11 nervous system-2010 update stacy

Vertebrate Nervous Systems
Two major subsystems:
central nervous system (CNS)
peripheral nervous system (PNS)

Central Nervous System
Two main components:
brain
spinal cord

Peripheral Nervous System
Contains two main nerve types:
somatic nerves
involved with voluntary movement
autonomic nerves
involved with involuntary movement
senses / movement sympathetic / parasympathetic systems

Cells of the Nervous System
Two major cell types:
neurons
conduct electrical signals
glial cells
structural & insulating support for neurons

nucleus cell body axon dendrites axon terminal glial cell node of Ranvier

Form insulating myelin sheaths around the axons of many neurons.

Multiple Sclerosis
Mylein sheaths gradually deteriote
This results in a disruption of
nerve impulses.
Symptoms:
-Loss of coordination
-muscle control
-vision
-numbness
*Autoimmune disease

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 have a lot of lipid molecules.
Lipid molecules are poor electrical conductors, therefore,
the myelin sheath provides electrical insulation
neurilemma - myelin sheaths wrapped around each other

Grey / White Matter
Why are brains said to be made of grey and white matter?
white matter – neurons with neurilemma.
Situated between the brainstem and cerebellum.
grey matter – neurons without neurilemma.
The grey matter includes regions of the brain involved in muscle control, sensory perceptions, such as seeing and hearing, memory, emotions and speech.

Grey / White Matter

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

Interneuron
also known as association neurons
receives incoming signals from sensory neurons
delivers outgoing signals to neurons responsible for responses

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

Knee reflex

Neuron Repair
Do neurons regenerate?
Yes. Peripheral system neurons will repair faster than central system neurons.

11 nervous system-2010 update stacy

by stacybatras

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