3. Neurons and Reflex Arcs

Neuron

the basic structural and functional unit of the nervous system

Dendrites

Part of the neuron which receives information from other nerve cells and sends it towards the cell body

axon

part of the neuron which sends nerve impulses away from cell body

Myelin sheath

layer of tissues that insulate neurons from each other and increases the speed of the nerve impulse

Synapse

a small gap that acts as a junction between two adjacent nerve cells

Axon terminals

The rounded ends of axons where neurotransmitters are made and stored.

Node of Ranvier

Areas on the axon which are NOT covered in myelin

Schwann cells

Cells that wrap around the axon to form the myelin sheath

Nucleus

Control centre of the cell

Electrochemical

Method of communication with the nervous system

Neurotransmitter

Chemical that crosses a synapse to transfer the nerve impulse across a synapse

receptors

Parts of the sensory neurons that detect a change in the internal environment

Sensory neuron

carry messages from cells in sense organs to the brain and spinal cord (CNS)

Connector neuron

Carry messages from sensory neurons to the motor neurons in a reflex arc

Motor neuron

carry messages from connector neurons to effectors to carry out a response

Effector

Structures that remove body parts from danger in a reflex arc

Reflex arc

A neural pathway that controls an action that typically prevents injury

Stimulus

Change in the internal environment

Response

A reaction that alters the stimulus