CHAPTER 7: The Nervous System - Vocabulary Flashcards

Vocabulary flashcards covering key terms from chapter notes on the nervous system, neurons, neuroglia, electrical activity, synapses, and neurotransmitters.

Nervous System

Controls thoughts, actions, and emotions; communicates by electrical and chemical signals; 3 functions: sensory input, integration, motor output.

Sensory input

Nervous system function that monitors changes via receptors.

Integration

Processes and interprets sensory inputs to decide how and when to act.

Motor output

Activation of effector organs (muscles and glands) to cause a response.

Central nervous system (CNS)

Brain and spinal cord; integrative and control centers.

Brain

CNS structure that serves as an integrative center.

Spinal cord

CNS structure that transmits information to and from the body.

Peripheral nervous system (PNS)

Nerves, ganglia, outside of the CNS.

Spinal nerves

Nerves carrying impulses to and from the spinal cord (PNS).

Cranial nerves

Nerves carrying impulses to and from the brain (PNS).

Ganglia

Collections of neuron cell bodies outside the CNS.

Afferent division (sensory division)

Carries signals from receptors to the CNS.

Somatic sensory division

Carries signals from receptors in the skin, muscles, bones, and joints.

Visceral sensory division

Carries signals mainly from the viscera of thoracic and abdominal cavities.

Efferent division

Carries signals from the CNS to glands and muscle cells (effector organs).

Somatic motor division

Carries signals from the CNS to skeletal muscles; voluntary.

Autonomic nervous system (ANS)

Visceral motor neurons to glands, cardiac, and smooth muscle; unconscious reflexes.

Sympathetic division

Mobilizes body for action (fight–flight).

Parasympathetic division

Calms the body; rest–digest functions.

Interneuron

Multipolar neuron located entirely within the CNS; analyzes inputs.

Sensory neuron (afferent neuron)

Transmits impulses from a sensory receptor to the CNS.

Motor neuron (efferent neuron)

Transmits impulses from the CNS to an effector organ (muscle/gland).

Nerve

Cable-like collection of many axons in the PNS; may be mixed (sensory and motor fibers).

Somatic motor nerve

Nerve that stimulates contraction of skeletal muscles.

Autonomic motor nerve

Nerve that stimulates contraction or inhibition of smooth/cardiac muscle and glands.

Ganglion

Grouping of neuron cell bodies located outside the CNS.

Nucleus

Grouping of neuron cell bodies within the CNS.

Tract

Grouping of axons that interconnect regions of the CNS.

Neuron

Nerve cell; basic unit of the nervous system.

Cell body (soma)

Contains organelles necessary to sustain neuronal life.

Dendrites

Receptive/input regions; carry signals toward the cell body.

Axon

Conductive/output region; carries signals away from the cell body.

Axon hillock

Cone-shaped initial segment of the axon.

Terminal branches (arborizations)

Branches at the end of the axon; contain axon terminals.

Axon terminals

Knob-like distal end of terminal branches; release neurotransmitters.

Neurotransmitter

Chemical signal used to signal the next cell at the synapse.

Anterograde transport

Movement down the axon away from the soma.

Retrograde transport

Movement up the axon toward the soma.

Multipolar neuron

One axon and multiple dendrites; most common type.

Bipolar neuron

Two processes (one axon, one dendrite); found in special senses.

Unipolar neuron

Single process from the soma; sensory from skin/organs to CNS.

Anaxonic neuron

Many dendrites, no distinguishable axon; found in some CNS interneurons.

Interneurons (association neurons)

Analyze inputs and coordinate outputs between sensory and motor neurons.

Motor neurons

Conduct impulses from the CNS to target organs.

Neuroglia (glial cells)

Non-conductive cells that support neurons; include several types.

Astrocyte

Form the blood-brain barrier; regulate extracellular environment and development.

Blood-brain barrier

Selective barrier formed by astrocytes to protect CNS.

Microglial cells

Phagocytic CNS macrophages; protect CNS by engulfing harmful agents.

Ependymal cells

Line ventricles; produce and circulate cerebrospinal fluid (CSF).

Oligodendrocytes

Form myelin sheaths around CNS axons; white matter.

Schwann cells (neurolemmocytes)

Form myelin around PNS axons; surround all PNS axons.

