Metabolism

Question 1

How do lipids enter the circulatory system?

Answer 1

Through lymphatic system, bypass the liver

Question 2

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

Answer 2

Binding FFAs to albumin or other proteins

Question 3

What are the 4 types of lipoproteins?

Answer 3

Chylomicrons
Very low density lipoprotein
Low density lipoprotein
High density lipoprotei

Question 4

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

Answer 4

Absorptive - synthesised from XS glucose

Post absorptive -synthesised from plasma FFA

Question 5

What are the 2 phases to carnivore/omnivore metabolism?

Answer 5

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

Question 6

Describe herbivore metabolism compared to carnivore/omniovre

Answer 6

No distinctive phases

Continuous nutrition

Question 7

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

Answer 7

Store as lipids or glycogen

Question 8

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

Answer 8

High

Question 9

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

Answer 9

5%

Triglycerides

Question 10

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

Answer 10

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

Question 11

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?

Answer 11

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

Question 12

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

Answer 12

NH3
Kidneys and liver convert to urea
Herbivores

Question 13

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

Answer 13

Secreted in saliva

Transferred to forestomach and LI for microbial protein synthesis

Question 14

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

Answer 14

High

Question 15

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

Answer 15

Glycogenolysis

Gluconeogenesis

Question 16

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

Answer 16

Multiple hours only

Question 17

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

Answer 17

Brain
Erythrocytes
Kidneys

Question 18

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

Answer 18

Omnivores

Question 19

Why is glucose essential during pregnancy/lactation

Answer 19

Foetal metabolism

Question 20

What is gluconeogenesis and where does it take place?

Answer 20

Synthesis of glucose from non-carbohydrat sources

Liver and kidneys

Question 21

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

Answer 21

Pyruvate

Herbivores and carnivores

Question 22

During starvation, what acts as glucose precursors?

Answer 22

Amino acids from skeletal muscle

Question 23

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

Answer 23

Dephosphorylate glucose phosphate

Cannot be transported into the blood stream

Question 24

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

Answer 24

Oxidises pyruvate, liver converts to glucose

Cori cycle

Question 25

Which hormones regulate carbohydrate metabolism?

Answer 25

Insulin
Glucagon
Adrenaline (stimulates gluconeogenesis)
Glucocorticoids (increased during starvation, used in gluconeogenesis)

Question 26

WHich hormones regulate protein absorption and in which state of metabolism do they do this?

Answer 26

Insulin - absorptive state

Glucagon - post absorptive state

Question 27

Which hormones regulate fat metabolism and when do they do this?

Answer 27

Insulin - absorptive state

Glucagon - post absorptive state and during exercise

Question 28

Ruminants require gluconeogenesis in both post and absorptive phases. What is the insulin: glucagon ratio like?

Answer 28

Low

Remains constant