Function of the Nervous System Receive Informationinside and

Function of the Nervous System Receive Informationinside and outside of the body Respond to Informationvoluntarily and involuntarily Maintain Homeostasisresponds to information it receives

A system that controls all of the activities of the body. The nervous system is made of: The brain The spinal cord The nerves The senses

The nervous system also allows you to react to a stimulus. A stimulus is a change in the environment. Example: putting your hand on a hot stove Or… tripping over a rock

Example: If a bug flies by your eye, you will blink A response is a reaction to a change in the environmnent (stimulus)

The Central Nervous System is made of the brain and the spinal cord. The Central Nervous System controls everything in the body.

The Peripheral Nervous System is made of the nerves and the sense organs. Nerves Sense organs

Basic Nerve Cell Structure Dendrite Axon Carries impulse towards the cell body Carries impulse away from the cell body Cell Body Axon Tips Nucleus Electric impulse changed into a chemical impulse

Three Main Types of Nerve Cells Cell Dendrite Body Axon Tips Sensory Neuron Interneuron Picks up Passes impulse from stimulus one nerve to another Motor Neuron Sends impulse to muscles

Message (signal) carried throughout the body by nerves.

How a Nerve Impulse Travels Sensory Neuron axon Skin cell body dendrite cell body axon impuls Interneuron e synapse axon tips dendrite e ls impu cell body Motor Neuron Skeletal Muscle

Transmission of Impulse (signal) The Synapsejunction (gap) between two nerves Axon Tip Dendrite Synapse (gap) Chemicals being released Electric impulse changes to a chemical impulse at the synapse

You have a nerve along your whole arm. The “funny bone” is the only place on the arm where the nerve is not protected. The “funny bone” is on the elbow.

An organ that controls your emotions, your thoughts, and every movement you make.

* The Central Nervous System controls all of the body’s activities. * The Central Nervous System is made of two main organs. 1. The brain 2. The spinal cord

* The spinal cord sends messages to the brain. * The spinal cord connects the brain to the rest of the nervous system.

* The brain controls everything in the body. * The brain is made of more than 10 billion nerves! * The brain is divided into three parts and is protected by the skull.

1. The Cerebrum 2. The Cerebellum 3. The Brain Stem

cerebrum brain stem cerebellum

* The Cerebrum is the largest part of the brain. 1. The cerebrum controls your thinking. 2. The cerebrum controls your memory. 3. The cerebrum controls your speaking. 4. The cerebrum controls your movement and identifies the information gathered by your sense organs.

* The cerebellum is below and to the back of the cerebrum. 1. The cerebellum controls you balance. 2. The cerebellum controls your posture.

* The Brain Stem connects the brain to the spinal cord. * The nerves in the brain stem control your heartbeat, breathing, and blood pressure.

* The vertebrae are the many bones that protect the nerves in the spinal cord.

*The spinal cord sends messages to the brain. *The spinal cord is the part of the nervous system that connects the brain to the rest of the nervous system.

Made of sensory and motor neurons (nerve cells)bundled together Impulses travel in two directions. • Impulses travel from the body to the spinal cord through the sensory neurons. • Impulses travel from the spinal cord to the body through the motor neurons.

Nervous System Injuries • Concussion Bruise-like injury of the brain caused by soft tissue of the brain colliding against the skull. Happens when you bump your head during a hard fall, accident, or playing a contact sport. • Spinal Cord Injury The spine can be crushed or cut. This type of injury often results in paralysis because nerve impulses can’t pass through the damaged section of the spinal cord.

* carries messages between the central nervous system and the rest of the body. * connects the Central Nervous System to the rest of the body.

* made of the nerves and the sense organs. Ear Skin Eye Nerves Tongue

Peripheral Nervous System Nerves connect CNS to the body Nerves are made of • Motor neurons- carry impulses from CNS to muscles and organs. • Sensory neurons - sensory receptors on organs and muscles carry impulses to CNS. Spinal Cord Brain Nerves

* controls the body’s activities that you don’t think about. * controls activities in your small intestine, your breathing, and your heartbeat. controls

* controls the body’s activities that you think about. * controls activities such as using a fork and tying your shoes, turning your head controls

* An automatic reaction that happens without thinking about it. * A reflex happens quickly in less than a second.

Reflex Action

The eyes, ears, nose, tongue, and skin are examples of sense organs. The sense organs gather information (light, sound, heat, and pressure) from the environment.

The environment is everything outside the body. The sense organs gather information from outside the body, then send the messages to central nervous system.

Vision is your ability to see. Vision involves the eye and the brain.

The eye is one of your sense organs. The eye is made of the iris and the pupil. The eye gathers pictures and sends them to the brain.

The colored part of the eye is the iris. The muscles in the iris control the size of the opening (pupil) The pupil becomes larger and smaller as the iris controls the light coming Iris Pupil into the eye.

The cornea is a clear tissue that allows light to enter the eye. The clear flexible structure that focuses the light as it enters is the lens. The retina is a layer of special nerve cells that respond to light coming into the eye. Optic nerve sends nerve impulses to the brain

Iris Retina Cornea Pupil Lens Optic Nerve

How You See an Image • Light passes into the eye through the cornea then through the pupil. • Next the light passes through lens and bends. • As the light bends the image flips over. • When light hits the retina the nerve cells (rods and cones) sense the upside down image. • The optic nerve sends the impulses to the brain. The brain reverses the image and combines the images from each eye.

Rod and cone nerve cells

Rods and Cones Rods help you see black, white and gray shades Cones help you se colors

Sound is produced by vibrations, the air around the sound vibrates. Hearing starts when some of the sound vibrations go into the ear.

There are eight main parts of the ear. 1. Outer ear 5. Anvil 2. Ear canal 6. Stirrup 3. Ear drum 7. Cochlea 4. Hammer 8. Auditory nerve

The outer ear is the part of the ear that you can see. It gathers sound around you. The ear canal is the tube that is the pathway for the sound The ear drum is in the middle ear. It vibrates when sound waves hit it.

The three smallest bones in the body, the hammer, the anvil, and the stirrup, are in the middle ear. The hammer gets the vibrations from the eardrum, then sends them to the anvil. The anvil passes the vibrations to the stirrup. The stirrup passes the vibrations to the cochlea.

The inner ear is made of the cochlea filled with liquid. When the liquid vibrates it activates sensory neurons The auditory nerve carries the impulses to the brain and the brain tells us what we heard.

Outer Ear Middle Ear Inner ear Semicircular canals Ear (pinna) Auditory Nerve Ear Canal Cochlea Stirrup Hammer Eardrum Anvil

The ear works with the brain to control your balance. The semicircular canals are responsible for your balance. • The liquid in your canals moves when you move. • The liquid makes the hair-like structures in the canals move. • This motion sets off nerve impulses that are sent to the to brain to tell it how we are moving.

The sense of touch is located in the skin. The nerves in the skin allow us to feel texture, pressure, temperature (heat, cold) and pain. Texture is how something feels.

Touch Type of Nerve Receptor Location Light touch Upper dermis pressure Lower dermis pain Lower dermis temperature Lower dermis Function Sense when you brush up against something and senses textures Senses anything that presses against skin Alerts your body to possible danger Senses heat

The nose controls your sense of smell. The nose is able to smell 80 different kinds of smells.

Your sense of taste comes from the taste buds in the tongue. Taste buds are nerve receptors on the tongue that allow us to taste. The five kinds of taste buds are sweet, sour, bitter, salty, and umami (meat-like taste).

The senses of taste and smell depend on chemicals in your food and in the air to create flavors.