Nervous System Flashcards
Two parts of the nervous system
CNS - Central Nervous System
PNS - Peripheral Nervous System
Neuron
A nerve cell
Types of Neurons
Sensory Neuron - to CNS
Motor Neuron - away to muscles and glands
Interneuron - within CNS
Dendrites
Receive information
Carry electrical impulse towards cell body
Axons
Carry electrical impulses AWAY from cell body
Cell body
Contains a nucleus
Forms dendrites and axons
Myelin sheath
Insulates electrical impulses
Schwann cells
Secretes myelin sheath
Neurotransmitter swellings
Produce neurotransmitter chemicals
Movement of an Impulse
Receives a stimulus of sufficient strength
Ions move in and out of dendrites and axons
Electrical impulse travels along a neuron
Threshold
Least possible stimulus needed to send an impulse
Features of a nerve impulse
All or nothing rule (threshold is reached or not)
Impulses travel at same speed
Delay between impulses (to allow message to pass between neurons)
Only travel from sensory to motor neurons
Synapse
A region where two neurons come in close contact
Synaptic cleft
Tiny gap between two neurons
Events at a Synapse
- Electrical impulse at synapse stimulates release of neurotransmitter chemicals
- Chemicals diffuse along synaptic cleft
- Chemicals Enter neuron and are broken down
- Electrical impulse is regenerated