The Nervous System
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Transcript The Nervous System
SNC 2D
The organ system that is made up of
the brain, spinal cord, and the
peripheral nerves
System that senses the environment
and coordinates appropriate responses
Consists of the brain and the spinal cord
Shielded by bones
Skull protects the brain
Spine protects the spinal cord
Cerebrospinal fluid surrounds the brain and spinal
cord – cushions against injury and transports
chemicals and waste
Consists of the nerves that connect the body to the
central nervous system
Relays information about the internal and external
environments of the brain
Subdivided into
A) nerves that control voluntary muscles
B) nerves that carry information from sensory organs
C) nerves that regulate involuntary functions
Specialized cells that make up nerve tissue are called
neurons
Found in brain, spinal cord and nerves
Approximately 100 billion neurons in human brain
Neurons conduct electrical signals (nerve impulses)
from one area of body to another
Nerve cell sends a signal through axon
Attaches to dendrites of another cell
Continues until reaches muscle cells
Signal goes in only one direction
Fatty material that surrounds the axon
Acts like an electrical wire preventing electrical
impulses from passing to the wrong neuron
Bundles of neurons surrounded
by connective tissue
Allow two-way flow of information
even though each neuron transmits
information only in one direction
Special cells or tissues that receive input from our
external environment and send signals along our
peripheral nerves to our central nervous system
Ears, mouth, nose, muscles, and skin
Other receptors are sensitive to
pressure, temperature, and pain and
make us aware of our balance,
position and motion
Increase/decrease breathing rate
Heart beat faster/slower
Eat/drink/stop
Perception
Spinal Cord – acts as a short cut for reflexes
Reflexes do not use brain, occur without conscious
thought (move hand away from hot surface)
Peripheral nervous system can undergo cell division to
repair severed nerves (few mm distance)
Central nervous system do not regenerate easily
Multiple Sclerosis – destroys myelin sheaths so that
signals are mixed up
Fall or blow – can result in paralysis, concussions
Viruses and bacteria can cause permanent damage in
brain
nervous system
pork tapeworm