Muscle Metabolism

Question 1

what accounts for 90% of the energy muscles use?

Answer 1

1 myosin activity

2. ion pumps- maintaining low Ca intracellularly

Question 2

characterize slow twitch muscles

Answer 2

highly vascular
high mitochondria
high muscular triglyceride
glycogen
lipoprotein lipase

Question 3

characterize fast twitch muscles

Answer 3

low vascularization
low mitochondria
high glycolytic enzymes
low muscle triglyceride
lots of glycogen

Question 4

characterize cardiac muscle

Answer 4

very aerobic

highly vascular
high mitochondria
oxidizes fatty acid well
oxidizes lactate well
low capacity for glycolysis
low glycogen

Question 5

what are the local energy stores for muscle?

Answer 5

glycogen
triglyceride (can also get from blood)
ADP
phospho-creatine

Question 6

what are the energy stores muscle gets from blood?

Answer 6

glucose (diet/liver)
fatty acids (adipose)
triglycerides (diet/liver)
ketone bodies (liver)
amino acids (diet)

Question 7

how do muscle cells accept triglyceride from the blood

Answer 7

lipoprotein lipase

Question 8

what are the 2 mechanisms that supply ATP to muscles the quickest?

Answer 8

adenylate kinase- ATP from 2 ADPs

creatine kinase- cleaves phospho-creatine

Question 9

why is AMP important?

Answer 9

activates AMP activated protein kinase- upregulates ATP generation, including fatty acid oxidation

Question 10

/why is glucose the major energy supplier for high intensity workouts

Answer 10

burning fat is a slow process that dominates at low intensity exercises

this is b/c the CAT1 enzyme works slowly and is rate limiting

Question 11

when does “hitting the wall” happen?

Answer 11

when the muscle runs out of glycogen and blood glucose cannot sustain the energy expenditure

happens because CAT is rate limiting, and you cannot access all of your fat

Question 12

what 4 mechanisms are used to maximize ATP use in anaerobic activities

Answer 12

1 adenylate kinase
2 creatine kinase
3 glycogenolysis through PKA independent mechanisms
4. glycolysis activation through allosteric regulation of PFK

Question 13

how is glycogenolysis stimulated?

Answer 13

1 AMP- activates glycogen phosphorylase

2 calcium ions- phosphorylase kinase

Question 14

how does PFK get stimulated during anaerobic activity?

Answer 14

increases of:

1 AMP
2 phosphate
3 ammonia

decreases of

1 ATP
2 creatine phosphate

Question 15

why take protein immediately after exercise?

Answer 15

muscle AMPK has activated maximum glucose uptake via GLUT4 to replenish glycogen stores

Question 16

hypertrophic cardiomyopathy

Answer 16

both environmental and genetic causes, causes enlargement of heart musculature to the point where it is no longer functional

many genetic errors in sarcomeres, and often are dominant

Question 17

what allows the heart to be so good at using lactate as an energy source?

Answer 17

it contains an Lactate dehydrogenase which favorably reconverts back to pyruvate, which can then be metabolized aerobically

Question 18

resting muscle uses mostly what for fuel?

Answer 18

fatty acids

Question 19

benefits of exercise

Answer 19

short term
increased glucose uptake
increased FA oxidation

long term
increased glucose uptake
increased mitochondria
increased mitochondrial activity
increased FA storage in muscle