Neurophysiology and Muscle Physiology

Flashcards covering key vocabulary related to neurophysiology and muscle physiology, including nervous system divisions, neuron types, glial cells, ion channels, membrane potentials, and action potential mechanisms.

Neurophysiology

The study of the nervous system's function.

Myophysiology

The study of muscle function.

Excitable Cells

Cells, like neurons and muscle cells, that use action potentials and communicate with one another.

Action Potential

Electrical signal used by excitable cells for communication.

Central Nervous System (CNS)

One of the two major divisions of the nervous system, consisting of the brain and the spinal cord.

Peripheral Nervous System (PNS)

One of the two major divisions of the nervous system, responsible for communicating with the rest of the body.

Neuron

The major cell responsible for nervous system communication

Cell Body

The main part of a neuron containing the nucleus, where information is received and processed.

Axon

A long projection extending from the neuron's cell body,

responsible for sending information to other cells via action potentials.

Myelinated Cell

A nerve cell whose axon is wrapped by another type of cell membrane (myelin sheath).

Schwann Cell

A type of glial cell in the PNS that wraps its membrane around axons, forming myelin.

Myelination

The process where specific glial cells wrap around an axon to provide insulation and increase the speed of electrical signal conduction.

Conduction Velocity

The speed at which an electrical signal (AP) travels along an axon, increased by myelination.

Nerve

In the Peripheral Nervous System, a bundle of many axons traveling along the same path, enclosed by connective tissue.

Tract

In the Central Nervous System, a bundle of many axons traveling along the same path.

Oligodendrocyte

A type of glial cell in CNS that forms myelin around axons, often wrapping around multiple axons.

Glial Cells

Support cells in the nervous system

Astrocytes

Star-shaped glial cells found in the CNS.

Help control the blood-brain barrier, absorb nutrients, and transmit them to neurons.

Blood-Brain Barrier

A protective barrier between the blood and the brain's extracellular fluid, regulated in part by astrocytes, controlling nutrient transmission and vessel constriction.

Ependymal Cells

Glial cells in the CNS that line the ventricles and produce cerebral spinal fluid (CSF).

Cerebral Spinal Fluid (CSF)

A fluid produced by ependymal cells that fills the ventricles in the CNS, cushioning the brain and spinal cord and conveying nutrients.

Microglia

Small, star-shaped glial cells in the CNS that act as immune system cells, protecting against viruses and bacteria.

Interneurons

Neurons, primarily found in the CNS, that connect with other neurons, receiving and transmitting information to other neurons.

Sensory Neuron (Afferent Neuron)

Neurons that bring sensory information from the periphery into the Central Nervous System.

Motor Neuron (Efferent Neuron)

Neurons that convey motor commands out from the Central Nervous System to muscles, glands, or other peripheral neurons.

Sensory Receptor

A specialized ending on a sensory neuron (afferent terminal) that picks up information from the environment, such as pain, temperature, or pressure.

Ion Channels

Integral membrane proteins that allow specific ions to pass through the cell membrane

Ligand-Gated Ion Channel

An ion channel that opens only when a specific signaling molecule (ligand) binds to a receptor on its cell surface.

Voltage-Gated Ion Channel

An ion channel that opens or closes in response to changes in the membrane potential of the cell

Mechanically-Gated Ion Channel

An ion channel that responds to physical forces imposed upon the cell, such as pressure or stretch.

Leak Channels

Ion channels that are either constitutively open or open and close somewhat spontaneously without direct control.

Sodium Concentration Gradient

Intracellular ~15 mM and extracellular ~145 mM, causing sodium to flow into the cell when channels open.

Potassium Concentration Gradient

Intracellular ~150 mM and extracellular ~5 mM, causing potassium to flow out of the cell when channels open.

Chloride Concentration Gradient

Intracellular ~7 mM and extracellular ~100 mM, causing chloride to flow into the cell when channels open.

Membrane Polarization

The difference in electrical charge across the cell membrane, typically negative inside and positive outside at rest.

Resting Membrane Potential

The membrane potential of a cell when it is at rest, typically around -70 mV for many cells.

Depolarization

A decrease in the negativity of the cell's membrane potential (becomes more positive), often caused by the influx of positive ions like sodium.

Hyperpolarization

An increase in the negativity of the cell's membrane potential (becomes more negative), often caused by the efflux of positive ions like potassium.

Graded Potential

Localized changes in membrane potential (depolarization or hyperpolarization) that vary in size and dissipate over distance

Threshold

The specific membrane potential change that must be achieved to trigger an AP

Axon Hillock

a 'little hill' at the beginning of the axon where a graded potential can reach threshold and trigger an action potential.

All-or-Nothing Principle

The rule stating that once the threshold is reached, an AP will fire completely and with the same amplitude, regardless of stimulus strength beyond the threshold.

Inactivation (of sodium channels)

A rapid process where voltage-gated sodium channels close after opening, stopping sodium flow and making them temporarily unable to open again.

Inactivation Gate

A segment of the voltage-gated sodium channel protein structure that moves to close the pore during inactivation.

Refractory State

The period during which an inactivated sodium channel cannot be stimulated to open again.

Sodium-Potassium ATPase

An ion pump that actively transports sodium ions out of the cell and potassium ions into the cell, maintaining or restoring resting membrane potential.

Positive Feedback (sodium channels)

A mechanism where depolarization leads to the opening of voltage-gated sodium channels, causing more sodium influx, which further depolarizes the membrane and opens more sodium channels.

Negative Feedback (potassium channels)

A mechanism where repolarization (due to potassium efflux) feeds back to the potassium channels, helping to move the membrane potential back towards its resting state.