skeletal muscle

Question 1

structure of skeletal muscle

Answer 1

Actin and myosin filaments
actin slides over myosin forming cross-bridges
A band (darker)
I band (lighter)
titin helps maintain structure of sarcomere
muscle contains afferent sensors that sense the stretch of a muscle

Question 2

neurotransmitter that changes voltage of muscles

Answer 2

acetylcholine

Question 3

describe the cross-bridge cycle

Answer 3

calcium released which removes tropomyosin from blocking binding site allowing cross-bridge to form between actin and myosin
cross-bridge moves in power stroke by hydrolysis of ATP
cross-bridge then unbinds by ATP to disconnect actin and myosin
process repeats

Question 4

what is the frequency tension relationship?

Answer 4

increased frequency of stimulation causes twitches to get larger (temporal summation)

Question 5

fuels used for muscle contraction

Answer 5

-creatine phosphate mechanism- provides energy quickly from ATP but only lasts 1-2 seconds
-gycolysis mechanism- energy from glucose (anaerobic)
-oxidative phosphorylation- energy from glucose or fat (aerobic)

Question 6

what are the three muscle fibre types?

Answer 6

type IIx- fast twitch glycolytic fibres
type IIa- fast oxidative glycolytic fibres
type I- slow oxidative

Question 7

what are the differences between type I and type II muscle fibres

Answer 7

the primary mechanisms that are used to produce ATP
the type of motor unit innervation
the type of myosin heavy chain expressed