The Divisions and Main Structures of the Nervous System

Hwa Won and Samuel

Vocabulary• Brain: main part of central nervous system made of about

100 billion neurons• Nerve: Bundle of nerve fibers that carry sensory information• Spinal cord: Thick whitish nerve tissue enclosed by

vertebrae that links brain to most nerves• Cerebellum: largest part of brain that works over the senses

and causes skeletal muscles to move and complex mental processes

• Reflex: automatic response that comes out very quickly without control of the brain.

The Brain

• Contains about 100 billion neurons• The skull, 3 layers of connective tissue, and fluid

help protecting brain

The Cerebellum

• Keep balance of body• Organize body and thought in coordinate way

Brainstem

• Control body’s automatic actions (i.e. breathing/ heart beating)

The Central Nervous System

• It is like a control center of the body• Spinal cord links the central nervous system

with the peripheral nervous system• Brain is a part of the central nervous system• The nerves in your body work like a network

of interconnected wires

The Peripheral Nervous System

• Network of nerves other than central nervous system

• Connect nerves from central nervous system to whole body

• Impulse travel through spinal nerve in 2 directions

To/ from central nervous system

The Peripheral Nervous System (continued)

• Somatic nervous system control voluntary actions

(i.e. using fork/ tying shoelaces)• Automatic nervous system control

involuntary actions (i.e. regulating smooth muscles)

The Spinal Cord

• The vertebral column (backbone) surrounds it and therefore protects it

• It links the brain and the peripheral nervous system

• It is also protected by a watery fluid• It is about 45 cm long in men and about 43 cm

in women

Reflexes

• A rapid, involuntary response to a thread• Sometimes only the spinal cord is involved (no

brain involvement)• Used for protection, i.e. a burn after you touch a

hot surface • As your muscles contract, another impulse goes

from your hand to your brain, simultaneously • This impulse makes you feel pain

Safety and the Nervous System• Just like any other part of your body the nervous system can be

easily damaged• Concussion – an injury of the brain, when the cerebrum hits

the skull– Occurs if you hit your head very hard – Sometimes heals itself, but if not and uncured it can cause brain

damage– Wearing a helmet can prevent concussion in activities such as sports

• Spinal cord can be easily injured, too– Occurs when the vertebrae is injured– Very dangerous, it can paralyze body parts or even the whole body

Wear a Helmet!