Coordinates all the body’s activity The Nervous System Coordinates all the body’s activity

The Nervous System 1. Two main divisions a. Central Nervous System (CNS) – consists of brain and spinal cord b. Peripheral Nervous System (PNS) – includes nerves extending from brain and spinal cord c. The CNS receives messages from the PNS, interprets them, and then sends out a response.

Neurons 2. Neurons - nerve cells that transmit messages to and from the spinal cord and brain a. Sensory Neurons – carry messages FROM body TO CNS ex. Playing games in computer lab. When light switches to green, a sensory neuron transmits a message from your eye to your brain

Neurons b. Motor Neurons – carry message TO body FROM CNS ex. Your brain sends a signal through a motor neuron to tell your finger to click the mouse. c. Interneurons – connect neurons

3. Structure and Functions of Neurons 1. Dendrites – receive information and transmit impulses toward cell body 2. Cell Body – large area which contains cell nucleus or power plant 3. Nucleus – command center of the neuron

4. Axon – transmit impulses away from cell body and toward axon terminal 5. Axon Terminals – branched structures at the ends of neurons. 6. Myelin Sheath – insulating coat which covers the axon. This helps messages relay faster.

Neuron

Motor Unit

The Central Nervous System 1. The brain a. Helps you think, remember, reason, feel emotion, and coordinate muscle movement b. Divided into three main parts: cerebrum, cerebellum, brain stem

The Brain

The Central Nervous System 2. The Cerebrum a. largest, most complex part of brain b. right and left sides communicate with each other to coordinate movement. Right controls left side and vice versa. c. left hemisphere is for language, reasoning, and critical, concrete thinking d. right hemisphere is for abstract thinking

The Central Nervous System 3. Four lobes (parts) of the cerebrum a. Frontal Lobe –use of language b. Parietal Lobe – sensory information, including feelings of heat, cold, pain, touch c. Occipital Lobe – Controls sense of sight d. Temporal – sense of hearing and smell

Lobes of the Brain

The Central Nervous System 4. The Cerebellum a. second largest part of brain b. maintains body’s posture and balance c. coordinates complex muscle movements like serving a volleyball or playing violin

The Central Nervous System 5. The Brain Stem a. 3 inch long stalk of nerve cells that connect the spinal cord to the rest of the brain

The Central Nervous System b. five parts 1. Medulla Oblongata – regulates heartbeat, breathing rate 2. Pons – controls muscles of eye and face. 3. Midbrain – controls pupil size 4. Thalamus – relays incoming information from the eyes, ears, and pressure receptors in skin 5. Hypothalamus – regulates body temp, appetite, sleep

Brain Stem

The Peripheral System 1. Broken into two parts a. Autonomic Nervous System – controls involuntary functions such as digestion and heart rate - you cannot control this; it is automatic! (autonomic) b. Somatic Nervous System – voluntary responses that are under your control - feeling and itch on your skin and scratching it

The Peripheral System 2. Autonomic Nervous System a. Broken down into two smaller networks b. Sympathetic nervous system – kicks in when you are startled. Messages are sent that increase your heart rate. Also, blood vessels dilate to allow for greater blood flow. - “Fight or flight response” - Example… you are riding in a car and a deer jumps out in front of you. Think about how you feel. Your body prepares you to make a sudden reaction.

The Peripheral System c. Parasympathetic nervous system – opposite of sympathetic nervous system - slows heartbeat, relaxes blood vessels, lowers blood pressure

Problems of the Nervous System 1. Headaches – caused by muscle tension, eyestrain, sinus infection, dehydration, or food allergies 2. Head injuries a. concussion – a temporary loss of consciousness http://www.youtube.com/watch?v=Tyv4du7BTOc

Problems of the Nervous System 3. Spinal Injuries a. swelling of spinal cord tissue can result in temporary loss of nerve function b. if spinal cord is severed, you may become paralyzed. http://www.youtube.com/watch?v=DCyG7xH9C98

Problems of the Nervous System 4. Meningitis – inflammation of the spinal and cranial meninges caused by a virus or bacteria a. symptoms include fever, headache, light and sound sensitivity, and neck stiffness. b. can result in death

How to care for/prevent these problems: 1. Eat a well-balanced diet, exercise regularly, get lots of sleep! 2. Wear protective devices – helmet, seat belt 3. Stay away from drugs and alcohol!!!

Nervous System PNS CNS Somatic Spinal Cord Autonomic Brain Cerebrum Brain Stem Cerebellum Sympathetic Parasympathetic Pons/Medulla/Hypothalamus/Midbrain/Thalamus