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ENDOCRINOLOGY > 1a Glucose Homeostasis > Flashcards

1a Glucose Homeostasis Flashcards

1
Q

What is significantly impaired when glucose concentration falls below normal levels?

A

Cerebral function

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2
Q

What is glucose particularly important for?

A

The functioning of the central nervous system

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3
Q

What is hypoglycemia?

A

Blood glucose concentration levels fall below a normal levels

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4
Q

What can happen is blood glucose Concentration falls below 2mmol/L

A

Unconsciousness, coma and ultimately death

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5
Q

What does persistent hyperglycemia result in?

A

Diabetes mellitus

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6
Q

What hormones act against hypoglycemia?

A

Glucagon
Cortisol
Growth hormone
Catecholamines

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7
Q

What is the most prevalent form of diabetes?

A

Type 2 diabetes mellitus

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8
Q

What are the three types of diabetes

A

Type 1 DM
Type 2 DM
maturity onset diabetes of the young

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9
Q

What is meant by a retroperitoneal structure?

A

Has a peritoneum on the anterior side only

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10
Q

What are the small clumps of cells in the pancreas called?

A

Islets of Langerhans

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11
Q

What are exocrine acinar cells?

A

Cells that generate exocrine secretions

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12
Q

What are the three types of islet cells?

A

Alpha, beta and delta cells

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13
Q

What are the alpha cells involved with?

A

Glucagon secretion

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14
Q

What are the beta cells in the islets of langerhans involved with?

A

Insulin secretion

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15
Q

What are the delta cells in the islet of langerhans involved with?

A

Somatostatin secretion

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16
Q

What are gap junctions?

A

They allow small molecules to pass directly between cells

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17
Q

What are tight junctions?

A

Create small intercellular spaces

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18
Q

What type of communication is found between the islet cells?

A

Paracrine communication

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19
Q

What does insulin do?

A

Stimulates growth and development and reduces blood glucose

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20
Q

What affect does insulin secreted from the beta cells have?

A

Increased:
- Glycolysis
- Glycogenesis
- Glucose transport into cells via GLUT 4

21
Q

Where is GLUT 4 predominantly expressed?

A

Adipocytes and skeletal muscle

22
Q

When blood glucose is high, what is released?

A

Insulin from the beta cells as well as some glucagon from the alpha cells to ensure that hypoglycaemia doesn’t occur

23
Q

Aside from glucose effects, what else does insulin do?

A

Increase amino acid transport, protein synthesis and lipogenesis

Decrease in lipolysis

24
Q

What is released when blood glucose levels are lowered?

A

Alpha cells release glucagon

25
Q

What affect does glucagon have?

A

INCREASED:
- gluconeogenesis
- lipolysis
- blood glucose
- amino acid transport to the liver
- hepatic glycogenolysis

26
Q

Is GLUT 2 insulin sensitive?

A

No

27
Q

What is the main glucose sensor?

A

Glucokinase (hexokinase as IV)

28
Q

What is GLUT 2’s affinity for glucose, and what does this mean?

A

High affinity for glucose, so whatever glucose is in our blood stream is therefore reflected in the intracellular concentration of the beta cell

29
Q

Does glucose 6 phosphate inhibit glucokinase?

A

No

30
Q

Why do glucose 6 phosphate levels give a good indication of glucose levels as well?

A

Glucose to glucose 6 phosphate is a continual conversion by glucokinase therefore the amount of glucose present is equal to glucose 6 phosphate

31
Q

How is insulin released?

A

The ATP produced from glycolysis inhibits the potassium ion channels, meaning K+ remains in the beta cells
therefore, there is an intracellular influx of Ca2+ which triggers the insulin to be released from the beta cells

32
Q

What is meant by a graded response of insulin production?

A

Insulin isn’t released in an all or nothing manner, continually released when needed and the amount released changes over time

33
Q

What is pro insulin cleaved into?

A

Pro insulin and C-peptide

34
Q

What happens to C peptide levels after a big meal?

A

Increase

35
Q

What happen to someone’s C peptide levels when a person with type 1 diabetes eats a meal?

A

They are low - this is because C peptide levels are only a measure of endogenous insulin, and doesn’t include the insulin which they have injected following the meal

36
Q

What is the difference between oral and intravenous glucose in terms of plasma insulin production? And what is this effect called?

A

Oral is significantly higher - increatin effect

37
Q

Transcription of what gene produced Glucagon like peptide 1?

A

Pro-glucagon gene

38
Q

Where is glucagon like peptide found?

A

In the gut

39
Q

What is the effect of glucagon like peptide 1?

A

Stimulated insulin and suppresses glucagon

40
Q

What effect does glucagon like peptide1 do to us?

A

Increases feeling of fullness

41
Q

Wh6 does GLP1 have a short half life?

A

Rapidly degraded by enzymes dipeptidyl peptidase 4

42
Q

What is GLP1 used in the treatment of?

A

Diabetes mellitus

43
Q

What is meant by the first phase insulin release?

A

This is following a meal, when a diabetics insulin levels do increase slightly, but much less than a healthy individuals, and stay elevated

44
Q

How does the insulin receptor work?

A
  1. Insulin binds to alpha subunit
  2. Causes a confirmation change in the tyrosine kinase domain of the beta sun unit
  3. This causes the movement of GLUT 4 from intracellular space to cell membrane so glucose can be absorbed
45
Q

What part of the insulin receptor does insulin initially bind to?

A

Extracellular domain - alpha subunit

46
Q

What percentage of the pancreas gland is involved in exocrine secretions?

A

98%

47
Q

Where may you find insulin receptors?

A

Liver, muscle and fat

48
Q

What is the incretin effect?

A

When the production of plasma insulin is significantly larger and higher following giving oral glucose to patients

ENDOCRINOLOGY (20 decks)

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