eLFH - Metabolism Physiology Part 2 Flashcards

1
Q

Normal blood glucose range

A

4 - 8 mmol/L

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2
Q

Hormones with role in decreasing blood glucose levels

A

Insulin

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3
Q

Hormones with role in increasing blood glucose levels

A

Glucagon (main one)

Catecholamines
Cortisol
Growth hormone
Somatostatin
Thyroxine
Oestrogen / Progesterone

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4
Q

Glycolysis definition + location

A

Process by which glucose is broken down to pyruvate to release energy

Occurs in all cells

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5
Q

Glycogenolysis definition + location

A

Process by which glycogen is broken down to glucose

Occurs mainly in liver and muscles

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6
Q

Glycogenesis definition + location

A

Process by which glucose is converted to glycogen

Occurs mainly in liver and muscles

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7
Q

Gluconeogenesis definition + location

A

Process by which glucose is synthesised from non-carbohydrate sources (E.g. amino acids, glycerol)

Occurs mainly in liver and kidneys

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8
Q

Structure of insulin

A

51 amino acids

2 peptide chains linked by disulphide bridges

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9
Q

Where is insulin secreted from

A

Beta cells in islets of Langerhans in pancreas

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10
Q

Action of Insulin at receptor level

A

Acts via tyrosine kinase receptors on many different cell types

Results in translocation of glucose transporters to the cell membrane to increase glucose uptake

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11
Q

Actions as a result of insulin release

A

Increases:
Glucose uptake
Glycogen synthesis
Protein synthesis
Fat synthesis
Potassium uptake by cells

Decreases:
Gluconeogenesis in liver

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12
Q

Structure of Glucagon

A

29 amino acids

Single polypeptide chain

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13
Q

Where is Glucagon secreted from

A

Alpha cells in Islets of Langerhans in pancreas

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14
Q

Action of Glucagon at receptor level

A

Acts on liver via G-protein linked receptors

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15
Q

Actions as a result of glucagon release

A

Increases:
Glycogenolysis in liver
Gluconeogenesis
Lipolysis including ketoacid formation

Stimulates release of insulin, growth hormone and somatostatin

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16
Q

Actions of Glucagon on cardiovascular system

A

Causes non-adrenergic inotropic and chronotropic effects on heart

Hence use in Beta blocker overdose

17
Q

Factors which increase insulin levels

A

Raised glucose
Glucagon (paracrine effect)

Drugs:
Phosphodiesterase inhibitors
Sulphonylureas

18
Q

Factors which decrease glucagon levels

A

Raised glucose
Raised ketoacids
Raised free fatty acids
Insulin

19
Q

Factors which decrease insulin levels

A

Alpha 2 adrenoreceptor stimulation
Insulin (autoinhibition)

Drugs:
Diazoxide
Thiazide diuretics
Beta blockers

20
Q

Diazoxide drug use

A

Persistent hypoglycaemia

21
Q

Factors which increase glucagon levels

A

Low glucose

Beta 2 adrenoreceptor stimulation (e.g. stress, exercise)

22
Q

Factors which inhibit both insulin and glucagon release

A

Insulin
Somatostatin

23
Q

Factors which stimulate both insulin and glucagon release

A

Amino acids
Gastrointestinal hormones
Vagal stimulation

All above increase after a meal

24
Q

Effect of catecholamines and sympathetic nervous system on blood glucose

A

Net increase in blood glucose by:
- Glycogenolysis
- GNG
- Lipolysis
- Inhibits insulin secretion via pancreatic alpha 2 receptors
- Stimulates glucagon secretion via pancreatic beta 2 receptors

25
Q

Effect of cortisol on blood glucose

A

Net increase in blood glucose over hours to days by:
- GNG
- Protein breakdown
- Reduced glucose utilisation by cells
- Lipolysis
- Promotion of keto-adaptation

26
Q

Effect of growth hormone on blood glucose

A

Net increase in blood glucose by catabolic actions:
- Glycogenolysis
- Lipolysis
- Promotion of keto-adaptation

Also has anabolic action of protein synthesis

27
Q

Secretion of somatostatin

A

Released by pancreatic delta cells and the hypothalamus in response to high glucose, amino acids and fatty acids

28
Q

Effect of somatostatin on blood glucose

A

Net increase in blood glucose by:
- Inhibits gut motility and secretion - makes food available over longer period of time

  • Inhibits release of insulin and glucagon
29
Q

Effect of thyroxine on blood glucose

A

Net increase in blood glucose by:
- Increases glucose absorption from gut
- Glycogenolysis
- GNG

30
Q

Effect of oestrogen and progesterone on blood glucose

A

Net increase in blood glucose vis increased peripheral insulin resistance

Hence gestational diabetes

31
Q

Effect of hypothermia on blood glucose

A

Increases glucose levels