Electromyography and Myograms Quiz

Electromyography (EMG) and Myograms

• EMG measures electrical activity of muscles
• Myogram records mechanical activity of muscles (contraction/relaxation)
• Refractory Period: A period of time following a stimulus during which a muscle cannot contract again.
• Contraction Period: Time taken for muscle to shorten
• Latent Period: Time between stimulation and muscle contraction
• Relaxation Period: Time for muscle to return to its resting state
• Membrane Potentials in Skeletal Muscle: The electrical potential difference across the muscle cell membrane.
• Reversal of Polarity: A change in electrical charge across the membrane.

Muscle Tension Regulation

• Wave Summation: The increase in muscle tension following successive muscle stimulations.
• Motor Unit Recruitment: Increasing the number of motor units recruited to generate a stronger contraction. Motor recruitment starts by using smaller motor units first, then larger.
• Successive Stimulations: Later stimulations cause greater contractile responses than previous responses.

Neuromuscular Junction

• Axon Terminal: The end of the motor neuron.
• Motor End Plate: The specialized region on the muscle fiber.
• Excitation-Contraction Coupling: The process of transforming the electrical signal into a mechanical contraction.

Sliding Filament Theory

• Z Discs: Move Closer Together
• I Bands: Become Narrower
• Zones of Overlap: Become Wider
• H Zones: Become Narrower
• A Bands: Width Remains Constant
• Tropomyosin: A regulatory protein.
• Calcium: Essential for muscle contraction.
• Troponin: Regulatory protein.
• Power and Recovery Strokes: The cyclical movements of myosin filaments during contraction.

Muscle Contraction Types

• Eccentric Contraction: Muscle lengthens while contracting
• Concentric Contraction: Muscle shortens while contracting
• Isotonic Contraction: Muscle changes its length while contracting

Smooth Muscle Contraction

• Calcium-Calmodulin Complex: Important part of the process.
• Myosin Light-Chain Kinase (MLCK): Enzyme activated by the calcium-calmodulin complex.
• Cross-bridge Phosphorylation: Phosphorylation of myosin light chains.
• ATP Binding and Activity: ATP must bind to the ATPase site for activity.
• Cross Bridge Cycling: The continuous process of the myosin and actin binding and releasing.
• Latch State: A sustained contraction with minimal energy expenditure.
• Phosphorylation: Smooth muscle must be phosphorylated twice to contract.

Smooth Muscle Types

• Single Unit (Visceral) Smooth Muscle: Muscle cells contract together, common in visceral organs.
• Multi Unit Smooth Muscle: Muscle fibers contract independently, common in the eye and other areas needing precision.

Skeletal Muscle Energy

• Glycolysis: An anaerobic process to produce ATP, breaks down glucose to pyruvic acid and possibly lactic acid. Insufficient oxygen leads to lactic acid buildup and decreased muscle function. Glycolysis supplies energy for quick, intense exercise but may be inadequate for prolonged activity.
• Aerobic Respiration: Slowest method for ATP production that breaks down glucose, fatty acids, and amino acids for sustained energy.
• Creatine Phosphate (CP): A high-energy compound to quickly convert ADP to ATP in the resting-phase. Muscle stores can provide energy for approximately 15 seconds of maximal activity.
• Rest and Activity: Lipids for rest, glucose for activity.

Stimulating Skeletal Muscle

• Resting Potential: The electrical charge difference across the muscle membrane at rest.
• Internal Tension: Force produced within the muscle fibers
• External Tension: Force applied by the muscle to the external world