)

Question 22

How do adrenaline and glucagon act inside the cell when they attach to receptors on the outside

Answer 22

The receptors have specific tertiary structures
Adrenaline and glucagon bind and activate an enzyme called adenylate cyclase
Activated adenylate cyclase converts ATP to a chemical signal (second messenger) called cAMP
cAMP activates an enzyme called protein kinase A
Protein kinase A activates a cascade of reactions that breaks down glycogen into glucose (glycogenolysis)

Question 23

what is diabetes

Answer 23

a condition where blood glucose can’t be controlled properly
type 1 and type 2

Question 24

what is type 1 diabetes

Answer 24

Immune system attacks B cells in the islets of Langerhans
They then can’t produce any insulin
After eating, blood glucose level rises and stays high (hyperglycaemia)
Can result in death if not treated
Kidneys can not re absorb all of this glucose so some of it is excreted as urine

Question 25

what is type 2 diabetes

Answer 25

It occurs when B cells don’t produce enough insulin or when the body cells don’t respond properly to insulin
The cells don’t respond properly because their receptors on their membranes don’t work properly so the cells don’t take up enough glucose
Resulting in blood glucose levels being higher than normal

Question 26

How is type 1 diabetes treated

Answer 26

Insulin therapy
Most people need regular insulin injections throughout day
Some people use a regular insulin pump continually
Insulin therapy has to be monitored carefully as too much insulin can result in a dangerous drop in blood glucose levels (hypoglycaemia)

Question 27

when and why may you get type 2 diabetes

Answer 27

Usually acquired later in life
Often linked with obesity
More often associated within families
Other risk factors include lack of exercise, age and poor diet

Question 28

how is type 2 diabetes treated

Answer 28

eating healthy
balanced diet
losing weight
regular exercise

glucose lowering medication can be taken
insulin injections may be needed

Question 29

what have food companies done in response to criticism

Answer 29

found sugar alternatives to sweeten food/ drink

reduced the sugar/ fat/ salt content of products

Question 30

in the quantitative benedicts test describe how colour varies with conc of glucose

Answer 30

as glucose conc increases the blue colour of the Benedictus gets paler
use colorimeter to measure