Nervous System I: Basic Structure and Function Flashcards

Comprehensive vocabulary flashcards covering the basic structure, cells, signaling, and clinical disorders of the nervous system as presented in Chapter 10.

Sensory function (Sensory input)

The nervous system function that involves detecting changes inside and outside the body via sensory receptors.

Motor output

The nervous system function that stimulates muscles and glands to respond after integration and processing.

Central Nervous System (CNS)

The anatomical division of the nervous system consisting of the brain and spinal cord.

Peripheral Nervous System (PNS)

The anatomical division consisting of cranial nerves and spinal nerves that connects the CNS to other body parts.

Afferent (sensory) division

A subdivision of the PNS that conducts impulses from sensory receptors to the CNS.

Efferent (motor) division

A subdivision of the PNS that transmits impulses from the CNS to effectors like muscles or glands.

Somatic nervous system

A subdivision of the motor division that transmits voluntary commands to skeletal muscles.

Autonomic nervous system

A subdivision of the motor division that transmits involuntary commands to viscera.

Neurons

Nerve cells that respond quickly to stimuli and conduct electrical impulses via neurotransmitters.

Neuroglia

Cells that protect, support, insulate, and nourish neurons but do not conduct electrical impulses.

Cell body (soma or perikaryon)

The part of a neuron containing the nucleus, cytoplasm, organelles, neurofilaments, and chromatophilic substance (Nissl bodies).

Dendrites

Branched receptive surfaces of a neuron that receive information.

Axon

A single process that transmits impulses and releases neurotransmitters to another neuron or effector.

Axon hillock

The cone-shaped area of the cell body from which the axon arises.

Synaptic knob

The rounded ending of a synaptic terminal that releases neurotransmitters.

Myelin

A mixture of fats and proteins that acts as an electrical insulator around some axons.

Nodes of Ranvier

Gaps in the myelin sheath between Schwann cells or Oligodendrocytes.

Tract

A bundle of axons located in the CNS.

Nucleus (as a cluster)

A cluster of neuron cell bodies located in the CNS.

Nerve

A bundle of axons located in the PNS.

Ganglion

A cluster of neuron cell bodies located in the PNS.

White Matter

Groups of myelinated axons in the CNS.

Gray Matter

Groups of unmyelinated axons in the CNS.

Multiple Sclerosis (MS)

A clinical condition involving the destruction of myelin sheaths in the CNS by an immune response, leaving behind scars (scleroses).

Multipolar neurons

Neurons with many processes extending from the cell body (many dendrites, 1 axon); makes up $99\%$ of neurons.

Bipolar neurons

Neurons with two processes (1 dendrite, 1 axon) found in the eyes, ears, and nose.

Unipolar (pseudounipolar) neurons

Neurons with one process extending from the cell body that branches into peripheral and central processes.

Interneurons

Multipolar neurons in the CNS that link other neurons and relay information from one part of the CNS to another.

Astrocytes

Star-shaped CNS neuroglia that connect neurons to blood vessels, form the blood-brain barrier, and regulate ion concentrations like $K^+$.

Oligodendrocytes

CNS neuroglia that produce myelin sheaths for axons in the brain and spinal cord.

Microglia

Phagocytic CNS cells that provide immune protection and structural support.

Ependymal cells

Ciliated cells that line the ventricles of the brain and central canal of the spinal cord to help regulate cerebrospinal fluid.

Schwann Cells

PNS neuroglia that produce myelin sheaths for peripheral axons and support neuronal regeneration.

Satellite Cells

Small cuboidal cells in the PNS that support clusters of neuron cell bodies in ganglia and balance ionic concentrations.

Polarization

The separation of ions across a cell membrane, resulting in a charge or resting membrane potential.

Resting Membrane Potential

The stable voltage in an inactive neuron, typically measured at $-70\,mV$.

Sodium-Potassium ($Na^+/K^+$) Pump

An active transport mechanism that pumps $3\,Na^+$ out and $2\,K^+$ into the cell to maintain ion gradients.

Depolarization

A change in membrane potential in a positive direction (e.g., from $-70\,mV$ to $-62\,mV$) as $Na^+$ ions enter the cell.

Threshold Potential

The critical level to which a membrane potential must be depolarized to initiate an action potential, typically $-55\,mV$.

Action Potential

A sequence of electrical events involving rapid depolarization to approximately $+30\,mV$ followed by repolarization.

Hyperpolarization

A momentary drop in membrane potential below the resting level of $-70\,mV$ at the end of repolarization.

Absolute Refractory Period

The time during which a threshold stimulus cannot generate another action potential because voltage-gated $Na^+$ channels are unresponsive.

Relative Refractory Period

The time when only a high-intensity stimulus can generate another action potential while the membrane is re-establishing its resting potential.

Saltatory conduction

The rapid transmission of impulses in myelinated axons where action potentials 'jump' from one Node of Ranvier to the next.

Synapse

The site where a neuron transmits a nerve impulse to another neuron across a synaptic cleft.

Excitatory postsynaptic potential (EPSP)

A synaptic potential that depolarizes the postsynaptic membrane, making an action potential more likely.

Inhibitory postsynaptic potential (IPSP)

A synaptic potential that hyperpolarizes the postsynaptic membrane, making an action potential less likely.

Summation

The process by which EPSPs and IPSPs are added together at the trigger zone to determine if an action potential will be generated.

Acetylcholine

A neurotransmitter that stimulates skeletal muscle contraction and may excite or inhibit at autonomic nervous system synapses.

Glutamate

The most abundant excitatory neurotransmitter in the CNS.

GABA and glycine

Amino acid neurotransmitters in the CNS that are generally inhibitory.

Substance P

An excitatory neuropeptide involved in the perception of pain.

Enkephalins and endorphins

Generally inhibitory neuropeptides that reduce pain by inhibiting the release of Substance P.

Neuromodulators

Substances that alter a neuron's response to a neurotransmitter or block the release of a neurotransmitter.

Facilitation

The phenomenon where repeated impulses on an excitatory presynaptic neuron increase neurotransmitter release, making the postsynaptic cell more likely to reach threshold.

Neuronal Pools

Groups of interneurons within the CNS that work together to perform a common function.

Convergence

An organization where one neuron receives input from several different neurons, allowing for integration from various sources.

Divergence

An organization where one neuron sends impulses to several neurons, allowing for the amplification of an impulse.

Antagonist

A drug that binds to a receptor and blocks neurotransmitter binding.

Agonist

A drug that activates a receptor, causing an action potential or aiding in neurotransmitter binding.