Lecture 7-Skeletal muscle metabolism Flashcards Preview

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Flashcards in Lecture 7-Skeletal muscle metabolism Deck (16)
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1

What are the three things ATP is needed for in skeletal muscle contraction?

-power stroke

-detachment of myosin from actin

-removal of calcium from the myofibrils into the sarcoplasmic reticulum

2

How is ATP used in the power stroke?

-splitting of ATP by myosin provides energy for the power stroke

3

How is ATP used in the detachment of myosin from actin?

-binding (not splitting) of a fresh ATP molecule to myosin permits detachment of the cross bridge, this ATP is then split and the energy is used for the next power stroke

4

How is ATP used in the removal of calcium from the myofibrils into the sarcoplasmic reticulum?

-active transport of Ca2+ needs ATP

5

What are the three sources of ATP?

-creatine phosphate

-aerobic (citric acid cycle)

-anaerobic (glycolysis)

6

How and when is creatine phosphate used for ATP?

-first energy source tapped into -has high energy phosphate group that can be donated to ADP to form ATP need creatine kinase that brings the phosphate over -used for rapid short bursts of energy

7

How and when is oxidative phosphorylation (aerobic pathway) used for ATP?

-the main source when oxygen present -for longer activity -fueled by glucose derived from muscle glycogen stores or by glucose and fatty acids delivered by the blood -can go on for hours -yields 35 ATPs fro one glucose -fat metabolism (the fatty acids)

8

What does the aerobic pathway consist of?

-citric acid cycle -oxidative phosphorylation -electron transport chain

9

How and when is glycolysis used for ATP?

-main source when oxygen not present -pyruvate (the end product) is converted into lactate (lactic acid)when lack of oxygen prevents the pyruvate from entering the aerobic pathway -used for fast short burst of activity, goes before aerobic (citric acid) -supplies 2 ATP per glucose

10

When do we use which energy source?

-first creatine phosphate (the first 2 mins) -anaerobic (mainly in the first 4 mins) -aerobic (starts 2 mins in) -fat metabolism (8mins)

11

Why is O2 important in ATP production?

-limiting in maximum exertion -need good circulation for oxygen to get there, depends on the heart, blood pressure - respiratory function -local factors= muscle capillaries

12

Why do we have fatigue?

-accumulation of lactic acid -accumulation of inorganic phosphate (from the creatine) -depletion of fuel sources -psychological fatigue -neuromuscular fatigue -oxygen debt

13

What is myoglobin needed for?

-primary oxygen carrying protein in muscle tissue

14

What are types the two oxidative types of muscle fibres?

-slow twitch (I) –appears red -fast twitch IIa – appears red

15

What are the two types of glycolytic muscle fibres?

-fast twitch IIx –appears white -fast twitch IIb –appears white

16

Why is creatine kinase important?

-the enzyme that catalyses the reaction: