Metabolism Flashcards
How do lipids enter the circulatory system?
Through lymphatic system, bypass the liver
Lipids/FFAs are water insoluble. How are they made to be soluble?
Binding FFAs to albumin or other proteins
What are the 4 types of lipoproteins?
Chylomicrons
Very low density lipoprotein
Low density lipoprotein
High density lipoprotei
How are very low density lipoproteins synthesised during the absorptive and post absorptive states?
Absorptive - synthesised from XS glucose
Post absorptive -synthesised from plasma FFA
What are the 2 phases to carnivore/omnivore metabolism?
Absorptive phase - energy derived from oxidation of absorbed nutrients
Post absorptive phase - energy derived from oxidation of stored nutrients
Describe herbivore metabolism compared to carnivore/omniovre
No distinctive phases
Continuous nutrition
The liver takes up nutrients for export to systemic tissues. What does it do with excess nutrients?
Store as lipids or glycogen
What is the insulin:glucagon ratio during the absorptive state?
High
The liver stores glycogen. How much of it’s mass is glycogen? If there is remaining glucose after this point, how is it stored?
5%
Triglycerides
Skeletal muscle stores glucose as glycogen. Why does adipose tissue take up glucose? What happens to excess?
Adipose converts glucose into glycerol for triglyceride synthesis
Excess - stored as VFAs
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?
Liver
Hepatic portal vein
Protein synthesis or conversion to ketone acids
Bypass the liver and enter systemic circulation
The degradation of AAs leads to what compound? Which organs convert it and what do they convert it to? Except in which animals?
NH3
Kidneys and liver convert to urea
Herbivores
Describe urea secretion in herbivores, where it goes and what it is used for
Secreted in saliva
Transferred to forestomach and LI for microbial protein synthesis
What is the insulin : glucagon ratio in the postabsorptive state?
High
How does the liver maintain glucose levels during the post-absorptive state
Glycogenolysis
Gluconeogenesis
How long do the glycogen stores in the liver maintain glucose levels for?
Multiple hours only
Most tissues can derive energy from lipids. Which tissues cannot?
Brain
Erythrocytes
Kidneys
What are the only animals that absorb sufficient glucose from their diet?
Omnivores
Why is glucose essential during pregnancy/lactation
Foetal metabolism
What is gluconeogenesis and where does it take place?
Synthesis of glucose from non-carbohydrat sources
Liver and kidneys
What is the substrate for gluconeogenesis? Which animals are very dependent on this process>
Pyruvate
Herbivores and carnivores
During starvation, what acts as glucose precursors?
Amino acids from skeletal muscle
The glycogen store in skeletal muscle is similar to the liver but can’t do what? What does this mean>
Dephosphorylate glucose phosphate
Cannot be transported into the blood stream
How does skeletal muscle cope with not being able to transport glucose phosphate into the blood stream? What is the process called?
Oxidises pyruvate, liver converts to glucose
Cori cycle
Which hormones regulate carbohydrate metabolism?
Insulin
Glucagon
Adrenaline (stimulates gluconeogenesis)
Glucocorticoids (increased during starvation, used in gluconeogenesis)
WHich hormones regulate protein absorption and in which state of metabolism do they do this?
Insulin - absorptive state
Glucagon - post absorptive state
Which hormones regulate fat metabolism and when do they do this?
Insulin - absorptive state
Glucagon - post absorptive state and during exercise
Ruminants require gluconeogenesis in both post and absorptive phases. What is the insulin: glucagon ratio like?
Low
Remains constant
