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Nervous System and Nervous Tissue - Anatomy & Physiology

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  • Main structures of the nervous system

    The nervous system includes the brain, spinal cord, and nerves.

  • Primary functions of the nervous system

    Sensory detects stimuli, motor initiates responses, and integrative processes information.

  • Two main divisions of the nervous system

    Central nervous system (CNS) includes brain and spinal cord; Peripheral nervous system (PNS) includes all nerves outside CNS.

  • Functional divisions of the peripheral nervous system

    Somatic nervous system controls voluntary movements; Autonomic nervous system controls involuntary functions.

  • Subdivisions of the autonomic nervous system

    Sympathetic division prepares for 'fight or flight'; Parasympathetic division promotes 'rest and digest'.

  • Difference between neuron and neuroglial cell

    Neurons transmit nerve impulses; Neuroglial cells support and protect neurons.

  • Types and locations of neuroglial cells

    Six types: Astrocytes, oligodendrocytes, microglia, ependymal cells (CNS); Schwann cells, satellite cells (PNS).

  • Function of dendrites and axons

    Dendrites receive signals; Axons transmit impulses away from the cell body.

  • Function of the myelin sheath

    Myelin insulates axons and increases the speed of action potential propagation.

  • Structural classifications of neurons

    Neurons can be multipolar, bipolar, or unipolar based on the number of processes.

  • Functional classifications of neurons

    Neurons are classified as sensory (afferent), motor (efferent), or interneurons.

  • Four types of ion channels in neuron membranes

    Leak channels, ligand-gated channels, mechanically gated channels, and voltage-gated channels.

  • Neuron polarization states

    Polarized at rest, depolarized when membrane potential becomes less negative, repolarized returning to rest, hyperpolarized when more negative than rest.

  • Difference between action potential and graded potential

    Action potentials are all-or-none signals; graded potentials vary in magnitude and decay with distance.

  • Typical neuron resting membrane potential

    Approximately \(-70\,mV\).

  • Threshold potential for action potential

    Usually around \(-55\,mV\), the level needed to trigger an action potential.

  • Ions involved in action potential

    Sodium (Na+) and potassium (K+) ions are key; Na+ is higher outside, K+ higher inside at rest.

  • Ion movement during action potential

    Na+ moves into the neuron during depolarization; K+ moves out during repolarization.

  • Refractory period definition

    Time during which a neuron cannot fire another action potential or requires a stronger stimulus.

  • Absolute vs. relative refractory period

    Absolute: no new action potential possible; Relative: action potential possible with stronger stimulus.

  • Saltatory vs. continuous conduction

    Saltatory conduction occurs in myelinated axons jumping between nodes; continuous conduction occurs in unmyelinated axons.

  • Effect of axon diameter on conduction speed

    Larger diameter axons conduct impulses faster due to less resistance.

  • Definition of a synapse

    A junction where a neuron communicates with another cell (neuron, muscle, or gland).

  • Chemical vs. electrical synapse

    Chemical synapses use neurotransmitters; electrical synapses use gap junctions for direct ion flow.

  • How a synapse works

    Action potential triggers neurotransmitter release, which crosses the synaptic cleft and binds receptors on the postsynaptic cell.

  • What is a neurotransmitter?

    A chemical messenger released by neurons to transmit signals across a synapse.

  • Fate of neurotransmitter after synaptic transmission

    Neurotransmitters are broken down by enzymes, reabsorbed by the presynaptic neuron, or diffuse away.