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BIOM2012 > Glucose Homeostasis > Flashcards

Glucose Homeostasis Flashcards

1
Q

For a healthy adult, the basal blood glucose is…

A

4-5mM

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2
Q

Why does the body regulate blood-glucose within a narrow range?

A

The body defends against low blood-glucose concentrations, hypoglycaemia

and high blood-glucose concentrations, hyperglycaemia

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3
Q

Beta-cells release…

A

Insulin to prevent hyperglycaemia

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4
Q

Alpha-cells release…

A

Glucagon to prevent hypoglycaemia

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5
Q

What mechanisms are responsible for maintaining such tight regulation of blood glucose?

A

While plasma glucose remains consistent, there is a robust increase in insulin concentrations with each meal.

Insulin acts to immediately lower blood glucose by promoting its up-take in cells.

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6
Q

Glucagon is constantly being degraded in the…

A

Post-absorptive state

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7
Q

Glucagon is maintained….

A

Between meals

*Important in preventing blood-glucose decline between meals

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8
Q

Glucose molecules are stored as…

A

Glycogen, readily available in the liver and muscles

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9
Q

When exercising, glycogen is catabolised to provide energy for contraction. T/F

A

True

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10
Q

Neurons can store glycogen. T/F

A

False.

Neurons cannot store glycogen

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11
Q

When glucose is limited, the brain switches to…

A

ketone-bodies; utilised for starvation

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12
Q

Exocrine cells:

A
  • Arranged in lobules that secrete a range of digestive enzymes, sodium bicarbonate, and other electrolytes into the duodenum.
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13
Q

Endocrine cells:

A

Secrete hormones into systemic blood

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14
Q

Alpha cells:

A

release glucagon –> catabolic, mobilise glucose, fatty and amino acids for energy production

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15
Q

Beta cells:

A

releases insulin –> anabolic, storage of glucose, fatty, and amino acids

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16
Q

Gamma cells:

A

releases somatostatin –> local to the pancreas to inhibit insulin and glucagon secretion

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17
Q

The prime blood-glucose lowering hormone in the body is…

A

Insulin

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18
Q

Excess glucagon production causes a _____ , a tumour of the pancreatic alpha cells that hyper-secretes glucagon.

A

gucagonoma

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19
Q

C-peptide is secreted via…

A

Insulin and pancreatic beta-cells

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20
Q

C-peptide is biologically inactive as a metabolic hormone. T/F

A

True

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21
Q

A person with elevated blood glucose levels will likely exhibit increased secretion of _____ from their pancreatic beta-cells within the islet of Langerhans.

A

insulin

22
Q

Insulin receptor substrates (IRS) are….

A

downstream and act as cytoplasmic protein scaffolds to organise signalling complexes

23
Q

*IRS1 and IRS2 are ubiquitously expressed; primary mediators of insulin-dependant regulation of glucose metabolism. T/F

A

True

24
Q

Glucose is hydro…

A

Hydrophillic

25
Q

GLUT1 is found at:

A
  1. Blood
  2. Blood Brain Barrier
  3. Heart

**Insulin dependant

26
Q

GLUT1-4 are insulin dependent. T/F

A

True

27
Q

GLUT2 is found at:

A
  1. Liver
  2. Pancreas
  3. Small intestine

**Low affinity

28
Q

GLUT3 is found at:

A
  1. Brain
  2. Neurons
  3. Sperm

**High affinity

29
Q

GLUT4 is found at:

A
  1. Skeletal muscle
  2. Adipose tissue
  3. Heart

**Moderate affinity

30
Q

GLUT5 is found at:

A

Enterocyte of interstitial epithilium (Luminal side)

31
Q

GLUT5 is insulin INdependant and a transporter of…

A

Fructose

32
Q

GLUTS are…

A

Sodium and ATP-dependant

Ubiquitous

33
Q

SGLTs stand for:

A

Sodium-Glucose Transport Systems

34
Q

SGLTs are…

A

Sodium dependant

Require ATP for a sodium gradient

35
Q

SLGT1 is found at:

A

Enterocyte of interstitial epithelium

**Glucose absorption

36
Q

SLGT2 is found at:

A

Proximal tubule of nephron in the kidney

37
Q

MAPKpathway:

A

Promotes cell growth.

38
Q

PI3K/PKBpathway:

A

Activated through IRS; promotes glucose transporters (GLUT4) translocation to cell surface.

39
Q

PI3K/mTORpathway:

A

Activated through IRS; promotes protein synthesis, inhibits proteolysis, cell growth.

40
Q

GLUT1→

A

Basal glucose uptake

Expressedinall tissue, Important in glucose crossing the blood brain barrier

41
Q

GLUT2→

A

Importantin pancreatic beta cells and liver hepatocytes

42
Q

GLUT3→

A

Basal glucose uptake, expressedinall tissue, important in CNS neurons

43
Q

GLUT4→

A

Insulin stimulatedglucose uptake

Expressedinmuscle (skeletal and cardiac) and fat adipocytes

44
Q

GLUT5→

A

Fructose transport in small intestine

45
Q

Which of the following pathways are activated by insulin signal transduction?

A

MAPK: promotion of cell growth

P13K/MTOR: Promotion of protein synthesis, inhibits proteolysis and cell growth

P13K/PKB - promotion of movement of GLUT4 to the cell surface in muscle and adipose cells

46
Q

How does the body ensure that insulin is secreted in response to digested nutrients.

A

The anatomical arrangement that allows nutrient rich blood from the GI-tract travels via the pancreas –> liver via the hepatic portal vein

47
Q

How does insulin promote glucose uptake in the liver after a meal?

A
  • Via expression and activation of enzymes that promotestorage and utilisation of glucose.
  • Insulin maintains a concentration gradient in hepatocytes that favours glucose intake via GLUT2 (and other GLUTs) transporters (glucose movement is down the concentration gradient).

This occurs after a meal, when the blood glucose concentration is high.

48
Q

Insulin binds to its receptor and activates the…

A

Tyrosine kinase domain

49
Q

Insulin Receptor Substrates are phosphorylated by receptor kinases on tyrosine residues. T/F

A

True

50
Q

Within hepatocytes, insulin…

A

PromotesGlycogenesis(storage of glycogen) and inhibitsGlycogenolysis (breakdown of glycogen to glucose)

BIOM2012 (6 decks)

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