Neuronal Signaling and the Structure of the Nervous System

Flashcards for reviewing key vocabulary terms related to neuronal signaling and the nervous system's structure.

Central Nervous System (CNS)

Composed of the brain and spinal cord.

Peripheral Nervous System (PNS)

Composed of the nerves that connect the brain or spinal cord with the body’s muscles, glands, and sense organs.

Neuron

The basic cell type of both the central and peripheral nervous systems.

Nuclei

Clusters of cell bodies in the central nervous system.

Glial Cells

The most numerous cells in the central nervous system, providing support and insulation for neurons.

Astrocytes

Support cells in the central nervous system that control the extracellular environment of neurons.

Microglia

Act as the 'immune system' of the central nervous system.

Ependymal Cells

Ciliated cells involved with the production and movement of cerebrospinal fluid (CSF).

Oligodendrocytes

Responsible for myelin formation in the central nervous system.

Satellite Cells

Surround neuron bodies located in the peripheral nervous system.

Schwann Cells

Surround and form myelin sheaths around the larger nerves in the peripheral nervous system.

Afferent Neurons

Send information towards the central nervous system from sensory receptors in the peripheral nervous system.

Efferent Neurons

Send information away from the central nervous system towards axon terminals.

Interneurons

Connect neurons within the central nervous system.

Temporal Summation

Activating one receptor multiple times over a period to increase a signal.

Spatial Summation

Multiple signals coming together to create a larger signal.

Resting Membrane Potential (RMP)

The difference in electrical charge across the plasma membrane when the cell is at rest.

Polarized

The outside and inside of a cell have a different net charge.

Depolarization

The potential moving from resting membrane potential to less negative values.

Repolarization

The potential moving back to the resting membrane potential.

Hyperpolarization

The potential moving away from the resting membrane potential in a more negative direction.

Overshoot

Reversal of the membrane potential polarity where the inside of a cell becomes positive relative to the outside.

Graded Potentials

Changes in membrane potential confined to a small region of the plasma membrane.

Action Potentials

Large, rapid changes in membrane potential that can repeat at high frequencies. They are an 'all or none' response.

Excitability

The ability to generate action potentials.

Ligand-gated Channels

Ion channels that open in response to a chemical stimulus.

Mechanically-gated Channels

Ion channels that open in response to a mechanical stimulus, such as pressure.

Voltage-gated Channels

Ion channels that open or close depending on the membrane potential.

Threshold Potential

The membrane potential at which a cell becomes depolarized enough to generate an action potential.

Absolute Refractory Period

A period during which a second stimulus, no matter how strong, will not produce a second action potential.

Relative Refractory Period

An interval during which a second action potential can be produced, but only if the stimulus strength is considerably greater.

Saltatory Conduction

The process by which action potentials jump from one node of Ranvier to the next in myelinated fibers, speeding up propagation.

Synapses

Junctions between two neurons, which can be electrical or chemical.

Neurotransmitters

Chemicals released from pre-synaptic neurons that bind to receptors on post-synaptic neurons to transmit signals.

Excitatory Postsynaptic Potential (EPSP)

A postsynaptic potential that brings the membrane potential closer to the threshold for generating an action potential.

Inhibitory Postsynaptic Potential (IPSP)

A postsynaptic potential that makes the cell's membrane potential more negative, making it harder to generate an action potential.

Neuromodulators

Modify both the presynaptic and the postsynaptic cell’s response to specific neurotransmitters, amplifying or dampening the effectiveness of ongoing synaptic activity.

Acetylcholine (ACh)

A neurotransmitter found in both the peripheral and central nervous systems.

Catecholamines

Biogenic amine neurotransmitters made from tyrosine, including dopamine, norepinephrine, and epinephrine.

Adrenergic Receptors

Receptors utilized by the neurotransmitters norepinephrine and epinephrine.

Serotonin

A CNS neurotransmitter made from tryptophan involved in regulating sleep, emotions, and other functions.

Histamine

A CNS neurotransmitter made from histidine, commonly known for paracrine actions.

Glutamate

The primary neurotransmitter in 50% of the excitatory synapses in the CNS.

GABA (Gamma-aminobutyric acid)

The major inhibitory neurotransmitter in the brain.

Glycine

A major neurotransmitter released from inhibitory interneurons in the spinal cord and brainstem.

Neuropeptides

Short chains of amino acids with peptide bonds that act as neurotransmitters or neuromodulators.

Gas Neurotransmitters

Neurotransmitters like nitric oxide (NO) that are produced by enzymes in axon terminals and diffuse to other cells.

Purine Neurotransmitters

Nontraditional neurotransmitters including ATP and adenosine, which act principally as neuromodulators.

Forebrain

The anterior part of the brain, including the cerebral hemispheres, thalamus, hypothalamus, and limbic system.

Cerebrum

Consists of the right and left cerebral hemispheres and the diencephalon.

Cerebral Cortex

Divided into four lobes: frontal, parietal, occipital, and temporal.

Thalamus

Relay stations and important integrating centers for most inputs to the cortex.

Hypothalamus

Forms the master command center for neural and endocrine coordination.

Limbic System

Gray and white matter in the forebrain areas associated with learning, emotional experience and behavior, and a wide variety of visceral and endocrine functions.

Hindbrain

Includes the cerebellum, pons, and medulla oblongata.

Brainstem

Receives and integrates input from all regions of the central nervous system and possesses a great deal of neural information.

Reticular Formation

Neuron cell bodies running through the core of the brainstem, involved in motor function, cardiovascular and respiratory control.

Spinal Cord

Lies within the bony vertebral columns and contains gray and white matter.

Peripheral Nervous System

Transmits signals between the CNS and receptors or effector organs.

Somatic Nervous System

Consists of a single neuron between the central nervous system and skeletal muscle cells, leading to muscle excitation.

Autonomic Nervous System

Has a two-neuron chain between the central nervous system and effector organs, innervating smooth and cardiac muscle, glands, and GI neurons.

Sympathetic Nervous System

The 'fight or flight' system, with short pre-ganglionic and long post-ganglionic synapses.

Parasympathetic Nervous System

The 'rest and digest' system, with long pre-ganglionic and short post-ganglionic synapses.

Meninges

The membranes (dura mater, arachnoid mater, and pia mater) that line the structures of the CNS and add additional support and protection.

Cerebrospinal Fluid (CSF)

The extracellular fluid of the CNS that protects and cushions the structures of the brain and spinal cord.

Blood-Brain Barrier

A protective mechanism that helps maintain a stable environment for the brain by separating substances in the brain’s capillaries from the extracellular space.