Page 1: Neuron Structure and Types

This page provides a detailed overview of the structure of a neuron and its components, as well as the types of neurons in the nervous system.

The neuron is composed of several key parts:

1. Cell Body (Soma): Contains the nucleus and is responsible for protein synthesis and metabolic activities.
2. Dendrites: Branched extensions that receive signals from other neurons.
3. Axon: A long fiber that conducts electrical impulses away from the cell body.
4. Myelin Sheath: An insulating layer that speeds up signal transmission along the axon.
5. Terminal Arborization: The branched end of the axon where neurotransmitters are released.

Vocabulary: Myéline (myelin) is a fatty substance that forms an insulating layer around nerve fibers, crucial for rapid signal transmission.

The nervous system is divided into two main parts:

• Central Nervous System (CNS): Includes the brain and spinal cord
• Peripheral Nervous System (PNS): Comprises nerves outside the CNS

There are three types of neurons based on their function:

1. Afferent neurons: Carry sensory information to the CNS
2. Efferent neurons: Transmit signals from the CNS to target organs
3. Interneurons: Connect different neurons within the CNS

Highlight: Neurons have a long lifespan and do not divide, making them particularly vulnerable to damage.

Example: The schéma du trajet du message nerveux (diagram of nerve signal pathway) shows how information flows from sensory receptors through afferent neurons to the CNS, then via efferent neurons to effector organs.