The Nervous System Introduction Master control and communicating system

Learning Objectives To determine the general functions and division/organization of the nervous system.

I. What is the nervous system? The master controlling and communicating system of the body.

II. Functions of the Nervous System 1. Sensory Input- gathering information (senses). To monitor changes occurring inside and outside the body. Changes=stimuli 2. Integration= Brain To process and interpret sensory input and decide if action is needed.

3. Motor Output A response to integrated stimuli The response activates muscles or glands= effector organs.

Examples: Smell a cookie  Sensory Input  Brain (process)  Motor Output  Hand to grab and eat cookie

Sensory Input, Integration or Motor Output? You see a sabertooth tiger running at you. Your eyes send a nerve impulse to your brain. Your brain processes that you are about to get attacked and eaten A nerve impulse is sent from you brain to the muscles in your legs allowing you to run away from the sabertooth tiger Sensory Input Integration Motor Output

III. How is the Nervous System Organized? A. Central Nervous System (CNS) Brain and Spinal Cord Integrative and control centers B. Peripheral Nervous System (PNS) Nerves (spinal nerves, cranial nerves) Communication lines between CNS and rest of body. Two Divisions of PNS: 1. Sensory (afferent) Division: Sensory receptors  CNS 2. Motor (efferent) Division: CNS  effectors (muscles and glands)

Motor Division a. Somatic Nervous System (voluntary)- control skeletal muscles b. Autonomic Nervous System (ANS) (involuntary)- regulates smooth muscles, cardiac, glands

Divisions of ANS: 1. Parasympathetic NS- “resting and digesting system” Most active in non-stressful situations Keeps energy use low and maintains vital housekeeping activities running. 2. Sympathetic NS- “fight or flight” division Exercise, excitement, emergency, and embarrassment division. Prepares the body for action.

1. Central Nervous System 2. Peripheral Nervous System A. Sensory Division B. Motor Division 1. Somatic NS 2. Autonomic NS A. Parasympathetic NS B. Sympathetic NS

Example 1: CNS: brain & spinal cord (processes and interprets) Step on nail Muscles of leg (effector)= somatic Sense organ (pain receptor in foot) PNS: nerves (motor) Move foot away from nail PNS: nerves (sensory)

Example 1: Sense organ (pain receptor in foot) Step on nail Sensory input PNS: nerves (sensory) CNS: brain & spinal cord (processes and interprets) Motor output PNS: nerves (motor) Muscles of leg (effector)= somatic Move foot away from nail

Example 2: CNS: brain & spinal cord (processes and interprets) Low oxygen Sense organ/receptor PNS: nerves (motor) PNS: nerves (sensory) Lungs and Diaphragm to breathe= autonomic (parasympathetic ns)

Example 2: Sense organ/receptor Low oxygen PNS: nerves (sensory) Sensory input PNS: nerves (sensory) CNS: brain & spinal cord (processes and interprets) Motor output PNS: nerves (motor) Lungs and Diaphragm to breathe= autonomic (parasympathetic ns)