Transcript Nervous System - Emery

Vertebrate Nervous Systems
Two major subsystems:
1. central nervous
system (CNS)
2.
peripheral nervous
system (PNS)
Central Nervous System
Two main components:
1. brain
2. spinal cord
Brain
Spinal Cord
Miami Project – Spinal Cord Injury Research
Peripheral Nervous System
Contains two main nerve types:
1. somatic nerves
 involved with voluntary movement
senses / movement
2. autonomic nerves
 involved with involuntary movement
sympathetic / parasympathetic systems
Cells of the Nervous System
Two major cell types:
1. neurons
 conduct electrical
signals
2. glial cells
 structural & insulating
support for neurons
Neuron Structure
dendrites
axon terminal
soma
node of Ranvier
axon
nucleus
glial cell
Glial Cells
Neuron Signalling
How do electrical signals pass through cells?
Membrane Potential
 glial cells provide insulation for electrical
impulses to pass through axon
 glial cell membrane has a lot of lipid molecules
 called a myelin sheath
 neurilemma - myelin sheaths wrapped around
each other
Glial Cell
Grey / White Matter
Why are brains said to be made of grey and white
matter?
 white matter – neurons with neurilemma
 grey matter – neruons without neurilemma
Grey / White Matter
Neuron Types
Sensory Neuron
 also known as afferent neurons
 carries signals from sensory receptors to the CNS for
processing
 photoreceptors (eyes)
 chemoreceptors (nose)
 thermoreceptors (skin)
 found in clusters of neurons—ganglia
Ganglia
Neuron Types
Interneuron
 also known as association neurons
 receives incoming signals from sensory neurons
 delivers outgoing signals to neurons responsible for
responses
Neuron Types
Motor Neuron
 also known as efferent neurons
 connected to tissues that respond according what
was detected
 muscle contraction
 gland secretion
Neuron Responses
Does all information detected by your senses go
through your brain?
 reflex arc – connects sensory and motor neurons
without going to the brain
Neuron Repair
Do neurons regenerate?
Yes. Peripheral system neurons will repair faster than
central system neurons.