Nervous SystemUnit 2: Cells, Tissues & Organ Systems

OverviewThe human brain contains about 100 billion

nerve cells or neurons

Each neuron may communicate with thousands of other neurons

All animals except sponges have a nervous system

What distinguishes nervous systems of different animal groups is how neurons are organized into circuits.

The Nervous System

The central nervous system (CNS) consists of a brain and spinal cord

The peripheral nervous system (PNS) contains all the nerves to relay information from the environment to the brain. It also controls

involuntary body responses such as digestion and breathing.

Nerve Tissue

Nerve tissue is made up of cells called neurons.

100 billion in the human brain

Conduct electrical signals (nerve impulses) from one area to another.

Insulated by myelin

Information ProcessingNervous systems process information in three

stages: Sensory input Integration Motor output

Sensory ReceptorsSpecial cells or tissues that receive input from

the external environment and send signals along the peripheral nervous system to the central nervous system.

Eyes, ears, mouth, muscles and skin have sensory receptors

Information goes to different parts of the brain.

LE 48-3

Sensor

Sensory input

Motor output

Integration

EffectorPeripheral nervous

system (PNS)Central nervous

system (CNS)

Different parts of the brain receive information from various senses

Cerebellum

Brainstem

Cerebrum

ReflexesReflexes are actions that do

not need involvement of the brain. That is the brain is not involved in the decision to move.

Examples Knee jerk Moving hand away from a hot

stove

Diseases of the Nervous SystemMultiple sclerosis

Huntington’s

Concussion

Epilepsy

Stroke

Parkinson’s

Videos and Additional Information to Checkout for Homework!! http://www.youtube.com/watch?v=i-NgGKSNiN

w&feature=related

http://www.youtube.com/watch?v=xRkPNwqm0mM&feature=related (nervous system - 51 sec)

http://www.youtube.com/watch?v=QmNQdLkkJHM (on reflexes) (19 sec)

http://kidshealth.org/PageManager.jsp?lic=1&article_set=59295&cat_id=20607 (animation - ~ 3 min)

http://www.youtube.com/watch?v=fY7J7bccNoU (concussions – 20 sec)

http://www.youtube.com/watch?v=oY19-JI648Q (teenage with a concussion – 3 min)