Glucose homeostasis Flashcards

1
Q

What are the exocrine cells in the pancreas?

A

Acinar cells that secrete enzymes that are passed into the duodenum.

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2
Q

What are Islet of Langerhans?

A

Groups of pancreatic cells secreting insulin and glucagon.

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3
Q

What is the difference between alpha and beta cells in the islets of Langerhans?

A

Alpha cells secrete glucagon whereas beta cells secrete insulin.

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4
Q

What effect does insulin have on the plasma?

A

It decreases glucose, amino acids and free fatty acids.

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5
Q

What effect does glucagon have on the plasma?

A

It increases glucose and ketones.

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6
Q

What do delta cells do?

A

Produce and release somatostatin which suppresses GI motility and the release of insulin and glucagon.

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7
Q

What is the structure of insulin?

A

It is made up of an A chain (21 a.a), a B chain (30 a.a) and a c chain. The c-peptide is inactive.

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8
Q

What is insulin degraded by?

A

Insulinase in the liver and kidneys.

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9
Q

When is insulin released?

A

In response to changes in glucose/ATP.

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10
Q

How is insulin secreted?

A

It occurs via a calcium-dependent exocytosis.

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11
Q

What happens when insulin binds to the insulin receptor?

A

There is dimerization, autophosphorylation that causes effects on intracellular kinases and following effects on key enzymes.

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12
Q

What effect does insulin have on carbohydrate metabolism?

A

It facilitates the entry of glucose into muscle, it stimulates the liver to store glucose as glycogen and decreases the concentration of glucose in the blood.

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13
Q

What effect does insulin have on lipid metabolism?

A

It promotes the synthesis of fatty acids in the liver (when glycogen is saturated) which leads to an increase in lipoproteins in the circulation to release fatty acids. It inhibits the breakdown of fat in adipose tissue and promotes glycerol synthesis from glucose and increases triglyceride synthesis.

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14
Q

How does insulin cause cells to take up glucose?

A

When released, it causes glucose transporters to be released from storage microsomes and migrate to the cell membrane. Glucose can then be taken up by the cell.

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15
Q

When happens when glucose is taken up by muscle cells?

A

It is converted into glucose-6-P which is then converted into lactic acid, releasing energy.

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16
Q

What happens when insulin acts on the liver?

A

It causes glucose-6-P to be converted to glycogen, as well as it combining with lactic acid, amino acids and fatty acids to form lipoproteins.

17
Q

What effect does insulin have on adipose tissue?

A

It causes amino acids, glucose and lipoproteins (from the liver) to be taken up and converted into triglycerides.

18
Q

What happens if glucose levels rise above the normal?

A

The homeostasis is disturbed and beta cells release insulin. This causes an increased rate of glucose uptake, increased glycogenesis, increased protein and fat synthesis.

19
Q

What is the normal glucose level in the blood?

A

70-110mg/dl.

20
Q

How many amino acids is glucagon made up of?

A

29.

21
Q

What does glucagon stimulate?

A

Glycogenolysis, gluconeogenesis and increases the breakdown of fats.

22
Q

What is the body’s response if glucose levels fall below normal?

A

The homeostasis is disturbed, alpha cells release glucagon which causes increased glycogenolysis, fats to fatty acids, protein breakdown and increased gluconeogenesis.

23
Q

What is hypoglycaemia?

A

When the blood glucose is below the normal level (3mM).

24
Q

What are some of the effects of hypoglycaemia?

A

Impaired vision, slurred speech, staggered walking, mood change, confusion, coma and death.

25
Q

What is hyperglycaemia?

A

Diabetes mellitus - blood glucose is above the normal level.

26
Q

What are risk factors and features of type 1 diabetes?

A

Family history, genetics, infection. It appears suddenly and is incurable.

27
Q

What are the risk factors and features of type 1 diabetes?

A

Body weight, inactivity, family history, age. It can go undiagnosed or unnoticed for years and can be cured with diet and lifestyle changes.

28
Q

What is gestational diabetes?

A

It is associated with pregnancy and poses serious risks to the mother and child. There is an increased risk of developing type 2 diabetes due to it.