Metabolism Flashcards
What is metabolism?
All the chemical reactions in the body
Costs energy
What is anabolism?
Reactions that synthesise new (larger) molecules form precursors
Requires energy
What is catabolism?
Reactions that break down larger molecules into smaller ones
Releases energy
What is post-absorptive stage of metabolism?
maintaining homeostasis between meals
How is ADP transformed to ATP and why?
Extra phosphate stuck to ATP
used to drive other reactions by hydrolysing ATP back to ADP
What is phosphocreatine?
very short term energy store contained in muscle
When a phosphate is removed, ATP and creatine are releases
What is AMP?/
Created from two molecules of ADP, is a marker of a low-energy state
regulates metabolic enzymes allosterically (creates conformational change) - enzymes bind to AMP to enhance their ability to make ATP
ADP + ADP –> ATP + AMP
What powers the Krebs cycle?
Acetyl CoA - so can be powered by amino acids and fatty acids
How can glucose be made from amino acids (proteins)?
Amino acids can power the Krebs cycle, and glucose is made from pyruvate entering the krebs cycle
What is carbohydrate loading?
Trying to maximise stores of glycogen in the muscles and in the liver
Why can’t erythrocytes (RBCs) carry out metabolism?
They lack a nucleus and mitochondria so can’t use the Krebs cycle - no aerobic metabolism
(kind of a good thing because their job is to carry oxygen not use it up)
How do RBCs get energy?
Anaerobic glycolysis
waste pyruvate and lactate go to the liver for gluconeogenesis
What is the average blood plasma glucose concentration?
5-7mM
What do adipocytes store?
Glucose
What signals adipocytes to take up glucose?
insulin
What signals adipocytes to release free fatty acids and glycerol?
glucagon
What is glucose converted to in adipocytes when levels are high?
triglyceride
What is triglyceride metabolised to in adipocytes when glucose?
Free fatty acids and glycerol
How much of cardiac muscle is mitochondria?
up to 40%
Which tissue has lost f myoglobin and what is its role?
cardiac tissue
high affinity for O2, so stores it and releases it when its required
What is the main source of energy for cardiac muscle?
fatty acids - feed into the Krebs cycle
but can also use lactate or ketone bodies
What is type 1 muscle?
slow muscle - skeletal
highly aerobic, lots of mitochondria
adapted to prolonged, modest activity e.g. postural muscles
What is type 2B muscle?
Fast twitch muscle - skeletal
few mitochondria, little/no myoglobin (so its white)
recruited for severe efforts
What is the source of energy for type 1 muscle?
fatty acids - feed into Krebs cycle
