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A2 Biology Topic 6C > 2. Negative Feedback Mechanisms And Glucose Concentration > Flashcards

2. Negative Feedback Mechanisms And Glucose Concentration Flashcards

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1
Q

What do negative feedback mechanisms do ?

A

Keep blood glucose conc normal.

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2
Q

What detects change in blood glucose conc?

A

Pancreas.

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3
Q

What happens when the pancreas detects blood glucose is too high?

A

B cells secrete insulin and alpha cells stop secreting glucagon.
Insulin then binds to receptors on liver/ muscle cells.
And they response to decease blood glucose conc eg glycogenesis
Blood glucose returns to normal.

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4
Q

How do the liver and muscle cells respond when blood glucose is too high?

A

They take up more glucose.
Glycogenesis activates.
Cells respire more glucose.

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5
Q

What happens when the pancreas detects blood glucose is too low?

A

Alpha cells start secreting glucagon and beta cells stop secreting Insulin.
Glucagon then binds to receptors on liver cells.
Liver cells respond by increasing the blood glucose conc eg glycogenolysis
Blood glucose returns to normal

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6
Q

How to liver cells respond when blood glucose is too low?

A

Glycogenolysis
Gluconeogeneis activated.
Cells respire less glucose

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7
Q

What liver cells and muscles cells known as ?

A

Effectors.

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8
Q

What does genesis mean ?

A

Making.

Making glycogen

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9
Q

What does lysis mean ?

A

Splitting

Splitting glycogen.

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10
Q

What does Neo mean?

A

News

Making new glucose.

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11
Q

What are glucose transporters?

A

Channel proteins.

Allow glucose to be transported across membrane.

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12
Q

What glucose transporter do skeletal and cardiac muscles contain?

A

GLUT4

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13
Q

What does GLUT4 do when insulin levels are low?

A

GLUT4 stored in vesicles in cytoplasms.
When insulin binds to receptors on cell surface membrane it triggers movement of GLUT4 to membrane.
Glucose then transported into cell through GLUT4 protein by facilitated diffusion.

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14
Q

What is the role of facilitated diffusion?

A

Transports large or charged particles across a cell membrane down a concentration gradient from high to Low.
Passive - no energy

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15
Q

So what happens to GLUT4 when no insulin has binded to receptor?

A

GLUT4 remains in vesicles until insulin has binded to receptors.
After the GLUT4 can go to membrane allowing glucose in via FD

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16
Q

What is adrenaline ?

A

Hormone

17
Q

Where is adrenaline secrete from ?

A

Adrenal gland found above kidney

18
Q

When is adrenaline secreted?

A

When there’s a-low concentration of glucose in blood.
Stressed
Exercise.

19
Q

What is adrenalines role?

A

Binds to receptors in cell membrane of liver cells and increases blood glucose.

20
Q

What does adrenaline do to increase blood glucose?

A

Activates glycogenolysis breakdown of glycogen
Inhibits glycogenesis.
Activates glucagon secretion and inhibits insulin secretion- increases glucose concentration.

21
Q

What does adrenaline get the body ready for ?

A

Action.

Making more glucose available for muscles to respite.

22
Q

How adrenaline and glucagon activate glycogenolysis inside a cell even though they bind to receptors on outside of cell, how do they do this ?

A

Second messenger model.

23
Q

What does the second messenger model mean?

A

Binding of the hormones to cell receptors activates enzymes on inside of cell membrane - producing chemical known as second messenger.

24
Q

Role of second messenger ?

A

To activate other enzymes in cell to bring about a response ?

25
Q

How do adrenaline and glucagon activate glycogenolysis?

A

They have specific tertiary structures which have complementary shape to respective hormones.
This activates enzyme called adenylate Cyclades.

26
Q

What does activated adenylate cyclase do ?

A

Converts ATP into chemical called cyclic AMP -cAMP, this is a second messenger.
This then activates enzyme called protein kinase A.

27
Q

What does protein kinase A do?

A

Activates cascade that breaks down glycogen into glucose -glycogenolysis.

28
Q

Summarise process of adrenaline and glucagon binding to receptor?

A

Activates adenylate cyclase.
Activates 2nd messenger cAMP
Activates protein kinase A.
Glycogen breaks down into glucose.

29
Q

What does hypoglycaemia mean?

A

Low blood conc.

A2 Biology Topic 6C (7 decks)

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