The Nervous System Science Ms. Curd’s Class

The Five Senses 1. Sight 2. Hearing 3. Touch 4. Smell 5. 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 Cord Brain protected by skull; spinal cord protected by spine Communicates 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 grams (that’s just under a 10 th 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-Involuntary Somatic 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 stimuli Monitors movement and functions that can be controlled consciously Controls skeletal muscles in arms, legs, and rest of body Controls muscles for speech and senses