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CHAPTER 6
The Nervous System
Nervous System: complex network of nervous
tissue that carries electrical messages.
Parts: Brain, spinal cord, and nerves
Functions: control muscles and maintain balance
The nervous system
is made up of
nerves (bundle of
cells)
Neuron: Nerve Cell
3 Parts
• Cell body-contains nucleus and organelles
• Dendrites-receives impulses from other cells
• Axon-pass nerve impulses on to other Neurons
(nerve cells)
Types of Neurons (3)
1. Sensory: carry information from the inside and
outside of the body to the spinal cord then to
the brain
2. Motor: carry information from the brain to the
body to respond
3. Interneurons: carry information between
sensory and motor.
Synapse: gap between one Neuron and another
neuron
How does the signal get across the gap?
• A chemical
messenger called a
neurotransmitter is
release from the
axon end of one
neuron and goes to
the dendrites of the
next neuron
• Like a relay race
Two parts of the Nervous System
1.Central nervous system• Brian and spine
2.Peripheral nervous system
• All of the other nerves in the body
Central Nervous System (CNS)
Brain consists of
1. Cerebrum-largest, thinking, sensing,
speaking, muscles
2. Cerebellum-body position, coordination
and balance
3. Brain stem-involuntary (breathing,
heartbeat, digestion)
1.Frontal: reasoning
2.Temporal: hearing
3.Parietal: touch
4.Occipital: sight
Peripheral Nervous System (PNS)
2-Divisions
1.Sensory division carries
sensory information and
internal organs to CNS
2.Motor division carries
information from the CNS to
muscles and organs
Brain Diseases
• Meningitis: swelling on the brain
• Epliepsy: seizures occur due to abnormal
electric activity in the brain
• Infection, injury tumor or unknown
• Alzheimer’s: memory loss, confusion, mood
swings
• Cause unknown
• Stroke: blood clot in brain
• Loss of normal mental functions