Satellite glial cells

Support neurons within sensory and autonomic ganglia in the PNS.

Myelin sheath

Insulates axons; speeds transmission; produced by oligodendrocytes in CNS and Schwann cells in PNS.

Nodes of Ranvier

Gaps in the myelin sheath between Schwann cells that facilitate rapid conduction.

Demyelinating diseases

Diseases where myelin sheaths are attacked.

Guillain–Barré syndrome

Autoimmune attack on PNS myelin causing rapid muscle weakness.

Multiple sclerosis (MS)

Autoimmune attack on CNS myelin causing demyelination.

Regeneration tube

Schwann cell–formed structure guiding axon regrowth in the PNS.

Nogo

Inhibitory protein from oligodendrocytes that prevents CNS axon regeneration.

Neurotrophins

Proteins that aid regeneration of neurons.

Resting membrane potential

Stable membrane potential of a neuron at rest (~−70 mV).

Polarized

State with a membrane potential difference (inside negative).

Depolarization

Membrane becomes more positive; influx of Na+; excitatory. (

Repolarization

Return to resting potential; Na+ channels reset; K+ exits.

Hyperpolarization

Inside becomes more negative; inhibitory; K+ leaves or Cl− enters.

Threshold

Membrane potential (-55 mV) required to trigger an action potential.

Action potential

Rapid, self-propagating electrical impulse along the axon.

Propagation

Spread of the action potential along the axon.

Refractory period

Time when neuron cannot fire another AP; absolute and relative types.

Absolute refractory period

Na+ channels are inactivated; no new AP can be triggered.

Relative refractory period

Most Na+ channels reset; some K+ channels open; stronger stimulus needed.

Synapse

Functional connection between a neuron and its target cell; electrical or chemical.

Presynaptic

Neuron signaling at the synapse (sender).

Postsynaptic

Neuron or cell receiving the signal.

Electrical synapse

Gap junction–mediated synapse; current flows directly between cells.

Chemical synapse

Synapse that uses neurotransmitters to signal across the synaptic cleft.

Synaptic knob (end bulb)

Presynaptic terminal end containing neurotransmitter vesicles.

Exocytosis

Release of neurotransmitters from vesicles into the synaptic cleft.

Synaptic cleft

Narrow space between presynaptic and postsynaptic cells.

Neurotransmitter receptors

Postsynaptic receptors that bind neurotransmitters.

Ligand-gated channels

Ion channels opened directly by neurotransmitter binding.

G-protein coupled channels

Ion channels opened indirectly via G-protein signaling.

IPSP (inhibitory postsynaptic potential)

Hyperpolarizing postsynaptic potential reducing likelihood of AP.

EPSP (excitatory postsynaptic potential)

Depolarizing postsynaptic potential increasing likelihood of AP.

Monoamines

Regulatory neurotransmitters derived from amino acids (e.g., dopamine, norepinephrine, epinephrine, serotonin, histamine).

Catecholamines

Dopamine, norepinephrine, and epinephrine.

MAO inhibitors

Drugs that block monoamine oxidase, increasing monoamine levels.

cAMP

Cyclic adenosine monophosphate; a common second messenger.

Protein kinase

Enzyme activated by cAMP that phosphorylates proteins.

Dopamine

Monoamine involved in motor control, reward; excess linked to schizophrenia; Parkinson’s disease involves loss of dopaminergic neurons.

Norepinephrine

Monoamine used in CNS and PNS; arousal in brain; sympathetic pathways use it.

Epinephrine

Also called adrenaline; catecholamine involved in fight–flight responses.

Serotonin

Monoamine involved in mood, behavior, and arousal; SSRIs treat depression.

GABA (gamma-aminobutyric acid)

Major inhibitory neurotransmitter in the brain.

Glutamate

Major excitatory neurotransmitter; involved in memory storage.

Neuropeptides

Neuromodulators such as cholecystokinin, substance P, endorphins, neuropeptide Y.

Cholecystokinin

Neuropeptide involved in satiety after a meal.

Substance P

Neuropeptide that mediates pain sensation.

Endorphins

Endogenous opioids; pain relief and euphoria.

Neuropeptide Y

Neuropeptide involved in stress response and circadian rhythms.