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Musculoskeletal Exam 1 > Biochem - metabolic profile of muscle > Flashcards

Biochem - metabolic profile of muscle Flashcards

1
Q

What type of fibers are slow, oxidative?

A

Type I- red fibers- produce most ATP aerobically- slow to fatigue- maintain prolonged low-intensity contractions
(ex. psoas major- virtually all red fibers) - slow contraction speed - Marathon runners - Endurance

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2
Q

What type of fibers are fast oxidative glycolytic?

A

Type IIa - white fibers - produce most ATP by anaerobic glycolysis- fatigue rapidly - employed in rapid, powerful contractions over shorter periods - Sprinters -

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3
Q

What types of fibers are fast glycolytic?

A

Type IIb - red fibers - intermediate - can produce ATP by both methods - prevalent in muscles involved in regular movement -

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4
Q

What type of energy production is there in cardiac muscle?

What is the preferred substrate?

A
  • Aerobic metabolism, contains many mitochondria and allot of myoglobin. Can use (fatty acids, glucose, ketone bodies, lactate)
    Fatty acids are the preferred substrate
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5
Q

Where is most of the energy for smooth muscle obtained from?

A
  • Glycolysis - therefore less oxidative capacity than cardiac muscle
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6
Q

What is the initial requirement of ATP for contraction supplied by?

A
  • creatine
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7
Q

What is the only energy source that changes greatly in concentration during a muscle contraction?

A

AMP - its levels rise very quickly and activates glycogenolysis (via phosphorylase b) and glycolysis (via PFK-1)

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8
Q

How does creatine kinase work?

What is the rate that it is broken down?

A

It removes a phosphate from phosphocreatine and adds it to ADP forming ATP and Creatine.
- The breakdown of creatine phosphate to creatine is at the same rate no matter what activity level you are doing.

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9
Q

What does ADP and Ca2+ ions activate?

A
  • ADP activates: TCA

- Ca2+ activates glycogenolysis, TCA,

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10
Q

How is there replenishment of ATP when muscle contracts

A

can occur via glycogen breakdown stimulation from AMP, Ca 2+-calmodulin, or protein kinase A.

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11
Q

How does glycogen breakdown occur?

A
  • phosphorylase b changes to phosphorylase a which can occur by:
    1) AMP
    2) Ca2+
    3) Epinephrine during times of stress
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12
Q

What is the deficiency and the physiological results with McArdle’s Disease?

A
  • deficiency (genetic) of muscle glycogen phosphorylase leading to a defect in glycogen breakdown. Symptoms are painful muscle cramps and unusual fatigue on exercise and an inability to produce lactate during exercise.
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13
Q

What is the replaced mechanism of energy production during vigourous exercise in McArdle’s?

A

Rhabdomyolysis

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14
Q

What is primarily responsible for initial activation of PFK-1?

A

AMP

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15
Q

What parts of the TCA cycle do Ca2+ activate? What parts do ADP activate?

A
  • Ca2+ activates:
    1) pyruvate dehydrogenase
    2) isocitrate dehydrogenase
    3) alpha-oxoglutarate dehydrogenase
  • ADP activate
    1) isocitrate dehydrogenase
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16
Q

How can Glut 4 transporters be increased or decreased?

A
  • high glucose levels –> increased insulin levels–> increase in glut 4 movement to cell membrane–> increased glucose transport to cell
  • dec glucose–>dec insulin –> glut 4 transportes removed from surface of the cell
17
Q

What is the main limiting factor in the amount of glycogen stored in muscles?

A

The amounts of glycologen, the excess glucose is converted to fat

18
Q

What are the main site of BCAA metabolism?

A
  • Skeletal muscles
19
Q

What are the main type of metabolism that is used to produce energy in type IIb fibers?

A
  • Produced by lactate produced by anaerobic glycolysis, and glycogen can be mobilized for rapid release of metabolic substrate
20
Q

What types of energy do types I and IIa fibers use?

A
  • most energy produced by oxidative metabolism.
21
Q

What are the advantages of carbohydrate over fat?

A
  • its catabolism can be switched on faster, maximum rate of ATP formation is greater, yields of ATP per oxygen molecule is greater
22
Q

What is the major disadvantage of carbohydrate usage?

A
  • produces about 7 times less energy per gram
23
Q

What is oxygen debt?

A
  • The continued consumption of oxygen after vigorous sustained exercise is over and is due to increasing lactate.
24
Q

What is the main contributor to muscle fatigue?

A
  • Increase in Pi (major contributor)
  • Fall in pH (inhibits PFK-1, inhibits release of Ca2+)
  • Neuromuscular
  • Central fatigue
25
Q

Where are the sources of energy for type I and IIa (red) fibers?

A

catabolize glucose and fats

- source of fats (triacylglcerols- from VLDL and chylomicra, and from free fatty acids)

26
Q

What do Red fibers have a higher level of (as opposed to white fibers) reflecting their greater emphasis on oxidative metabolism?

A

higher levels of FABP and LPL

27
Q

When blood glucose rises, what does it switch on and what is stopped from releasing fat.

A
  • insulin is switched on and lipoprotein lipase is stopped from releasing fat.
28
Q

ACC-2 converts acetyl CoA to malonyl CoA which inhibits the uptake of fats by the mitochondria, why do you have a fat synthesis enzyme present in a tissue that don’t metabolize fat.

A

-AMP-PK inhibits ACC-2 that mediates Acetyl CoA conversion to Malonyl CoA

29
Q

How is Fatty acid uptake into mitochondria regulated?

A
  • AMP stimulates the uptake of fatty acids into the mitochondria by stimulating AMP-PK which inhibits ACC-2 (which would cause Acetyl CoA–>Malonyl CoA) and postively stimulate MCoADC which changes Malonyl CoA (which would normally block Acetyl CoA uptake
30
Q

What are the main sources of energy during starvation for:
the brain
Muscle:

A

the brain and rbc- glucose

Muscle: fatty acid and ketone bodies

31
Q

During starvation what amino acids are released from the liver

A

glutamine and alanine

32
Q

Where does glucagon activate glycogen phosphorylase?

A

Glucagon activates glycogen phosphorylase in the liver NOT THE MUSCLES

33
Q

After 4 hours of starvation what are the main source of fuels?
After 3 weeks what is the main source of fuels?

A
  • Fatty acids

- ketone bodies and fatty acids

34
Q

When is breakdown of muscle protein to provide C atoms for gluconeogenesis (liver) rapid when?
What is it stimulated by?

A
  • days 1-2

- Stimulated by Cortisol

35
Q

What is excess acetyl CoA converted into?

A

Acetoacetate and Beta hydroxybutyrate and acetone

36
Q

In the fed state what are the percentages of fatty acid usage and glucose usage of the cardiac muscle?

A
  • Fatty acids: 60-90% and Glucose: 10-40%
37
Q

What are the 2 sources of energy in the fasted state?

A

Fatty acids and ketone bodies

38
Q

What occurs in the cardiac muscle during ischemic conditions in the cardiac muscle?

A
  • AMP activates AMP-activated protein kinase that phosphorylates PFK-2 (activating it) which enhances production of fructose 2,6 bisphosphate which activates PFK-1

Musculoskeletal Exam 1 (11 decks)

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