L29

Question 1

what is ATP used for in skeletal muscle

Answer 1

-ATP needed for contraction (for power stroke) AND relaxation (detach myosin head)

Question 2

explain creatine phosphate

Answer 2

• add ADP, can make ATP’
  athletes use creatine to increase creatine phosphate levels, which increases resistance to fatigue

Question 3

explain muscle fatigue

Answer 3

-inability to contract even though muscle is being stimulated
-temporary lack of ATP
- protective mechanisms, so damage can be repaired
-contributing factors
- lactic acid build up
- EC coupling
- damage to SR
- accumulation of K+ in t-tubules

Question 4

explain oxygen debt

Answer 4

• refers to heavy breathing + fast HR after exercise
  -need to replenish O2, ATP, and CP, glycogen
  -conversion of lactic acid to pyruvic acid

Question 5

explain single twitch speed

Answer 5

-varies across muscle
-depends on speed of cross bridge cycling in the fibre

Question 6

explain slow oxidative fibres

Answer 6

• type 1
• slow myosin ATPase isoform produces slow twitches
• needs oxygen
  -dark due to mitochondria, rich blood supply
  -smaller fibre diameters
  -high endurance + fatigue resistance: marathon runners
  -1st type of fibre used when starting exercise

Question 7

explain fast oxidative glycolytic fibres

Answer 7

-type 2a
-fast myosin ATPase isoform produces fast twitches
- needs oxygen
-grey colour
-intermediate fibre diameters
-intermediate endurance + fatigue resistance: weightlifters (need both endurance + HIGH force)
-2nd fibre to be used when starting exercise

Question 8

explain fast glycolytic fibres

Answer 8

-type 2b
-fast myosin ATPase isoform produces fast twitch
-does NOT use oxygen (glycolysis) (aerobic is for endurance, anaerobic is for force)
-few mitochondria + blood supply
-large fibre diameter
- low endurance and fatigue resistance: sprinter
-last fibre to be used when starting exercise

Question 9

what is tetanus

Answer 9

-occurs when a muscle fibre is stimulated so rapidly, not allowed to relax between stimulations, resulting in sustained contraction

Question 10

explain hypertrophy

Answer 10

-muscle mass increases in size with high intensity exercise
-larger size = more sarcomeres = more tension produced per fibre
-type 1 wont hypertrophy, but type 2 may cause needs resistance training

note: satellite cells help repair muscle damage

Question 11

explain muscle atrophy

Answer 11

-when body gets smaller
-can be reversible (sarcopenia, due to aging/di-use), or irreversible (cachexia, due to chronic disease)