Metabolic Stores COPY COPY Flashcards

1
Q

Where is glycogen stored?

A

Mainly in liver and skeletal muscle

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2
Q

Glycogen can cover energy needs for how long?

A

3-5 hours

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3
Q

When glycogen is broken down what does it produce?

A

Glucose-6-Phosphate (cannot be transported across membranes)

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4
Q

What major form of stored fuel is used by the body and why are these the major form?

A

Lipids

-Used as major form as the triglycerides/triacylglycerols can produce six times the amount of energy as glycogen

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5
Q

What is the general structure of triglycerides

A

Esters of glycerol and fatty acids

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6
Q

What is most of the fat in the body stored as?

A

Triglycerides

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7
Q

What is the breakdown of fats called?

A

Lipolysis

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8
Q

Describe the breakdown of triglycerides

A

Lipases digest triglycerides into glycerol and 3 fatty acids.

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9
Q

How are fatty acids broken down and what do they form?

A

Broken down via beta oxidation forming a two carbon acyl unit that combines with Coenzyme A to form Acetyl-Coenzyme A. Although no ATP is formed by this directly, the hydrogen ions and electrons removed by oxidation are passed to the electron transport chain

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10
Q

Fatty acids and glycerol released by adipose tissue are metabolised where?

A

In the liver

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11
Q

The break down of fatty acids occur when?

A

When other fuel sources are not available

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12
Q

The breakdown of fatty acids eventually leads to the formation of what? and name some examples

A

Ketone bodies. Examples include; acetoacetate, 3-hyrdoxybutyrate and acetone

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13
Q

Why do ketone bodies form?

A

Because the acetyl-CoA formed from the breakdown of fatty acids cannot enter the citric acid cycle since oxaloacetate becomes depleted as the liver converts it to pyruvate to form glucose

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14
Q

What happens to unused amino acids

A

They are used as metabolic fuel because the cannot be stored

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15
Q

What happens when amino acids are deaminated?

A

It produces NH4 and a keto acid which are intermediates of the glycolytic pathway or krebs cycle

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16
Q

When amino acids cannot release their amino groups as NH4+, what do they do?

A

They pass their amino group to a keto acid in a process called transamination. This keto acid can then be fed into glycolysis/krebs cycle while the remaining amino acid can be deaminated and used similarly

17
Q

What is the feature of NH4+ that means it is disposed of quickly and how is this done?

A

The group is very toxic so the body very quickly turns it into urea

18
Q

What us Gluconeogenesis

A

The formation of glucose from non-carbohydrate sources

19
Q

What molecules are fed into gluconeogenesis

A

Glycerol from the triglycerates and the carbon back bone from amino acids

20
Q

Where does gluconeogenesis occur?

A

Mostly in the liver

21
Q

What is the most effective fuel?

A

Carbohydrates

22
Q

What fuel sources does the brain use?

A

Normally just glucose but in times of starvation it can use ketone bodies formed in other tissues

23
Q

Why cannot the brain use fatty acids as a fuel source?

A

Because they cannot pass the blood brain barrier

24
Q

Why does the brain require a constant supply of glucose/glycogen?

A

Because it cannot store glucose or glycogen

25
Q

What fuel can the skeletal muscle use?

A

Glucose, fatty acids and ketone bodies

26
Q

How much of the glycogen reserves are found in skeletal muscle/

A

3/4s so a very large amount

27
Q

When muscle protein is broken down what happens to the amino acids?

A

They pass their amino groups (transamination) to pyruvate to form alanine.