T2 L6: Liver Homeostasis Flashcards

1
Q

What are the 3 main energy sources for ATP synthesis?

A

Glucose, long chain fatty acids, and amino acids

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2
Q

What are long chain fatty acids stored as?

A

Triglycerides

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3
Q

Where are the fuels for energy synthesis stored?

A

In the liver and adipose tissues

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4
Q

What are 4 reasons why cerebral cells are so sensitive to hypoglycaemia?

A
  1. They derive their energy from aerobic respiration
  2. They can’t store glucose in significant amounts or synthesise glucose
  3. They can’t metabolise substrates others than glucose or ketone bodies
  4. Glucose entry into the brain is not facilitated by hormones so it’s limited
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5
Q

What is gluconeogenesis and where does it occur?

A

It’s synthesis of glucose from non-carbohydrate precursors like amino acids, glycerol, and lactate in the liver or kidneys

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6
Q

What is glycogenolysis and where does it occur?

A

It’s the metabolism of liver glycogen stores

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7
Q

What is glycolysis and where does it occur?

A

It’]s the oxidation of glucose by peripheral tissues

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8
Q

At what range is plasma glucose maintained at?

A

2.5 - 8 mM

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9
Q

When is dietary glucose the main source of blood glucose?

A

When glucose is being absorbed from the small intestine (2-3 hours following a meal)

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10
Q

How long do glycogen stores last?

A

12-24 hours

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11
Q

Which pancreatic cells secrete glucagon?

A

Alpha cell

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12
Q

Which pancreatic cells secrete insulin?

A

Beta cells

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13
Q

Where are Glut 1 transporters found?

A

Erythrocytes, muscles, brain, kidneys, colon, placenta, and foetal tissue

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14
Q

Where are Glut 2 transporters found?

A

Liver and pancreatic Beta cells

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15
Q

Where are Glut 3 transporters found?

A

Brain

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16
Q

Where are Glut 4 transporters found?

A

Skeletal muscles and adipose tissue

17
Q

Which Glut transporter is sensitive to glucose?

A

Glut 4

18
Q

Where are Glut 5 transporters found?

A

Small intestine (fructose transporter)

19
Q

What are some properties of Glut 1 glucose transporters? Their affinity?

A

They are responsible to basal glucose uptake and decrease in glucose deprivation. Affinity = 1mM

20
Q

What are some properties of Glut 2 glucose transporters? Their affinity?

A

Have a high capacity, low affinity of 15-20 mM. Takes up glucose only at very high [glucose] and conserves it for other tissues

21
Q

What are some properties of Glut 3 glucose transporters? Their affinity?

A

They are predominantly neuronal and supply tissues with high energy demands. High affinity of 1 mM irrespective of [blood glucose]

22
Q

What are some properties of Glut 4 glucose transporters? Their affinity?

A

Affinity = 5 mM. Found on insulin sensitive tissues

23
Q

How do Glut 4 glucose transporters work?

A

They are found in cell cytosol so when insulin binds to a receptor, cell signalling occurs which translocates Glut 4 into the membrane. Then Glut 4 can transport glucose

24
Q

What are some properties of cellular effects of insulin?

A
  • occur within minutes
  • don’t require protein synthesis
  • occur in very low [insulin]
25
Q

What are some immediate effects of insulin on tissues?

A

Increased rate of uptake of glucose into cells, and modulation of enzymes involved in glucose metabolism

26
Q

What are some long-lasting effects of insulin on tissues?

A

Increased expression of enzymes for glycogen triglyceride synthesis, inhibition of lipolysis, and insulin functions as a growth factor for some cells like fibroblasts

27
Q

What is the pentose phosphate pathway (PPP)?

A

A pathway present in all cells that uses branches of G-6-P to produce ribose Phosphate and NADPH

28
Q

What is ribose phosphate used to produce?

A

RNA and DNA

29
Q

What is NADPH used to produce?

A

For reductive biosynthesis and to maintain redox balance in cells

30
Q

Why do red blood cells do anaerobic respiration?

A

Because they don’t have mitochondria which is the site of the TCA cycle and the e- transport chain