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Nervous System Basics and Neuron Function

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  • What is the central nervous system (CNS)?

    The CNS consists of the brain and spinal cord.

  • What is the peripheral nervous system (PNS)?

    The PNS includes all nerves outside the CNS.

  • What is the function of the PNS?

    The PNS carries information to and from the CNS.

  • Which division carries information TO the CNS?

    The afferent (sensory) division carries information to the CNS.

  • Which division carries information FROM the CNS?

    The efferent (motor) division carries information from the CNS.

  • What are neurons?

    Neurons are cells that conduct electrical signals.

  • What are neuroglial cells?

    Neuroglia support, protect, and nourish neurons.

  • What do ependymal cells do?

    Ependymal cells produce and circulate cerebrospinal fluid (CSF).

  • What is the function of astrocytes?

    Astrocytes form the blood-brain barrier, repair tissue, and provide support.

  • Which cells produce myelin in the CNS?

    Oligodendrocytes produce myelin in the CNS.

  • Which neuroglia act as immune cells?

    Microglia perform phagocytosis and immune defense in the CNS.

  • What do satellite cells do?

    Satellite cells surround neuron cell bodies in the PNS.

  • Which cells produce myelin in the PNS?

    Schwann cells produce myelin in the PNS.

  • How do Schwann cells differ from oligodendrocytes?

    One Schwann cell myelinates one axon segment, while oligodendrocytes myelinate multiple axons.

  • What part of a neuron receives input?

    Dendrites receive signals from other cells.

  • What contains the nucleus in a neuron?

    The cell body (soma) contains the nucleus.

  • What part of a neuron carries signals away?

    The axon carries electrical signals away from the cell body.

  • Where are neurotransmitters released?

    Axon terminals release neurotransmitters into the synapse.

  • What is the most common neuron type structurally?

    Multipolar neurons are the most common type.

  • Which neurons are found in special senses?

    Bipolar neurons are found in special sensory organs.

  • Which neurons are sensory?

    Unipolar neurons function as sensory neurons.

  • Which neurons carry information TO the CNS?

    Sensory (afferent) neurons carry information to the CNS.

  • Which neurons carry commands FROM the CNS?

    Motor (efferent) neurons carry commands from the CNS.

  • Which neurons connect neurons within the CNS?

    Interneurons connect neurons in the CNS and make up 99% of neurons.

  • What is a synapse?

    A synapse is the communication junction between two neurons.

  • What is the space between neurons called?

    The synaptic cleft is the gap between neurons at a synapse.

  • Which neuron sends the signal at a synapse?

    The presynaptic cell sends the signal.

  • Which neuron receives the signal at a synapse?

    The postsynaptic cell receives the signal.

  • What is resting membrane potential?

    Resting potential is the negative charge inside a neuron at rest.

  • What is a graded potential?

    A graded potential is a local, variable change in membrane potential.

  • What type of signal is an action potential?

    An action potential is an all-or-none electrical signal.

  • What happens during depolarization?

    Depolarization occurs when Na⁺ ions enter the neuron, making it more positive.

  • What happens during repolarization?

    Repolarization occurs when K⁺ ions exit the neuron, restoring negativity.

  • What is hyperpolarization?

    Hyperpolarization is when the membrane potential temporarily becomes more negative than resting.

  • What does all-or-none mean in action potentials?

    Once threshold is reached, a full action potential occurs; otherwise, none occurs.

  • When can no new action potential occur?

    During the absolute refractory period, no new action potential can be generated.

  • When is a stronger stimulus needed to trigger an action potential?

    During the relative refractory period, a stronger stimulus is required.

  • What type of conduction is slow?

    Continuous conduction is slow and occurs in unmyelinated axons.

  • What type of conduction is fastest?

    Saltatory conduction is fastest, jumping between nodes of Ranvier.

  • What is the function of myelin?

    Myelin speeds up electrical conduction along axons.

  • Who makes CNS myelin?

    Oligodendrocytes produce myelin in the CNS.

  • Who makes PNS myelin?

    Schwann cells produce myelin in the PNS.

  • What ion causes depolarization?

    Na⁺ (sodium) ions entering the cell cause depolarization.

  • What ion causes repolarization?

    K⁺ (potassium) ions exiting the cell cause repolarization.

  • What is the difference between neurons and neuroglia?

    Neurons send signals; neuroglia support and protect neurons.

  • Why is myelin important?

    Myelin increases the speed of electrical signal conduction.

  • What type of signal is an action potential?

    An action potential is an all-or-none electrical signal.

  • Which conduction is fastest?

    Saltatory conduction is the fastest conduction type.