Lecture 1 Ch46: Organization of the Nervous System

These flashcards cover the fundamental concepts related to the organization of the nervous system, neuron structure, functions, and common pathologies.

Nervous System Functions

The four main functions are to control internal environment (homeostasis), program reflexes, control voluntary movement, and memory & learning.

CNS

Central Nervous System, consisting of approximately 100 billion interneurons.

PNS

Peripheral Nervous System, which includes sensory and motor neurons.

Neuron Structure

Neurons consist of dendrites, cell bodies, and axons.

Dendrites

Short, highly branched structures of a neuron that receive signals from sensory receptors.

Cell Body

Contains the nucleus and organelles, and forms synaptic connections.

Axons

Nerve fibers that convey signals to other neurons or effector organs.

Myelin Sheath

A protein sheath that insulates axons, increasing signal transmission speed.

Schwann Cells

Insulation cells that are the main glial cells of the motor and sensory neurons of the PNS.

Nodes of Ranvier

Gaps between Schwann cells allowing ionic diffusion to increase signal transmission speed.

Sensory Neurons

Afferent neurons that conduct nerve impulses inward toward the CNS.

Motor Neurons

Efferent neurons that conduct signals outward from the CNS to muscles.

Interneurons

Neurons that conduct signals within the CNS, facilitating communication between sensory and motor neurons.

Gray Matter

Regions of the CNS primarily composed of neuronal cell bodies.

White Matter

Regions of the CNS composed mainly of myelinated axons.

Multiple Sclerosis

An autoimmune disease that causes degeneration of the myelin sheath, leading to ion leakage.

Traumatic Brain Injury (TBI)

Injury to the brain resulting from impact, inertia, or shock wave trauma, with varying severity.