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

SensesEach 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.

SightAt 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

HearingYour ears detect sound waves produced by

vibrationsSound 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 Canalear drumHammerAnvilStirrupCochlea

HearingSemi-Circular Canals: help keep the

body’s balance!External ear: what you see on the

outsideAuditory nerve: carries sound

vibrations to the brain

Hearing

TouchYou 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.

SmellDetects 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 processYour tongue is filled with sensory structures known as taste buds. They are also found in the throat and roof of your mouth.

TasteEach taste bud

contains 100 sensory cells.

They detect sweet, sour, bitter, and salty tastes.

Taste is also due to smell.

Central Nervous SystemConsists of the Brain and Spinal CordCommunicates 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!

BrainAdult: Contains

100 billion nerve cells called neurons.

Controls both Voluntary and Involuntary behavior

Neurons communicate within the brain

Parts of the BrainCerebellum:

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 Aggressionhttp://www.bing.com/videos/search?q=Waterboy+medulla+oblongota+video+clip&view=detail&mid=F1C6648DCA58ACC71079F1C6648DCA58ACC71079&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 NervesSensory 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 SystemControls the movement of the heart, the smooth muscles in the stomach, the intestines, and the glands. (involuntary)It conserves energyResponds quickly to changes

(Fight or Flight Response)

Voluntary Nervous SystemMonitors 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?

QuizWhat two parts are included in the central nervous system?

What is the autonomic nervous system responsible for?

MedullaCerebrum

Cerebellum

InvoluntarySensory: Receives

informationTemp, 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

Volunta

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Michael J. Fox http://www.anyclip.com/movies/back-to-

the-future/the-flux-capacitor/