Metabolism Flashcards

1
Q

How do lipids enter the circulatory system?

A

Through lymphatic system, bypass the liver

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2
Q

Lipids/FFAs are water insoluble. How are they made to be soluble?

A

Binding FFAs to albumin or other proteins

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3
Q

What are the 4 types of lipoproteins?

A

Chylomicrons
Very low density lipoprotein
Low density lipoprotein
High density lipoprotei

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4
Q

How are very low density lipoproteins synthesised during the absorptive and post absorptive states?

A

Absorptive - synthesised from XS glucose

Post absorptive -synthesised from plasma FFA

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5
Q

What are the 2 phases to carnivore/omnivore metabolism?

A

Absorptive phase - energy derived from oxidation of absorbed nutrients
Post absorptive phase - energy derived from oxidation of stored nutrients

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6
Q

Describe herbivore metabolism compared to carnivore/omniovre

A

No distinctive phases

Continuous nutrition

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7
Q

The liver takes up nutrients for export to systemic tissues. What does it do with excess nutrients?

A

Store as lipids or glycogen

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8
Q

What is the insulin:glucagon ratio during the absorptive state?

A

High

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9
Q

The liver stores glycogen. How much of it’s mass is glycogen? If there is remaining glucose after this point, how is it stored?

A

5%

Triglycerides

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10
Q

Skeletal muscle stores glucose as glycogen. Why does adipose tissue take up glucose? What happens to excess?

A

Adipose converts glucose into glycerol for triglyceride synthesis
Excess - stored as VFAs

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11
Q

Which organ keeps AAs at a steady systemic level? Which vein takes this up? What are the majority of AAs used for? What happens to some AAs?

A

Liver
Hepatic portal vein
Protein synthesis or conversion to ketone acids
Bypass the liver and enter systemic circulation

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12
Q

The degradation of AAs leads to what compound? Which organs convert it and what do they convert it to? Except in which animals?

A

NH3
Kidneys and liver convert to urea
Herbivores

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13
Q

Describe urea secretion in herbivores, where it goes and what it is used for

A

Secreted in saliva

Transferred to forestomach and LI for microbial protein synthesis

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14
Q

What is the insulin : glucagon ratio in the postabsorptive state?

A

High

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15
Q

How does the liver maintain glucose levels during the post-absorptive state

A

Glycogenolysis

Gluconeogenesis

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16
Q

How long do the glycogen stores in the liver maintain glucose levels for?

A

Multiple hours only

17
Q

Most tissues can derive energy from lipids. Which tissues cannot?

A

Brain
Erythrocytes
Kidneys

18
Q

What are the only animals that absorb sufficient glucose from their diet?

19
Q

Why is glucose essential during pregnancy/lactation

A

Foetal metabolism

20
Q

What is gluconeogenesis and where does it take place?

A

Synthesis of glucose from non-carbohydrat sources

Liver and kidneys

21
Q

What is the substrate for gluconeogenesis? Which animals are very dependent on this process>

A

Pyruvate

Herbivores and carnivores

22
Q

During starvation, what acts as glucose precursors?

A

Amino acids from skeletal muscle

23
Q

The glycogen store in skeletal muscle is similar to the liver but can’t do what? What does this mean>

A

Dephosphorylate glucose phosphate

Cannot be transported into the blood stream

24
Q

How does skeletal muscle cope with not being able to transport glucose phosphate into the blood stream? What is the process called?

A

Oxidises pyruvate, liver converts to glucose

Cori cycle

25
Which hormones regulate carbohydrate metabolism?
Insulin Glucagon Adrenaline (stimulates gluconeogenesis) Glucocorticoids (increased during starvation, used in gluconeogenesis)
26
WHich hormones regulate protein absorption and in which state of metabolism do they do this?
Insulin - absorptive state | Glucagon - post absorptive state
27
Which hormones regulate fat metabolism and when do they do this?
Insulin - absorptive state | Glucagon - post absorptive state and during exercise
28
Ruminants require gluconeogenesis in both post and absorptive phases. What is the insulin: glucagon ratio like?
Low | Remains constant