Lab Exam: Muscular Physiology Flashcards
1
Q
What is a EMG?
A
- electromyography
- measures the electrical activity of the muscle at the skin surface
- can indicate if a muscle is activated or relaxed
2
Q
How can we use a EMG?
A
- athletes
- work-related issues
- injury prevention/detection
3
Q
With increased contraction =
A
increased electrical activity
4
Q
What are the phases of a muscle twitch?
A
- latent period
- contraction phase
- relaxation phase
5
Q
Describe the latent period.
A
excitation-contraction coupling events
6
Q
Describe the contraction phase.
A
- calcium release
- contraction of muscle fibres
- force generated
7
Q
Describe the relaxation phase.
A
- muscle relaxation
- calcium reuptake
8
Q
Describe the steps of excitation-contraction coupling.
A
- stimulus to contract from the SNS (voluntary)
- signal arrives via motor neuron to muscle fibres
- neuromuscular junction releases neurotransmitter Ach
- Ach stimulates Na+ and K+ channels
- electrical signal passed to muscle fibre
- AP travels along the muscle fibre and reaches t-tubules
- arrival stimulates the calcium receptors to release Ca 2+ from the SR
- Ca2+ binds to proteins on actin (troponin, tropomyosin)
- cross-bridge forms (ATP, ADP, Pi)
- force is generated
9
Q
What are the 2 contraction types?
A
- isometric
- isotonic
10
Q
Describe isometric contraction.
A
no change in muscle length with force generation
11
Q
Describe isotonic contraction.
A
change in muscle length with force generation
12
Q
What are the 2 phases of isotonic contraction?
A
- eccentric
- concentric
