Carbohydrate Metabolism Flashcards

1
Q

What are monosaccharides and what 3 molecules are they?

A

Simplest carbohydrates that are aldehydes or ketones with 2 or more hydroxyl groups

Glucose, fructose and galactose

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2
Q

What are disaccharides and what 3 molecules are they?

A

2 sugars joined by an a-glycosidic bond

Lactose (glucose-galactose)
sucrose (glucose-fructose)
maltose (glucose-glucose)

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3
Q

What are polysaccharides and what molcules are they?

A

2 or more sugars joined by glycosidic bonds eg starch, glycogen and cellulose

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4
Q

What is glycogen?

A

The storage form of glucose

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5
Q

Where in the body is glycogen stored?

A

In the liver and muscle

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6
Q

Where in the cell is glycogen stored?

A

In the cytosol in the form of granules

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7
Q

What do glycogen granules contain and what are they used for?

A

Enzymes for degredation of glycogen (glycogen phosphorylase) and glycogen synthesis (glycogen synthase)

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8
Q

What are the different functions of liver and muscle glycogen?

A

Liver glycogen regulates blood glucose

Muscle glycogen supplies energy

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9
Q

What hormone promotes glycogen synthesis?

A

Insulin

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10
Q

What hormone promotes glycogen breakdown?

A

Glucagon and adrenalin

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11
Q

What are the 5 different fates of glucose when uptaken into cells?

A

Converted to and stored as glycogen in the liver
Metabolized to CO2 and H20 to provide energy
Converted to ketone bodies
Converted to amino acids/proteins
Converted to fat (triglycerides) and stored as adipose tissue

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12
Q

What is glycogenesis?

A

The conversion of glucose to glycogen

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13
Q

What is glycogenolysis?

A

The breakdown of glycogen to glucose

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14
Q

What is gluconeogenesis?

A

The synthesis of glucose from non carbohydrate sources eg amino acids, glycerol, lactate

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15
Q

What is glycolysis?

A

Glucose to pyruvate or lactate

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16
Q

What range are blood glucose levels maintained in?

A

4.4-6.6mM (4.4 before meal, 6.6 after meal)

17
Q

Blood glucose levels are primarily maintained by what organ?

A

The liver

18
Q

Where is insulin synthesized?

A

By the B-cells of the pancreas

19
Q

What does release of insulin stimulate/inhibit?

A

Glycogen synthesis in liver and muscle
Uptake of glucose by muscle and adipose tissue
Stimulates glycolysis in liver (inhibits gluconeogenesis in liver)
Stimulates triglyceride storage in adipose tissue

Overall lowers BG concentrations

20
Q

What enzyme does insulin activate to lower blood glucose levels?

A

Glycogen synthase

21
Q

When is insulin secreted?

A

When blood glucose levels rise

22
Q

Where is glucagon secreted?

A

By the a-cells of the pancreas

23
Q

When is glucagon secreted?

A

In response to low blood glucose levels

24
Q

Glucagon targets what main organ?

A

The liver

25
Q

What does release of glucagon stimulate/inhibit?

A

Glycogenolysis (inhibits glycogenesis)
Gluconeogenesis (inhibits glycolysis)
Inhibits fatty acid synthesis
Stimulates triglyceride breakdown in adipose tissue

Overall increases blood glucose levels

26
Q

Where is adrenalin secreted from?

A

Adrenal medulla and sympathetic nerve endings

27
Q

When is adrenalin secreted?

A

In response to low blood glucose (and stress)

28
Q

What does adrenalin stimulate/inhibit?

A

Stimulates glycogenolysis in muscle and liver
Stimulates glycolysis in muscle
Stimultes triglyceride breakdown in adipose cells