Excitable Tissues: Nerve and Muscle Physiology

These flashcards cover key vocabulary related to the physiology of excitable tissues, specifically nerve and muscle cells.

Excitability

The ability of nerve and muscle cells to respond to stimuli and convert them into nerve impulses.

Action Potential

A rapid rise and fall in the voltage or membrane potential across a cellular membrane.

Neurons

Functional units of the nervous system that transmit information through electrical and chemical signals.

Dendrites

Branch-like structures of a neuron that receive signals from other neurons.

Axon

Long, slender projection of a neuron that conducts electrical impulses away from the neuron's cell body.

Resting Membrane Potential

The voltage difference across the neuronal membrane when the cell is not firing.

Depolarization

Phase in the action potential where there is an influx of sodium ions, making the inside of the neuron more positive.

Repolarization

Phase during which the neuron returns to its resting state after depolarization, often due to potassium ions moving out.

Hyperpolarization

A state during which the membrane potential becomes more negative than the resting membrane potential.

Nerve Fiber

A thread-like extension of a neuron that transmits signals.

Refractory Period

Period after an action potential during which a neuron is less excitable and cannot fire again immediately.

Myelinated Fibers

Nerve fibers that are covered in myelin sheath, allowing for faster transmission of impulses.

Nodes of Ranvier

Gaps in the myelin sheath where action potentials can be regenerated, facilitating quicker signal transmission.

All-or-None Law

Principle stating that a neuron either fires completely or not at all, depending on whether the stimulus reaches threshold.

Chronaxie

Time required to elicit a response in a nerve fiber using a stimulus of double the strength of the threshold stimulus.

Propagation of Action Potential

The process by which an action potential travels along the length of an axon.

Peripheral Nervous System (PNS)

The part of the nervous system outside the brain and spinal cord, including all peripheral nerves.

Central Nervous System (CNS)

Consists of the brain and spinal cord, responsible for processing information and coordinating responses.