Muscle fibre anatomy / types / coupling

Question 1

what is the thick filament

Answer 1

myosin

Question 2

what is the thin filament

Answer 2

actin

Question 3

which lines (ends of sarcomeres) come closer together in contraction

Answer 3

Z lines

Question 4

which fibre type is used for walking

Answer 4

type 1 - slow oxidative

Question 5

which fibre type is used for fast walking

Answer 5

type IIA - fast, oxidative, fatigue resistant

Question 6

which fibre type is used for jogging

Answer 6

type IIB - fast, oxidative-glycolytic, fatiguable

Question 7

which fibre type is used for sprinting

Answer 7

type IIB - fast, glycolytic, fatiguable

Question 8

what is the difference between darker and lighter fibres

Answer 8

darker = more myoglobin = slower = more oxidative / aerobic

Question 9

why are fibre types evenly distributed in the muscle

Answer 9

to produce even muscle contractions and reduce offset torque on tendons (safer)

Question 10

describe type 1 fibres in terms of force, energy, fatigue, and recovery

Answer 10

less force production
less energy required
slow fatigue
fast receovery (30 sec)

Question 11

describe type IIB fibres in terms of force, energy, fatigue, and recovery

Answer 11

more force production
more energy required
fast fatigue
slow recovery (days)

Question 12

which fibre types contain the most / least myoglobin

Answer 12

type I = most myoglobin (darkest)
type IIB = least myoglobin (lightest)

Question 13

how does calcium get released to start excitation - contraction coupling

Answer 13

AP travels through sarcolemma to t-tubules and calcium is released from the sarcoplasmic reticulum

Question 14

what are the 4 steps of excitation - contraction coupling

Answer 14

1. calcium binds with troponin
2. moves tropomyosin aside
3. actin-myosin binding site exposed
4. power strokes triggered and muscle shortens