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Fundamentals of the Nervous System and Nervous Tissue

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Terms in this set (23)

  • Three basic functions of the nervous system

    Sensing changes (sensory), interpreting changes (integrative), and reacting to changes (motor).

  • Central nervous system (CNS) components

    The brain and spinal cord.

  • Peripheral nervous system (PNS) components

    Cranial and spinal nerves with sensory (afferent) and motor (efferent) components.

  • Somatic nervous system (SNS) function

    Conducts impulses from skin and special senses to CNS and from CNS to skeletal muscle (voluntary control).

  • Autonomic nervous system (ANS) function

    Conveys impulses from CNS to smooth muscle, cardiac muscle, and glands (involuntary control).

  • Role of astrocytes in CNS

    Anchor neurons to capillaries, help form the blood-brain barrier, and recapture neurotransmitters.

  • Function of oligodendrocytes

    Wrap cytoplasmic extensions to form myelin sheaths around CNS nerve fibers.

  • Microglia role

    Act as macrophages engulfing microorganisms and dead neural tissue in the CNS.

  • Schwann cells function in PNS

    Form myelin sheaths around PNS nerve fibers and act as phagocytes.

  • Basic structure of a neuron

    Consists of a cell body (soma), dendrites (input), and usually a single axon (output).

  • Classification of neurons by structure

    Multipolar: many dendrites, one axon; bipolar: one dendrite, one axon; unipolar: one fused process.

  • Classification of neurons by function

    Afferent (sensory): impulses to CNS; association (interneurons): impulses between neurons; efferent (motor): impulses to effectors.

  • Difference between gray and white matter

    White matter: myelinated axons; gray matter: nerve cell bodies, dendrites, unmyelinated axons, and neuroglia.

  • Types of ion channels in neurons

    Leakage (nongated) channels always open; gated channels open/close in response to stimuli (voltage, chemical, mechanical, light).

  • Resting membrane potential value and cause

    Typically -70 mV, caused by ion distribution: more positive sodium ions outside, more negative ions and proteins inside.

  • Action potential phases

    Depolarization: membrane potential reverses (+30 mV); repolarization: returns to resting potential (-70 mV) via sodium-potassium pumps.

  • All-or-none principle of action potentials

    If threshold is reached, an action potential fires at constant maximum strength; stronger stimuli do not increase impulse size.

  • Saltatory conduction

    Action potentials jump between myelin-covered nodes, speeding impulse conduction in myelinated fibers.

  • Excitatory postsynaptic potential (EPSP)

    A depolarizing postsynaptic potential that makes the neuron more likely to reach threshold and fire an action potential.

  • Inhibitory postsynaptic potential (IPSP)

    A hyperpolarizing postsynaptic potential that makes the neuron less likely to fire an action potential.

  • Neurotransmitter removal methods

    Removed from synaptic cleft by diffusion, enzymatic degradation, or uptake into neurons and glia.

  • Neuronal regeneration in PNS

    Possible if cell body intact and Schwann cells active; involves Wallerian degeneration and Schwann cell-guided regrowth.

  • Neuronal regeneration in CNS

    Usually permanent damage; CNS neurons generally do not regenerate after injury.