Nervous System: Part I

The Nervous System Your body’s communication’s network &

control center Peripheral Nervous System (PNS)-

gathers info from inside & outside the body

Central Nervous System (CNS)-receives this info & initiates a response-composed of the brain & spinal cord

Messengers & receivers of these transmissions are NEURONS (nerve cell)

Three Types of Neurons Sensory-carry from

sense receptors to CNS (5 senses)

Motor-carry signals from CNS to muscles or glands

Interneurons-carry electrical connections within the CNS

Functions of Neurons Cell body-contains nucleus & cell

membrane Dendrites-branching projections of the cell

body, carry impulses into the cell. Axon-Threadlike extension carries impulses

to & from the cell, at the end of axon is the axon terminal

Myelin Sheath-Insulates the axon & speeds up transmission of the impulses

Synapse-point of contact at which impulses are passed from one cell to another

Electrical impulse

The Nerve Impulse

Let’s draw neurons! Look at the drawing on

page 517 of your health book.

You will need 4 different colors markers/pencils, for the:

cell body dendrites axon/terminal synapse

Draw your neuron on a piece of paper

color and label the parts

Right Brain--- Left Brain

Sitting at your desk, lift your right foot off the floor and make clockwise circles

Now, while doing this, draw the number "6" in the air with your right hand. [Your foot will likely change direction, and there's nothing you can actually do about it.]

Reflex Action (Unconscious) If the safety of our body

requires a very quick response, the signals may pass directly to a motor neuron for instant, unthinking action. This is a reflex action. Signals sent via the spinal cord

List as many examples of a reflex action as you can:

http://www.bbc.co.uk/schools/gcsebitesize/biology/humansasorganisms/4nervoussystemrev4.shtml

Part II: Nervous System

Voluntary Actions (Conscious Act) Impulses passed via the

brain What is the chain of

events that happens from the instant you hear the phone ring until you pick up the phone?

Every time a stimulus—such as a ringing telephone—is detected, the body's three kinds of neurons send a nerve impulse through the nervous system.

Nerve Impulse Activity In groups put the following path

of a nerve impulse in the correct order:

1.The nerve impulses pass to interneurons in the brain.

2.Receptors in your ear pick the sound of a ringing phone

3.Muscles in the arm carry out the response and you reach to pick up the phone

4. Impulses travel along motor neurons to the muscles

5. Receptors trigger nerve impulses in sensory neurons

6. Your brain interprets the impulses from many interneurons and you realize the phone is ringing. Your brain also decides that you should answer the phone.

Correct order… 2. Receptors in your ear pick the sound of a

ringing phone 5. Receptors trigger nerve impulses in sensory

neurons 1. The nerve impulses pass to interneurons in

the brain. 6. Your brain interprets the impulses from

many interneurons and you realize the phone is ringing. Your brain also decides that you should answer the phone.

4. Impulses travel along motor neurons to the muscles

3. Muscles in the arm carry out the response and you reach to pick up the phone

The Brain

Largest, most complex part of the nervous system

Weighs 3 pounds, contains billions of neurons

Without oxygen it can only last 4-5 minutes

Cerebrum

Forms our intellect & personality Divided into two hemispheres Left-language & logic Right-imagination & emotional

responses Does not fully develop until late

teens or early-mid 20s!!!

Phineas Gage

If an explosion sent a steel rod through your head, would you be able to get up? Would you be able to walk and talk? Could you tell your doctor what happened to you? Amazingly, Phineas Gage did! But, could he make a complete recovery with a big hunk of his brain missing?