Nervous System Chapter 20 Section 1

You will learn  To describe how the body’s senses help monitor the environment.  To explain how the sensory organs respond to stimuli  To describe how the nervous system works with other body systems.  To infer possible connections between taste buds and sensitivity to flavors.

Close Your Eyes  With your eyes closed smell the aroma I put in front of you.  Keep your eyes closed until I tell you to open them.  What did it smell like?  How did you know what the smell was?

Senses connect the human body to its environment!  To maintain homeostasis your body constantly monitors the environment.  Your sense organs (eyes, ears, skin, tongue, nose) are responsible for monitoring: Sight, smell, touch, hear, and taste

Senses  Each sense can detect a specific type of change in the environment.  Pain, Pressure, and Temperature are sensed through what sensory organ?

A Stimulus  The sound of the horn is known as a: Stimulus- A change in your environment that you react to, such as smell, taste, sound, feeling, or sight.

Sight  Light rays enter the eye through the pupil  They are bent by the cornea (also protects the eye)  The lens helps focus light.  The pupils change size. Large in dim light. Smaller in bright light.

Sight  At the back of the eye, the light strikes a layer called the retina.  There are two types of cells in the Retina:  Rods-detects brightness  Cones-Sensitive to color  These are called photoreceptors

Hearing  Your ears detect sound waves produced by vibrations  Sound waves are enter the auditory canal. The canal ends at the eardrum. The eardrum vibrates when sound waves hit it.  These vibration are sent through bones called the hammer, anvil, and stirrup to the inner ear.  Cells in the cochlea detect the vibrations and send a message to the brain  RECAP: Auditory Canal  ear drum  Hammer  Anvil  Stirrup  Cochlea

Hearing  Semi-Circular Canals: help keep the body’s balance!  External ear: what you see on the outside  Auditory nerve: carries sound vibrations to the brain

Hearing

Touch  You touch with tiny receptors in the skin.  Nerves at the top of the skin detect textures.  Nerves deeper in the skin detect pressure.  Other receptors sense hot and cold.

Smell  Detects Chemical Information  In the back of the nose, there is a patch of tissue where hairlike fibers covered in mucus,  Molecules enters your nose, stick to the mucus, and bind to the receptors in the hairlike fibers  The receptors sends an impulse to your brain, and you perceive the scent.

Taste  Chemical process  Your tongue is filled with sensory structures known as taste buds. They are also found in the throat and roof of your mouth.

Taste  Each taste bud contains 100 sensory cells.  They detect sweet, sour, bitter, and salty tastes.  Taste is also due to smell.

Central Nervous System  Consists of the Brain and Spinal Cord  Communicates with nervous system through electrical signals sent through nerve cells.  Travel 90 meters per second  This is like you running the length of an entire soccer field in a second!

Brain  Adult: Contains 100 billion nerve cells called neurons.  Controls both Voluntary and Involuntary behavior  Neurons communicate within the brain

Parts of the Brain  Cerebellum: controls balance and coordination  Cerebrum: controls memories, thoughts, and sensory organs  Medulla: controls involuntary movement Medulla

Medulla Oblongata: Part of the Brain the Controls Anger and Aggression o+clip&view=detail&mid=F1C6648DCA58ACC71079F1C6648DCA58ACC 71079&first=0&FORM=LKVR

Spinal Cord  Main pathway for information from the brain to other parts of the body  Protected by the vertebral column  31 pairs of nerves sends sensory impulses into the spinal cord and then sends them to the brain.

Peripheral Nerve System  Includes Sensory and Motor Nerves  Sensory nerves- receive information from the environment (hot or cold) and pass information to the Central Nervous System  Motor Nerves- sends signals from you brain to your muscles

The Autonomic Nervous System  Controls the movement of the heart, the smooth muscles in the stomach, the intestines, and the glands. (involuntary)  It conserves energy  Responds quickly to changes (Fight or Flight Response)

Voluntary Nervous System  Monitors movement and functions that can be controlled consciously.  Controls the skeletal system and muscles that are responsible for speech and the senses.

Quiz  Explain the process by which you hear sound? (Tell me the Steps)  What happens to the pupil in dim light?

Quiz  The top area of skin is responsible for sensing what?  What do you have on your tongue to help you taste?

Quiz  What two parts are included in the central nervous system?  What is the autonomic nervous system responsible for?

Medulla Cerebrum Cerebellum Involuntary Sensory: Receives information Temp, Color, Pressure, pain, sound Motor: Movement Nervous System Central Nervous System Peripheral Nervous System Brain Spinal Cord 2 types of nerves 2 types of responses Voluntary

Michael J. Fox  the-future/the-flux-capacitor/ the-future/the-flux-capacitor/