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Recording-2025-03-04T12:58:56.844Z

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Recording-2025-03-04T12:58:56.844Z

Overview of Upcoming Quiz

  • Bonus quiz scheduled from Thursday to Saturday of this week.

  • No quiz will be held next week due to spring break.

Neurons and Glial Cells

  • Finish the basic information about neurons in the upcoming lecture.

  • Discuss types of neurons and glial cells.

    • Glial Cells: Supporting cells in the nervous system; crucial for the function of neurons.

Types of Neurons

  • Different kinds of neurons to be covered.

  • Neurons are responsible for generating electrical signals.

Electrical Signal Generation

  • Overview of the generation of electrical signals in neurons.

  • Dendrites and soma are initial parts of neurons involved in signal integration.

  • Axon initial segment: Site where signals are integrated based on inputs from multiple synapses.

Integration of Signals

  • Neurons can receive hundreds of synaptic inputs (depolarizing/hyperpolarizing).

  • The dominant signal will determine if an action potential is generated.

  • Integration of inputs is comparable to binary signaling (zeros and ones).

Voltage-Gated Channels

  • Channels open in response to membrane potential changes.

  • Threshold potential must be reached for channels to open.

Axon Structure and Functions

  • Axon Collateral: Branch of the axon that can form synapses.

  • Telodendria: Branches at the end of axons leading to synaptic knobs.

    • Release of neurotransmitters occurs here upon action potential arrival.

Synaptic Transmission

  • Neurotransmitter released in response to action potentials at synaptic knobs.

Neurons vs. Glial Cells

  • Neurons: Send electrical signals.

  • Glial Cells: Provide support, not directly involved in signaling.

Types of Glial Cells (CNS)

  1. Microglia:

    • Function as immune cells in the brain.

    • Monitor brain tissue for infections and inflammation.

    • Act as phagocytes to ingest damaged cells.

  2. Astrocytes:

    • Support neurons and form a structural framework within the brain.

    • Regulate ion concentrations in the extracellular fluid.

    • Remove excess neurotransmitters.

  3. Oligodendrocytes:

    • Myelinate axons in the central nervous system.

    • Their processes wrap around multiple axons in CNS.

Peripheral Nervous System (PNS) Glial Cells

  • Schwann Cells:

    • Form myelin sheath around a single axon.

    • Support repair and regeneration of peripheral nerves following damage.

  • Satellite Cells:

    • Surround neuron cell bodies in ganglia; regulate neurotransmitter levels.

Communication and Neurotransmitters

  • Discussion on how neurotransmitters become 'used'.

  • Release and recycling of neurotransmitters occur at synapses.

Axon Initial Segment Function

  • Acts as integration point for incoming signals; determines if action potential is triggered.

Action Potential and Signal Propagation

  • Action potential can propagate along the axon once initiated.

  • Na+ influx leads to depolarization; K+ efflux results in repolarization.

Length Constant and Signal Degradation

  • Signals lose strength over distance; requiring boosters to maintain intensity.

  • Length constant: Measure of how far electrical signals can travel without degrading.

Key Concept Review

  • Importance of maintaining resting membrane potential and ion gradients in neurons.

  • Memory retention of these concepts is crucial before moving forward into deeper topics, such as neuroplasticity and the mechanics of synapses.