Ketogenesis Flashcards

1
Q

What are the sources of energy in the body

A

Carbohydrates
Fats
Lipids

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2
Q

How long can glycogen stores sustain energy levels

A

12 hours

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3
Q

How long can lipid energy reserves provide energy

A

up to 12 weeks

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4
Q

When is protein stores used

A

Used when muscle glycogen stores fail

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5
Q

What do fatty acids contain

A

Carboxylic head with aliphatic group

Saturated or unsaturated

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6
Q

What are most fatty acids derived from

A

Triglycerides and phospholipids

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7
Q

Where does fatty acid oxidation occur

A

Cytoplasm

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8
Q

Describe Acyl-CoA

A

12 carbons

Can be diffuse into the mitochondrial membrane

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9
Q

What is the order of fatty acid activation

A

Fatty acid

Acyl adenylate

Acyl-CoA

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10
Q

What does fatty acid use and produce

A

Use - ATP, CoA-SH

Produce - PPi, AMP

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11
Q

What are the features of most dietary acids

A

> 14 carbons

Taken through mitochondrial membrane using carnitine shuttle

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12
Q

What happens to most acetyl-CoA under normal metabolic conditions

A

Utilised via the TCA acid cycle to produce glucose

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13
Q

What happens to a small amount of acetyl-CoA under normal metabolic conditions

A

Converted into ketones

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14
Q

What are ketones produced

A

By liver from acetyl-CoA

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15
Q

3 examples of ketones

A

Acetone

Acetoacetate

Beta-hydroxybutyrate

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16
Q

What happens during high rate of fatty acid oxidation

A

Large amounts of acetyl-CoA are generated

17
Q

Why does ketogenesis occur

A

When large amounts of acetyl-CoA are produced

Exceeds capacity of the TCA cycle

18
Q

In ketogenesis what can acetoacetate undergo

A

Spontaneous decarboxylation to acetone

OR

Enzymatically converted to beta-hydroxybutyrate

19
Q

Where can acetoacetate:succinyl-CoA be found

A

All tissues but hepatic tissue

20
Q

What are ketone bodies utilised by

A

Extrahepatic tissues through conversion of beta-hydroxybutyrate and acetoacetate to acetoacetyl-CoA

Required acetoacetate:succinyl-CoA

21
Q

What is ketogenesis regulated by

A
  1. Release of free fatty acids from adipose tissue
  2. High concentration of glycerol-3-phospahte in the liver results in triglyceride production, whilst low level results in increased ketone body production
  3. Demand for ATP is high, acetyl-CoA is likely to be further oxidised via the TCA cycle to carbon dioxide
  4. Fat oxidation is dependant upon the amount of glucagon (activation) or insulin (inhibition) present
22
Q

Describe ketoacidosis

A

Occurs in insulin-dependent diabetics when dose is inadequate or because of increased insulin requirement (infection, trauma, acute illness)

Often presenting feature in newly diagnosed type 1 diabetics

Occurs in chronic abuse

Patient presents with hyperventilation and vomiting

23
Q

Diabetic ketoacidosis

What are the three things that can occur in insulin deficiency

A

Inhibition of glycolysis and stimulation of gluconeogenesis

Glycogen breakdown and inhibition of glycogen synthesis

Increased lipolysis (increased fatty acids)

24
Q

What does Inhibition of glycolysis and stimulation of gluconeogenesis lead to

A

Hyperglycaemia

25
Q

What does Glycogen breakdown and inhibition of glycogen synthesis lead to

A

Hyperglycaemia

26
Q

What does increased lipolysis (increased free fatty acids) lead to

A

Increased acetoacetate and beta-hydroxybutyrate

27
Q

What are the consequences of ketoacidosis

A

Excessive ketones lower pH in the blood - impairs the ability of haemoglobin to bind to oxygen

pH - low
pO2 - high
pCO2 - low
HCO3 - low

28
Q

What are ketones

A

Relatively strong acids (pKa approx. 3.5)