Neurophysiology Outline

These flashcards cover key vocabulary and concepts found in the lecture on neurophysiology, including the structure and function of the nervous system, the mechanisms of synaptic transmission, and the principles governing action potentials.

Sensory Nervous System

The part of the nervous system that receives sensory input from both the internal and external environment.

Somatic Sensory

Sensory input that is consciously perceived, such as touch and pain.

Visceral Sensory

Sensory input that is not consciously perceived, such as internal organ sensations.

Motor Nervous System

Part of the nervous system that transmits motor commands to effectors.

Somatic Motor

Motor control that is conscious and voluntary.

Autonomic Motor

Motor control that is unconscious and involuntary.

Neuroglial Cells

Supportive cells in the nervous system that provide assistance to neurons.

Oligodendrocytes

Type of neuroglial cell that forms myelin sheath in the central nervous system.

Astrocytes

Star-shaped neuroglial cells that support neurons and maintain the blood-brain barrier.

Ependymal Cells

Neuroglial cells that line the ventricles of the brain and produce cerebrospinal fluid.

Microglia

Immune cells of the central nervous system that remove waste and pathogens.

Schwann Cells

Neuroglial cells that form myelin sheath around axons in the peripheral nervous system.

Satellite Cells

Glial cells that support neuron cell bodies in ganglia.

Neurons

Excitable cells that transmit electrical signals throughout the nervous system.

Dendrites

Branching extensions of neurons that receive signals from other neurons.

Axon

The long projection of a neuron that transmits action potentials away from the cell body.

Myelin Sheath

Wrapper around axons formed by Schwann cells, which increases the speed of signal transmission.

Nodes of Ranvier

Gaps in the myelin sheath where action potentials are regenerated.

Telodendrites

Distal branches of an axon that lead to axon terminals.

Axon Terminals

The endings of axons where neurotransmitters are released.

Synapses

Junctions between neurons or between neurons and target cells.

Presynaptic Neuron

Neuron that sends the signal through the synapse.

Postsynaptic Neuron

Neuron that receives the signal at the synapse.

Synaptic Cleft

The fluid-filled space between the presynaptic and postsynaptic neurons.

Membrane Potential

The voltage difference across a cell membrane due to the separation of charges.

Voltage

The measure of potential energy due to charge separation in a cell.

Ion Channels

Proteins in the cell membrane that allow ions to pass through.

Ligand-gated Channels

Ion channels that open when a neurotransmitter binds to them.

Mechanically gated Channels

Ion channels that open in response to physical forces.

Voltage-gated Channels

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

Leaky Channels

Ion channels that are always open and allow ions to pass freely.

Resting Membrane Potential

The electrical potential difference across the membrane of a resting neuron, typically around -70 mV.

Graded Potential

A localized change in membrane potential that can vary in size.

Action Potential

A brief reversal of the membrane potential that propagates along the axon.

Depolarization

A decrease in membrane potential (making it less negative) that occurs when sodium channels open.

Threshold Potential

The critical level of membrane potential required to initiate an action potential.

Repolarization

Return of the membrane potential to the resting state after an action potential.

Hyperpolarization

An increase in membrane potential making it more negative than resting potential.

Absolute Refractory Period

The period when a neuron cannot generate another action potential, typically during depolarization and repolarization.

Relative Refractory Period

The period after absolute refractory period when a stronger-than-normal stimulus can initiate a new action potential.

Myelination

The process of forming a myelin sheath around axons to increase signal speed.

Saltatory Conduction

The process by which action potentials jump from node to node along a myelinated axon.

Calcium Channels

Voltage-gated channels that open during an action potential, allowing Ca2+ ions to enter the axon terminal.

Neurotransmitters

Chemical messengers that transmit signals across the synapse from one neuron to another.

Excitatory Postsynaptic Potentials (EPSP)

Graded potentials that increase the likelihood of an action potential in the postsynaptic neuron.

Inhibitory Postsynaptic Potentials (IPSP)

Graded potentials that decrease the likelihood of an action potential in the postsynaptic neuron.

Summation

The process by which multiple graded potentials combine to produce a larger change in membrane potential.

Temporal Summation

When a presynaptic neuron fires impulses in rapid succession to create a stronger EPSP.

Spatial Summation

When multiple presynaptic neurons release neurotransmitters simultaneously to create a stronger EPSP.

Presynaptic Inhibition

Decrease in neurotransmitter release from one neuron due to influence from another neuron.

Presynaptic Facilitation

Increase in neurotransmitter release from one neuron due to influence from another neuron.

Acetylcholine (ACh)

A neurotransmitter involved in muscle activation and various brain functions.

Biogenic Amines

Class of neurotransmitters that includes catecholamines and serotonin.

Amino Acids

Building blocks of proteins; some can function as neurotransmitters like glutamate and GABA.

Peptides

Small chains of amino acids that can act as neurotransmitters, such as endorphins.

Diffusion

The process by which neurotransmitters are removed from the synapse by moving away from the site.

Neurotransmitter Receptor

Proteins on the postsynaptic neuron that bind neurotransmitters.

Fast Synapses

Synapses that mediate rapid effects, typically via direct action on ion channels.

Slow Synapses

Synapses that mediate slower, long-lasting effects through second messengers.

Divergent Circuit

A circuit where one incoming fiber stimulates an increasing number of fibers.

Convergent Circuit

A circuit where multiple inputs converge to influence a single neuron.

Reverberating Circuit

A circuit where neurons stimulate each other in a looping manner.

Parallel After-Discharge Circuit

A circuit in which incoming neurons stimulate multiple pathways simultaneously.

Neuroglial Cell Types

Includes oligodendrocytes, astrocytes, ependymal cells, microglia, Schwann cells, and satellite cells.

Cerebrospinal Fluid

Fluid that circulates around the brain and spinal cord, providing cushioning and support.

Nerve Impulse

An electrical signal that travels along a neuron.

Resting Ionic Concentrations

The distribution of ions across a neuron's membrane at rest, primarily Na+ and K+.

Threshold Level

The membrane potential at which voltage-gated channels open to initiate an action potential.

Neurotransmitter Recycling

The process by which neurotransmitters are taken back into the presynaptic neuron for reuse.

Acetylcholinesterase

An enzyme that breaks down acetylcholine in the synaptic cleft.

Catechol-O-methyltransferase

An enzyme that breaks down catecholamines in the circulation.

Mechanisms of Neurotransmitter Deactivation

Includes enzymatic degradation, reuptake by presynaptic terminals, and diffusion away from the synapse.

Chemical Gradient

Difference in ion concentration across a membrane.

Electrical Gradient

Difference in charge across a membrane.

Sodium-Potassium Pump

An active transport mechanism that maintains resting ionic concentrations by moving Na+ out and K+ in.

Excitatory Effects

When neurotransmitter binding makes the postsynaptic membrane depolarize.

Inhibitory Effects

When neurotransmitter binding makes the postsynaptic membrane hyperpolarize.

Action Potential Threshold

The membrane potential that must be reached to initiate an action potential, typically around -55 mV.

Neural Integration

The summation of excitatory and inhibitory signals at the axon hillock to determine the generation of an action potential.

Collaterals

Branches of axons that allow communication with other neurons.

Neural Plasticity

The ability of the nervous system to change and adapt in response to experience.

Dendritic Spine

Small protrusions on dendrites that enhance synaptic transmission.

Long-term Potentiation (LTP)

A persistent strengthening of synapses based on recent patterns of activity.