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PMVPH > Biochemical Consequences of Protein and Energy Imbalances > Flashcards

Biochemical Consequences of Protein and Energy Imbalances Flashcards

1
Q

What are the 3 major constituents absorbed from the gastrointestinal tract in an omnivore?

A

Glucose
Long chain fatty acids
Amino acids

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2
Q

Which hormone drives storage of products absorbed from the gastrointestinal tract?

A

Insulin

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3
Q

Outline storage of glucose in an omnivore

A

80% stored as muscle glycogen
20% stored as liver glycogen
Excess glucose converted to pyruvate then long chain fatty acids

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4
Q

Give 2 parts of the body that are obligate users of glucose

A

Brain

Red blood cells

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5
Q

Outline the process by which red blood cells get energy…

A

Glycolysis

Obligate anaerobic metabolism

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6
Q

How are triglycerides made?

A

From glycerol and fatty acids

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7
Q

Where are triglycerides made?

A

Adipocytes

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8
Q

How are long chain fatty acids utilised as an energy source?

A

Beta-oxidisation

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9
Q

When might long chain fatty acids be used as an energy source?

A

When glucose is being conserved

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10
Q

How are amino acids stored?

A

Muscle protein
Builds up muscle mass
Source of energy

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11
Q

Outline metabolism of excess amino acids…

A

2 pathways - most can go either way but some are 1 or the other
Glucogenic to pyruvate
Ketogenic to acetyl co-enzyme A

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12
Q

Outline how a carnivore’s metabolism differs from that of an omnivore…

A

Major foodstuff is protein
Metabolism dependent on amino acids
Increased liver metabolism
Glucose made via gluconeogenesis

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13
Q

Outline how glucagon effects the switch to fasting metabolism…

A

Binds to cell surface receptors
Activates G-protein coupled receptor
Activates cAMP which activates protein kinase A
Protein kinase A phosphorylates metabolic hormones to regulate them

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14
Q

What molecule is activated by insulin?

A

Phosphastase

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15
Q

Which hormone initiates the fasting metabolism?

A

Glucagon

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16
Q

In omnivores, why does glycogenolysis occur in fasting?

A

To boost blood glucose

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17
Q

Where does glycogenolysis occur?

A

The liver

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18
Q

In omnivores, what is the classical fasting response to spare glucose?

A

Activation of hormone sensitive lipase
Breakdown of triglycerides
Release of long chain fatty acids into the blood
Tissue with oxygen beta-oxidise long chain fatty acids and use the citric acid cycle for non-toxic energy

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19
Q

What is the byproduct of breakdown of triglycerides, and how is it used in omnivores?

A

Glycerol - goes through gluconeogenesis to boost blood sugar

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20
Q

Outline how muscle storage of amino acids can be used for energy

A

Muscle protein broken down to release amino acids into amino acid pool
Amino acids undergo gluconeogenesis in liver

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21
Q

When is muscle storage of amino acids used as an energy source?

A

Extended fast (last resort as needed for other functions)

22
Q

For how long a fast will omnivore body stores of glycogen last?

A

~1 day

23
Q

For how long a fast will omnivore body stores of triglyceride last?

A

Variable - weeks to months

24
Q

Give an example of a condition inducing perceived starvation

A

Diabetes (lack of insulin causes effective excess of glucagon)

25
Q

Outline the effect of starvation on triglyceride stores

A

Breakdown into long chain fatty acids is upregulated, increasing their concentration in the blood

26
Q

Give the risk associated with beta-oxidation of long chain fatty acids in the liver

A

Ketosis

27
Q

Outline how ketosis occurs

A
  • Beta-oxidisation of long chain fatty acids leads to accumulation of acetyl co-enzyme A
  • Acetyl co-enzyme A use is decreased due to:
    + High cell energy charge (no need for citric acid cycle - turned off allosterically by cell ATP)
    + Depletion of citric acid cycle intermediates (used to make glucose)
  • Build-up of acetyl co-enzyme A by default makes ketone bodies
28
Q

Name the ketone bodies…

A

Acetoacetate
3-hydroxybutyrate
Acetone

29
Q

How is 3-hydroxybutyrate used within the body?

A
  • Oxidised for energy
  • Broken down into 2 acetyl co-enzyme As
  • Acetyl co-enzyme A used in other tissues for citruc acid cycle
  • Important in brain (short chain fatty acids are water soluble and can cross BBB - conserves glucose)
30
Q

Why are ketone bodies useful?

A

Oxidised in tissues for energy

31
Q

Describe ketoacidosis…

A

pH falls due to acidic effect of ketone bodies

32
Q

Give 2 examples of conditions in which ketoacidosis may occur…

A
  • Type 1 diabetes
  • Production diseases
    Twin lamb disease
    Bovine ketosis
33
Q

What is the major product absorbed from the ruminant gastrointestinal tract?

A

Volatile fatty acids (from rumen fermentation)

34
Q

Name the volatile fatty acids

A

Acetate (2 carbons)
Proprionate (3 carbons)
Butyrate (4 carbons)

35
Q

What is butyrate?

A

Volatile fatty acid
4 carbon short chain fatty acid
Ketone body

36
Q

Which volatile fatty acids are converted to acetyl co-enzyme A in ruminant metabolism?

A

Acetate (2 carbons)

Butyrate (4 carbons)

37
Q

How are acetate and butyrate used for energy in ruminant metabolism?

A

Converted to acetyl co-enzyme A

Used in citric acid cycle

38
Q

What is done with excess short chain fatty acids in ruminant metabolism?

A

Conversion to long chain fatty acids

Used in tissue or stored

39
Q

What is the major energy storage product in ruminants?

A

Triglycerides

40
Q

Describe the liver glycogen levels in a ruminant

A

Low

41
Q

Describe ruminant blood sugar

A

Low (about half the level of dogs’)

42
Q

How do ruminants make glucose?

A

From proprionate (gluconeogenesis)

43
Q

How is most ruminant glucose used?

A

Put into blood for essential function

44
Q

Outline prevention of ketoacidosis in high-producing animals

A

Increase concentrates in diet

45
Q

What is the major form of protein fed to ruminants?

A

Heat-treated soybean

46
Q

What is the purpose of heat-treating soybeans in ruminant diets?

A

Harder for rumen microflora to ferment into volatile fatty acids
Protein digested in abomasum and absorbed in small intestine as gluconeogenic substrates

47
Q

Describe the difference between ketoacidosis and rumen acidosis…

A

Ketoacidosis is a fall in the blood pH

Rumen acidosis is a fall in the pH of the rumen contents

48
Q

Why does rumen acidosis occur?

A

Changing diet too quickly leads to lactic acidosis in the rumen

49
Q

What are the outcomes of ketoacidosis?

A

Decreased milk production

Hepatic lipidosis

50
Q

What is the effect of increasing concentrates in the diet of a ruminant?

A

More proprionate absorbed (undergoes gluconeogenesis)

51
Q

When is hepatic lipidosis seen in the ruminant?

A

Ketoacidosis
Starvation
Obesity

PMVPH (11 decks)

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