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Nervous System Anatomy & Physiology

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Termini in questo insieme (23)

  • What is intracranial regulation (ICR)?

    Intracranial regulation (ICR) refers to mechanisms or conditions that maintain a balance promoting an environment conducive to optimal brain functioning, regulating the contents of the skull including brain, circulatory system, and dura mater.

  • What are the main functions of the nervous system?

    Sensory input: gathering information about internal and external changes.
    Integration: processing and interpreting sensory input.
    Motor output: activating effector organs to produce a response.

  • What are the two main divisions of the nervous system?

    Central nervous system (CNS): brain and spinal cord.
    Peripheral nervous system (PNS): nerves outside CNS, including cranial and spinal nerves.

  • What are the functional divisions of the Peripheral Nervous System (PNS)?

    Sensory (afferent) division: transmits impulses from receptors to CNS.
    Motor (efferent) division: transmits impulses from CNS to effectors; includes somatic (voluntary) and autonomic (involuntary) systems.

  • What are the two principal cell types in nervous tissue?

    Neurons: excitable cells that transmit electrical signals.
    Neuroglia (glial cells): small cells that support and protect neurons.

  • Name four types of CNS neuroglia and their functions.

    Astrocytes: support, blood-brain barrier, homeostasis.
    Microglial cells: immune defense, monitor neuron health.
    Ependymal cells: line cavities, produce cerebrospinal fluid.
    Oligodendrocytes: form myelin sheaths around CNS axons.

  • What are the neuroglia of the PNS and their roles?

    Satellite cells: surround neuron cell bodies.
    Schwann cells: form myelin sheaths around peripheral nerve fibers and aid regeneration.

  • What is the function of the myelin sheath?

    Myelin sheath protects and electrically insulates axons, increasing the speed of nerve impulse transmission.

  • Describe the structure of a neuron.

    Neurons have a cell body (biosynthetic center), dendrites (input regions), and a single axon (conducting region) that transmits impulses to axon terminals.

  • What are the three structural classifications of neurons?

    Multipolar: 3 or more processes.
    Bipolar: 2 processes.
    Unipolar: 1 short process.

  • How are neurons functionally classified?

    Sensory (afferent): transmit impulses to CNS.
    Motor (efferent): carry impulses from CNS to effectors.
    Interneurons: connect sensory and motor neurons within CNS.

  • What is the resting membrane potential of a neuron and what causes it?

    Approximately \(-70\,mV\), caused by ionic differences across the membrane and selective permeability.

  • Define depolarization and hyperpolarization.

    Depolarization: membrane potential becomes less negative, increasing chance of nerve impulse.
    Hyperpolarization: membrane potential becomes more negative, decreasing chance of nerve impulse.

  • What are graded potentials and action potentials?

    Graded potentials: short-distance, variable strength signals.
    Action potentials: long-distance, all-or-none nerve impulses.

  • What is the role of the sodium-potassium pump in neurons?

    Restores ionic conditions after repolarization by pumping Na+ out and K+ into the cell.

  • What is the refractory period in neurons?

    Absolute refractory period: neuron cannot respond to another stimulus.
    Relative refractory period: neuron can respond only to a stronger stimulus.

  • What factors affect conduction velocity of nerve impulses?

    Axon diameter (larger is faster) and degree of myelination (myelinated fibers conduct faster via saltatory conduction).

  • What is a synapse?

    A junction where neurons communicate with other neurons or effector cells, either electrically or chemically.

  • Differentiate electrical and chemical synapses.

    Electrical synapses: direct cytoplasmic connections via gap junctions, fast but less common.
    Chemical synapses: use neurotransmitters to transmit signals across synaptic clefts.

  • What are neurotransmitters and how are they classified chemically?

    Chemical messengers of the nervous system; classified as biogenic amines, amino acids, purines, peptides, endocannabinoids, gases, and acetylcholine.

  • How do neurotransmitter receptors function?

    Channel-linked receptors: direct, fast synaptic transmission.
    G protein-linked receptors: indirect, slow synaptic responses.

  • What is serial processing in neural circuits?

    Input travels along one pathway to produce a specific, all-or-none response, such as spinal reflexes.

  • What is parallel processing in neural circuits?

    Input travels along multiple pathways simultaneously, allowing different responses to the same stimulus, important for higher mental functions.