The Nervous System Main Function: receive stimuli from inside and outside the body, to interpret the stimuli and initiate responses for survival a thing or event that evokes a specific functional reaction in an organ or tissue.

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

What does a real neuron look like?

Neuron

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 Synapse

Nerves of the Body

Motor Unit Motor Unit – A neuron and all the muscles it gives power to.

The Central Nervous System 1. The brain organ which has 3 distinct parts that all serve to control and coordinate the activities of the body: Cerebrum Cerebellum Brainstem

The Brain

The Central Nervous System 2. The Cerebrum a. largest, most complex part of brain b. controls thoughts, voluntary actions and sensations related to the 5 senses c. right and left sides communicate with each other to coordinate movement. Right controls left side and vice versa

Are you left or right brained?!

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. small lobe located at the back of the 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 is located at the base of the brain, connect the spinal cord to the rest of the brain controls vital and involuntary processes (breathing, heartbeat, digestion)

The Central Nervous System b. five parts 1. Medulla Oblongata – regulates heartbeat, breathing rate 2. Pons – controls muscles of eyes 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 Spinal Cord A bundle of nerves that begins at the brainstem and continues down the center of the back through the vertebrae. Connects to peripheral nerves

Peripheral Nerves Network of nerves that branch out from the spinal cord and connect to the rest of the body Transmits signals to and from the brain through the spinal cord

So, how exactly does all this work? https://www.youtube.com/watch?v=jdJpLvSTZMU

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

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.

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!!!