The Nervous System:

Master Control

Explore: How do you keep you balance??

(Balance Beam / marbles) What were some of the things you had to

watch out for?? What kinds of body adjustments do you

have to make to keep yourself in balance?

Think of a sport. (bicycling / ice skating / ballet / etc):

describe the importance of maintaining balance when performing this sport.

Explore: How do you keep you balance??

8-1: The role of your nervous system

The body system that made adjustments for your balancing acts is called your nervous system.

The nervous system is composed of the brain, spinal cord and all the nerves that connect those 2 structures with other parts of the body.

The nervous system has 3 major functions.

First is receives information about the environment and the other parts of the body.

Then it interprets the information it receives.

Finally is makes the body respond to this information.

The nervous system receives signals: called stimulus.

(this can be from inside or outside your body)

When our nervous system reacts to this stimulus it is called a: response.

The nervous system has 3 major functions.

This is how an organism interacts with the environment.

Consider what happens when you hear a phone ring.

Nerves from your ear send a message to your brain.

Your brain interprets this information as the sound of a phone ringing.

Then your brain sends a message to your arm muscles.

The muscles then contract, and you reach out to lift the phone.

Sports require an instant response to a multitude of stimuli.

Name some examples of a sports stimuli and the response:

Neurons: Your Body’s Relay Team

Impulses travel throughout the nervous system, but it does this via a sort of “relay team” process.

Neurons make up that team.

Neurons: Your Body’s Relay Team

A neuron, or nerve cell, is a basic unit of the nervous system

which is made up of a cell body, and branching dendrites that carry

electrical impulses to the cell body.

The cell body which is the largest part, directs the action of the cell.

The axon then carries these messages away from the cells body.

Axons end in a network of tiny branches. When the impulses reach the end of the

axon, they come to a small space, a synapse.

Neurons: Your Body’s Relay Team

A neuron carries information from one location to another.

Sensory neurons pick up information from the environment.

Motor neurons carry information to muscles or glands, causing them to act.

Interneurons, also called associate neurons, carry information between 2 other neurons.

Neurons: Your Body’s Relay Team

Demonstration: 4 students & a note.

Each student creates a stimulus (a signal) to get the next student’s attention (such as tapping the shoulder).

The students pass the note from one person to the next.

The note is a nerve impulse, the signal (shoulder tapping) is a stimulus, and taking the note is the response.

A typical neuron is shown in the picture.

A typical neuron is shown in the picture.

A typical neuron

The cell body contains the nucleus and most of the cytoplasm.

Many long threadlike dendrites branch from the cell body.

A long, thin fiber called an axon also extends from the call body.

The axon is often coated with myelin, a white, fatty material.

A typical neuron

Axons are sometimes called nerve fibers. These fibers occur in bundles called nerves. The dendrites receive stimulation from the

environment or from the body. If this stimulation is strong enough, a nerve

impulse, or message, is generated in the axon.

The impulse travels along the axon. From the end of the axon, a signal passes to a muscle, a gland, or the dendrites of another neuron.

A synapse is the junction of an axon and the structure with which it communicates.

The axon does not actually touch the muscle, gland, or dendrites. There is a space of about .00002 mm between the axon and the next structure.

A typical neuron

Demonstration: (Dominoes)

Compare the movement through the domino pattern to the transmission of a nerve impulse:

It is when these neurons are grouped together that they form what we call: nerves.

Nerve impulses are either heading for the brain or leaving it.

8-2: The Parts of Your Nervous System

Neurons make up the nervous system. The nervous system is divided into 2

parts. The central nervous system includes

the brain and the spinal cord. The peripheral nervous system contains

all the nerves that lie outside the central nervous system.

The Nervous System’s 2 Parts

The Central Nervous system

Both the brain and the spinal cord are covered by 3 protective membranes known as the meninges.

The space between the 2 inner meninges is filled with cerebrospinal fluid.

The Central Nervous system

This fluid is produced in cavities within the brain.

From there the fluid drains into blood vessels in the brain.

Cerebrospinal fluid cushions the brain and spinal cord against shock.

It also removes waste materials from the brain.

The Central Nervous system

The nervous tissue of the brain and spinal cord lies under the meninges,

The outer portion of the brain tissue is gray.

Beneath the gray layer,the brain is white. In contrast, the spinal cord appears white

on the outside and gray on the inside.

The Brain: Operator of the Nervous System

The processing of the stimuli that your body receives every second of every day is done by the central nervous system.

The central nervous system is made up of the brain and the spinal cord.

The brain, protected by your cranium or skull, is divided up into 3 parts which are:

1.The cerebrum: which is the largest part of the brain.

The brain of the human contains about 12 billion neurons.

Of the 12 billion, about 9 billion are contained in the cerebrum.

It carries out the functions such as memory, thought and speech.

The Brain: Operator of the Nervous System

It receives nerve impulses from your skin, eyes, ears, nose, and tongue,

and changes them into touch, sight, sound, smell & taste.

It also sends out signals that control many muscles.

This is where the senses are processed.

The cerebrum:

2.The cerebellum:

This part processes the messages of an activity,

sends messages to the cerebrum in what order and how much force is needed for the muscles to carryout needed actions,

and also helps you maintain balance. It helps with the voluntary activities such as

muscle & skeletal movement. The cerebellum helps maintain the balance of

your body.

3. The Brain stem (medulla oblongata):

All nerve impulses to and from the brain pass through the brain stem.

It is the part of the brain that connects with the spinal cord.

It is also responsible for involuntary activities such as control over digestion, heartbeat, breathing, etc.

Involuntary body activities are usually those that are crucial for survival.

(other parts for consideration)

The thalamus lies beneath the cerebrum and is a sensory relay station.

It receives impulses from most sensory neurons entering the brain.

The thalamus also screens stimuli. It prevents sensory overload.

The hypothalamus lies beneath the thalamus. It controls important sensations involved in

maintaining homeostasis, such as hunger and thirst.

Temperature, water balance, and blood pressure are also controlled by the hypothalamus .

In addition, it also regulates the release of many hormones.

(other parts for consideration)

4. The spinal cord.

It runs the length of the backbone and is protected by vertebrae and discs made of cartilage.

It basically extends the brain stem down the back.

Is acts as the connections between the brain and the parts of the body.

Brain Diagrams

Brain Diagrams

The side of the brain that is dominant can affect how people approach problem solving.

In partners: 1 person: writes a short paragraph about their favorite sport.

The other person is to observe how the person writes .

Activity:

How did they hold the pencil. __________ Where is the pencil in relationship to the paper. ____ Is the pencil straight ahead with the hand held under

the line: ___________ or is the pencil curved around with the point facing

toward the writer and the hand above the line of writing? _______________________

Conclusions: Right brained or left brained?______ What does this mean to this person? Is it accurate?________________________

Activity:

One hemisphere of the brain is dominant over the other.

The left hemisphere of the brain is usually dominant.

Left-hemisphere dominance causes a person to be right-handed.

In most people, an area in the left hemisphere controls speech.

The left side of the brain is also specialized for mathematics and logic.

Activity:

The right side is usually specialized for art and music.

The side of the brain that is dominant can affect how people approach problem solving.

Studies have shown that usually the left side of the brain solves complicated problems step by step.

The right side of the brain is intuitive, tending to see the whole picture rather than the individual pieces.

Activity:

Is the pencil straight ahead with the hand held under the line, if so, that person has a dominant left brain.

Is the pencil curved around with the point facing toward the writer and the hand above the line of writing?

That person has a dominant right brain.

Activity: