Physio Chapter 1 (The Minds Machine)

Neurons “nerve cells”

Basic units of the nervous system

Typical Neuron has FOUR main parts and what do they do?

Dendrites: receive information

Cell body (soma): integrates information

Axon: carries impulses from neuron

Axon terminal: transmit neuron signals to other cells

Neurons almost always contain what? (hint: 4 things)

input zone, integration zone, conduction sone, and output zone

Synapse

Cellular location where info is transmitted from a neuron to another cell

Glial Cells aka glia

nonneuronal brain cells. Provide structural, nutritional, and other support to the brain

Neuron Doctrine

1. neurons and other cells of the brain are structurally, metabolically, and functionally independent.

2. info is transmitted from neuron to neuron across small gaps called “synapses”

Input Zone

Dendrites (receive info from other neurons via synapses)

Integration Zone

Cell Body [Soma, plural Somata] (receives additional synaptic input and integrates the info that has been received)

Conduction Zone

Axon [Nerve Fiber] (a single extension, carries the neuron’s own electrical signal away from the cell body)

When an axon splits into multiple branches

axon collaterals

Output Zone

Axon Terminals [Synaptic Boutons] (specialized swellings at the ends of the axon that transmit the neuron’s signal across synapses to other cells)

Three Principal Types of Neurons

1. Multipolar

2. Bipolar

3. Unipolar

Multipolar

many dendrites (branches) and a single axon, most common

Bipolar Neurons

single dendrite at one end of the cell and single axon at the other end (especially common in sensory systems like vision)

Unipolar Neurons (Monopolar)

a single extension (or process) usually thought of as an axon that branches in two directions after leaving the cell body. One end is the input zone, the other an output zone with terminals. (transmit touch info from body into the spinal cord)

Synaptic Cleft

space between presynaptic and postsynaptic neurons

Synapses THREE principal components

1. presynaptic membrane (axon terminal)

2. synaptic cleft

3. postsynaptic membrane (dendrite or cell body)