1. Nervous System Unit 2: Cells, Tissues & Organ Systems

2. Overview  The 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.

3. 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.

4. 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

5. Information Processing  Nervous systems process information in three stages:  Sensory input  Integration  Motor output

6. Sensory Receptors  Special 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.

7. LE 48-3 Sensor Sensory input Motor output Integration Effector Peripheral nervous system (PNS) Central nervous system (CNS)

8. Different parts of the brain receive information from various senses Cerebellum Brainstem Cerebrum

9. Reflexes  Reflexes 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

10. Diseases of the Nervous System  Multiple sclerosis  Huntington’s  Concussion  Epilepsy  Stroke  Parkinson’s

11. Videos and Additional Information to Checkout for Homework!!  http://www.youtube.com/watch?v=i- NgGKSNiNw&feature=related http://www.youtube.com/watch?v=i- NgGKSNiNw&feature=related  http://www.youtube.com/watch?v=xRkPNwqm0mM&fea ture=related (nervous system - 51 sec) http://www.youtube.com/watch?v=xRkPNwqm0mM&fea ture=related  http://www.youtube.com/watch?v=QmNQdLkkJHM (on reflexes) (19 sec) http://www.youtube.com/watch?v=QmNQdLkkJHM  http://kidshealth.org/PageManager.jsp?lic=1&article_set= 59295&cat_id=20607 (animation - ~ 3 min) http://kidshealth.org/PageManager.jsp?lic=1&article_set= 59295&cat_id=20607  http://www.youtube.com/watch?v=fY7J7bccNoU (concussions – 20 sec) http://www.youtube.com/watch?v=fY7J7bccNoU  http://www.youtube.com/watch?v=oY19-JI648Q (teenage with a concussion – 3 min) http://www.youtube.com/watch?v=oY19-JI648Q