Lecture 9: Properties of Muscle Cells and Muscle Contraction

Vocabulary flashcards covering the key terms, definitions, and stages of muscle cell physiology, membrane potentials, and neuromuscular transmission based on Lecture 9 notes.

Excitability

The ability of a cell to respond to a stimulus and generate an electrical signal.

Conductivity

The ability of a cell to conduct electrical changes across the entire plasma membrane.

Contractibility

The ability of a cell to generate tension when stimulated.

Distensibility

The ability of a cell to be stretched without damage.

Elasticity

The ability of a cell to return to its original length after being stretched.

Membrane Potential

An unequal charge distribution across the plasma membrane, characterized by a slightly negative interior inside a resting muscle cell.

Leak Channels

Plasma membrane transport proteins that are always open.

Action Potential

An electrical communication signal defined as a reversal in charge in membrane potential from negative to positive.

Voltage-Gated Channels

Ion channels that open in response to changes in membrane potential.

Depolarization

The stage of an action potential occurring in response to a stimulus during which sodium channels open.

Repolarization

The stage of an action potential during which potassium channels open.

Action Potential Propagation

The process where an action potential spreads down the sarcolemma like a wave, occurring on one part of the sarcolemma at a time.

Synapse

The junction between a neuron and another cell.

Neuromuscular Junction

The synapse between a motor neuron and a muscle fiber.

Axon Terminal

The end of a motor neuron containing vesicles filled with the neurotransmitter acetylcholine.

Acetylcholine (Ach)

The neurotransmitter stored inside vesicles within the axon terminal.

Synaptic Cleft

The narrow space located between the axon terminal and the muscle fiber.

Motor End Plate

The region of the sarcolemma containing ion channels that function as receptors for acetylcholine (Ach).

Excitation Phase

The phase of skeletal muscle contraction occurring at the neuromuscular junction where a signal is transferred from a motor neuron to the sarcolemma.

Excitation-Contraction Coupling

The phase in which events occurring at the neuromuscular junction result in an action potential traveling along the sarcolemma.

Contraction Phase

The phase in which calcium release allows myosin to bind to actin and pull thin filaments closer to the M-line.