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Structure and Function of Neurons
Jul 8, 2024
Structure and Function of Neurons
Introduction
Video Speaker:
Ninja Nerds
Topic:
Structure and Function of Neurons
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Structural Components of a Neuron
Dendrites
Extensions from the neuron, called receptive zones.
Cell Body (Soma)
Circular structure housing the nucleus and various organelles.
Axon
Long, elongated portion of the neuron.
Special part:
Axon Hillock
(high concentration of voltage-gated sodium channels).
Axon Terminal (Synaptic Terminal/Bulb)
Bulbous structure at the end of the axon.
Functions of Neuronal Components
Dendrites
Receptive Zone:
Receives signals from other neurons.
Ligand-Gated Ion Channels:
Formation of EPSPs (Excitatory Post-Synaptic Potentials) and IPSPs (Inhibitory Post-Synaptic Potentials).
Graded Potentials:
Small changes in membrane voltage that help generate action potentials.
G-Protein Coupled Receptors:
Activate second messengers and protein kinases for various cellular responses.
Cell Body (Soma)
Graded Potentials:
Shared function with dendrites.
Protein Synthesis: Major Function
Rough Endoplasmic Reticulum (Nissl Bodies)
: Translation of mRNA to proteins.
Golgi Apparatus:
Protein modification and packaging.
Axon
Action Potentials:
Electrical currents that travel from the cell body to the axon terminal.
Phases of Action Potentials:
Depolarization followed by repolarization.
Motor Proteins:
Kinesin (anterograde transport) and dynein (retrograde transport).
Axonal Transport:
Movement of vesicles, organelles, and other cellular components.
Microtubules and Motor Proteins
Kinesin:
Transports vesicles containing neurotransmitters, mitochondria, etc., from cell body to axon terminal.
Dynein:
Transports degraded or used materials back up to the cell body.
Clinical Relevance:
Pathogens like polio and herpes viruses utilize these pathways.
Axon Terminal
Secretory Region:
Release and reuptake of neurotransmitters.
Voltage-Gated Calcium Channels:
Allow calcium influx, triggering neurotransmitter release.
SNARE Proteins:
Facilitate vesicle fusion with the axonal membrane for neurotransmitter release.
Neurotransmitter Termination:
Done by degradation or reuptake.
Reuptake Mechanism:
Important for recycling neurotransmitters and impacted by SSRIs.
Neuronal Classifications
Structural Classification
Multipolar Neurons
Multiple dendritic extensions, found in areas requiring multiple inputs (e.g., motor cortex, cerebellum).
Bipolar Neurons
One dendritic extension and one axon, found in special sensory organs (e.g., retina, olfactory epithelium).
Pseudo-Unipolar Neurons:
Peripheral and central processes with the cell body in between.
Found in dorsal root ganglia and cranial nerves.
Functional Classification
Sensory Neurons (Afferent)
General Visceral Afferent (GVA): From visceral organs.
General Somatic Afferent (GSA): From skin, muscles, joints.
Special Sensory Afferent (SSA): From vision and hearing organs.
Special Visceral Afferent (SVA): From taste and smell sensors.
Motor Neurons (Efferent)
General Visceral Efferent (GVE): To visceral organs.
General Somatic Efferent (GSE): To skeletal muscles.
Special Visceral Efferent (SVE): To head and neck muscles derived from pharyngeal arches.
Interneurons
Connect sensory and motor pathways; predominantly found in the brain and spinal cord.
Conclusion
Summary:
Covered the structure and function of different neuron parts.
Further Research:
Graded potentials, action potentials, protein synthesis in neurons.
Importance:
Understanding neurons' structure/function is crucial for grasping neurological concepts.
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