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Glucose Homeostasis Flashcards

(33 cards)

1
Q

What is the normal blood glucose concentration?

A

4-5mmol/L

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2
Q

At what blood glucose concentration does unconsciousness, coma or death can occur

A

When it falls below 2mmol/L

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3
Q

What does persistent hyperglycaemia lead to

A

Diabetes Mellitus

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4
Q

What are the hormones that act to increase glucose levels in plasma

A
  • Glucagon
  • Cortisol
  • GH
  • Catecholamines
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5
Q

What hormone(s) act to decrease blood glucose concentration?

A

Insulin

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6
Q

What type of diabetes is most prevalent? Describe the percentages

A

Type 2

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7
Q

What is the structure is the pancreas gland?

A

Retroperitoneal structure

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8
Q

Describe the micro anatomy of the pancreas exhaustively and outline functions

A

98% Excorine Acinar cells- secrete hormones into small intestine via duct

2% ;- islets of langerhans

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9
Q

What are the 3 type of cells in the Islets of Langerhans and what do they secrete?

A

Alpha- glucagon

Beta- insulin

delta- somatostatin

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10
Q

What are the type of junctions between islets of langerhan cells and what is their significance?

A

Gap junction - allow small molecules to pass between cells- paracrine communication

Tight junction- create small intercellular spaces.

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11
Q

What type of communication is between islets cells

A

Paracrine

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12
Q

What does insulin do?

A

Reduce blood glucose levels hence stimulate growth and development

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13
Q

What other hormones affect insulin secretion

A

Glucagon inhibit beta cells

Somatostatin inhibit beta cells

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14
Q

What is the effect of insulin?

A

Glycogenesis

Uptake of glucose via GLUT4

Glycolysis

Increase protein synthesis- amino acid transport increase

Lipolysis decreases

Lipogenesis increases

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15
Q

What’s the effect of glucagon in the body

A

Hepatic Glycogenolysis

Gluconeogenesis

Amino acid transfer into liver

Increased lipolysis

Hence glucose blood levels increase

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16
Q

Describe the intracellular process in beta cells which stimulates the release of insulin

A

Glucose enters beta cells via GLUT2

Glucose converted to G-6 phosophate via Glucokinase IV

ATP synthesised; inhibits k+ ion channels.

More K+ stay in beta cells.

K+ stimulates Ca2+ channels

Ca2+ influx and stimulates production and release of insulin from vesicles.

17
Q

Describe the synthesis of insulin

A

Insulin is made from pro-insulin

C-peptide is cleaved off from pro-insulin

18
Q

What key hormone is involved in the incretin effect?

A

Glucagon like peptide-1 (GLP)

19
Q

Describe where and how GLP-1 is made

A

Gut hormone

Secreted in response to nutrients in gut

Made from L-cell; a transcription product of pro-glucagon gene.

20
Q

What is the function of GLP-1?

A

STIMULATES INSULIN

Suppresses glucagon

Increases satiety

21
Q

What causes the short half life of GLP-1 and what treatment can GLP-1 can be used for.?

A

Short half life- due to rapid degradation from the enzyme dipeptidyl peptidase- 4

(DPPG-4 inhibitor) is treatment used to increase GLP-1

Used in treatment of diabetes mellitus

22
Q

Describe the insulin receptor and how it responds when insulin binds to it?

A

Insulin bind to EXTRACELLULAR DOMAIN of insulin receptor. I.e. binds to alpha subunit

This causes conformational change in Tyrosine kinase domains of beta subunits?

23
Q

Describe incretin effect

A

In normal, When you eat plasma insulin goes up significantly and peaks 1hr after eating and decreases to reach normal levels.

when there’s a significant increase in insulin levels when given oral glucose as opposed to given IV glucose (this is due to GLP1 and GIP) .

people with type 2 diabetes don’t show this

24
Q

Describe the first phase insulin release graph for type 2 diabetes and normal people

A

For type 2: after glucoses given; insulin increases but not very much an decrease gradually but not to the level of normal glucose tolerance

25
Describe the role of somatostatin in glucose hormone regulation
Inhibits insulin AND glucagon
26
During an increase in blood glucose levels, what factors STIMULATE beta cells?
Some amino acids Some GI hormones Blood glucose PNS activity- rests and digest for growth SNS activity via beta adregenic receptors
27
During an increase in blood glucose levels what chemicals inhibits beta cells
Glucagon Somatostatin SNS via alpha adregenic receptors - need **glucose to be in the blood** to get to muscles and other parts of the body
28
What is the overall response to an increase in blood glucose levels
Insulin released to ensure glucose levels doesn’t go above physiological values
29
During a decrease in blood glucose levels what chemicals stimulate the alpha cells
Some amino acids Some GI hormones Blood glucose SNS activity via alpha adregenic receptors PNS activity
30
During a decrease in blood glucose levels what chemicals inhibit the alpha cells
Somatostatin Insulin
31
What is the aim of the release of glucagon during a reduction in blood glucose levels ?
To make sure that blood glucose levels doesn’t go below the physiological values
32
What is the prevalence of diabetes in UK
7%
33
Draw or describe the process of insulin release? What is the rate limiting step? What is the function of K+?
Glucokinase is rate limiting step K+ stimulate Ca2+ channels