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.