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/