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Fundamentals of the Nervous System and Nervous Tissue - Anatomy & Physiology

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Termini in questo insieme (29)

  • What are the two principal parts of the nervous system?
    Central nervous system (CNS) - integration and control center; Peripheral nervous system (PNS) - mainly nerves extending from brain and spinal cord.
  • What are the main functions of the nervous system?
    To receive sensory input, integrate information, and produce motor output to respond to stimuli.
  • What are neuroglia and neurons?
    Neuroglia are small cells that support and protect neurons; Neurons are excitable cells that transmit electrical signals.
  • Name the four main types of neuroglia in the CNS.
    Astrocytes, Microglial cells, Ependymal cells, Oligodendrocytes.
  • What is the function of astrocytes?
    Support neurons, regulate chemical environment, guide neuron migration, recycle neurotransmitters, and maintain blood-brain barrier.
  • What role do microglial cells play in the CNS?
    Act as defensive cells by monitoring neurons and phagocytizing microorganisms and debris.
  • What are ependymal cells and their function?
    Ciliated cells lining CNS cavities that circulate cerebrospinal fluid and form a permeable barrier.
  • What is the role of oligodendrocytes?
    Wrap CNS nerve fibers with myelin sheath to insulate and speed up electrical impulses.
  • What are the two major neuroglia in the PNS?
    Satellite cells (surround neuron cell bodies) and Schwann cells (form myelin sheaths around peripheral nerve fibers).
  • What are the special characteristics of neurons?
    Extreme longevity, amitotic (mostly), high metabolic rate requiring oxygen and glucose.
  • What is the function of dendrites in neurons?
    Receptive regions that receive signals and convey graded potentials toward the cell body.
  • Describe the structure and function of an axon.
    Single long process that generates and transmits action potentials away from the cell body to axon terminals.
  • What is the myelin sheath and its function?
    A white fatty insulating layer around axons that protects and increases speed of nerve impulse transmission.
  • How is myelin formed in the PNS and CNS?
    In PNS by Schwann cells wrapping axons; in CNS by oligodendrocyte processes wrapping multiple axons.
  • What are the three structural classes of neurons?
    Multipolar (many dendrites, one axon), Bipolar (one dendrite, one axon), Unipolar (single process dividing into two branches).
  • What are the three functional classes of neurons?
    Sensory (afferent), Motor (efferent), and Interneurons (association neurons).
  • What is resting membrane potential in neurons?
    The voltage difference across the membrane at rest, approximately -70 mV, with the inside negative relative to outside.
  • What ion plays the most important role in generating resting membrane potential?
    Potassium (K+) due to its higher permeability and concentration gradient.
  • What are graded potentials?
    Short-lived, localized changes in membrane potential that can be depolarizing or hyperpolarizing.
  • What is an action potential?
    A brief, large depolarization (~100 mV) that propagates along the axon to transmit signals over long distances.
  • Describe the four main phases of an action potential.
    Resting state, Depolarization (Na+ channels open), Repolarization (Na+ channels inactivate, K+ channels open), Hyperpolarization (K+ channels remain open).
  • What is the all-or-none phenomenon in action potentials?
    An action potential either occurs fully when threshold is reached or does not occur at all.
  • How does myelination affect action potential conduction?
    Myelination enables saltatory conduction, where impulses jump between nodes of Ranvier, increasing speed about 30 times.
  • What are the two types of synapses?
    Electrical synapses (gap junctions) and Chemical synapses (neurotransmitter release).
  • What are the six steps of chemical synaptic transmission?
    1. AP arrives, 2. Ca2+ channels open, 3. Neurotransmitter released, 4. Neurotransmitter binds receptor, 5. Ion channels open, 6. Neurotransmitter effect terminated.
  • What are EPSPs and IPSPs?
    Excitatory postsynaptic potentials depolarize membrane; inhibitory postsynaptic potentials hyperpolarize membrane.
  • What is neural integration?
    The process by which neurons process and integrate multiple synaptic inputs to produce a response.
  • What are the four types of neural circuits?
    Diverging, Converging, Reverberating, and Parallel after-discharge circuits.
  • What is synaptic potentiation?
    Repeated use of a synapse increases its efficiency, contributing to learning and memory.