1. The Nervous System

2. Central vs. Peripheral There are two main divisions with the nervous system: –Central Nervous System (CNS) –Peripheral Nervous System (PNS The CNS contains the brain and spinal cord The PNS connects the CNS to the sensory organs, other organs, muscles, blood, vessels, and glands

3. CNS The brain controls all of the body systems and the organ function in our body The brain communicates with the body through the spinal cord and nerves Once the nerves leave the spinal cord, they divide off into smaller and smaller branches in order to reach everything in the body The thickest nerve is over 2cm thick and the thinnest nerve is thinner than a strand of human hair

4. PNS This is composed of all of the nerves in the body Neurons link together in a series of complex pathways in order to send and receive messages throughout the entire body Nerve cells are limited in their ability to repair themselves and are not able to replace damaged cells

5. Pathways of the PNS There are two main pathways in the PNS: –Sensory (send messages to the CNS) –Motor (send messages to muscles and glands) There are two divisions with the PNS: –Somatic Nervous System (muscular and external sensory) –Autonomic Nervous System (controls internal organs)

6. Somatic Nervous System Responsible for voluntary movement and responding to stimuli (sensory processing) Controls all 5 senses There are two parts within this system Sensory neurons carry impulses from sense organs to the CNS Motor neurons carry impulses from the CNS to the muscles

7. Autonomic Nervous System Controls the internal organs (heart, smooth muscle, and glands) It is involuntary Divided into two part: –Sympathetic Accelerates heart rate, constricts blood vessels, raises blood pressure –Parasympathetic Slows heart rate, increases intestinal and gland activity, relaxes sphincter muscles

8. Putting It All Together The Nervous System Central Nervous System (brain and spinal cord) Peripheral Nervous System (nerves) Somatic Nervous System (voluntary) Afferent Nervous System (from PNS to CNS - sensory) Efferent Nervous System (from CNS to PNS – motor) Autonomic Nervous System (involuntary) Sympathetic Nervous System (Fight or Flight Response) Parasympathetic Nervous System (Sleeping)