The Nervous System

ScienceMs. Curd’s Class

The Five Senses

1. Sight2.Hearing3.Touch4.Smell5.Taste

SIGHT

light enters through the lens; pupil changes size with the amount

of light (smaller – less light); retina – back of the eye, contains rods (brightness)and cones (color)

SIGHT:Draw how light travels through the eye and detects color

HEARING

Sound waves are produced by vibrations;

sound waves enter the ear and travel through the auditory canal

stops at the eardrum; eardrum vibrates when sounds waves

strike it; transmits vibrations to a tiny bone called

the stirrup which causes fluid to move in ear;

movement of fluid sends signal to brain which interprets as sound.

The Ear

SIGHT:Draw how light travels through the eye and detects color

HEARING:How does sound travel through the ear?

TOUCH

sensory receptors in skin nerves in the outer layer of

skin sense textures nerves deeper in the skin

sense pressure

SIGHT:Draw how light travels through the eye and detects color

HEARING:How does sound travel through the ear?

TOUCH:Draw a picture of how your skin feels touch

SMELL

Smelling receptors sense chemicals in the air

in the back of the nose is a patch of tissue that grows hair-like fibers covered in mucus

Scent molecules enter the nose, stick to the mucus and bind to receptors in hair-like fibers

receptors send impulse to brain

SIGHT:Draw how light travels through the eye and detects color

HEARING:How does sound travel through the ear?

TOUCH:Draw a picture of how your skin feels touch

SMELL:Show how the nose registers a smell

TASTE

taste buds-small sensory receptors all over tongue, throat, and mouth

each taste bud has about 100 sensory cells that detect chemicals in foods

identify foods as sweet, sour, bitter, or salty.

SIGHT:Draw how light travels through the eye and detects color

HEARING:How does sound travel through the ear?

TOUCH:Draw a picture of how your skin feels touch

SMELL:Show how the nose registers a smell

TASTE:How does the tongue identify a taste?

Which sense is the most important?

CENTRAL NERVOUS SYSTEM

Brain and Spinal CordBrain protected by skull; spinal cord

protected by spineCommunicates with the rest of the

nervous system through electrical signals sent to and from neurons. (90 meters/sec)

BRAIN

Adult brain contains 100 billion nerve cells called neurons

Directly controls voluntary behavior like walking and thinking

Also controls most involuntary responses like heartbeat, blood pressure, fluid balance, posture

Different areas in the brain have specific functions; Example: Cerebellum helps control fine tune movement and balance, Medulla Oblongata regulates heartbeat and breathing and the Cerebrum is what you use when you think

Brain stem (lower part of brain) controls breathing and vomiting

SPINAL CORD

44 centimeters (that’s 17.2 inches!) long and weighs 35-40 grams (that’s just under a 10th of a pound

Main pathway for information connecting brain and nerves throughout the body

Spine consists of small bones called vertebrae Spinal cord is a double layered tube with an

outer layer of nerve fibers wrapped in tissue, an inner layer of nerve cell bodies, and a central canal that runs the entire length of the cord.

31 pairs of nerves are connected to spinal cord, which send impulses to the cord. Those impulses are then sent to the brain

PERIPHERAL NERVOUS SYSTEM

Nerves found throughout the body; connects the Central Nervous System to the rest of the body

Sensory Nerves: receive info from environment

Motor nerves: send signals to muscles to move

2 parts:Autonomic Nervous System-

InvoluntarySomatic Nervous System-voluntary

AUTONOMIC NERVOUS SYSTEM

controls the movement of the heart, smooth muscles in the stomach, the intestines, and the glands

Functions: to conserve and store energy and respond quickly to changes

Cerebellum (rear of brain) coordinates balance and related muscle activity

Brain stem controls heartbeat, respiration, and smooth muscles in the blood vessels

Fight or flight response

SOMATIC NERVOUS SYSTEM

controls voluntary movement through skeletal muscles and external stimuliMonitors movement and functions that

can be controlled consciously Controls skeletal muscles in arms,

legs, and rest of bodyControls muscles for speech and

senses