1. THE NERVOUS SYSTEM HOW DOES IT WORK?
Video:

2. Purpose:
Controls and coordinates the body’s response to changes in the environment
Why?
Failure to respond may result in disease or death
How?
Uses neurons to send electrical messages (impulses)

3. A. Stimulus and Response
i. stimuli is a change in the internal or external environment of the body
Receptors are used to detect stimuli (sensory organs) (ie. Ears, skin, nose, mouth)
ii. response is the way you react to a certain stimuli
Effectors are organs that produce the response (ie. muscles or glands)

4. Stimuli Response Bright light Blink, squint hunger
Salivate, stomach growls
Wasp or bee
Swat, move away

5. Neurons: (nerve cells)
nerve cells specialized for receiving and transmitting impulses/signals
functioning units of the nervous system

6. 1. Nerve cell (neuron) “DCATS” – order of impulse
1 = dendrite
Detects stimulus
Starts impulse
2 = cyton (cell body)
Has nucleus
3 = axon (covered by myelin sheath)
Carries nerve impulses
sheath insulates axon
4 = endbrushes
Terminal branches
Release neurotransmitters across synapse to another neuron
5 = synapse
The space between neurons where impulses “jump” from one neuron to the next D C A T 5 S

7. Neurotransmitter
Chemicals used to help transfer the impulse across the synapse
Found in tiny sacs (vesicles) at the axon terminals

8. 3. Nerves – bundle of neurons that transmits impulses 4
3. Nerves – bundle of neurons that transmits impulses 4. Types of neurons
Sensory
From sense organs (eyes, nose, skin, ears, tongue) to brain/spinal cord
Interneurons
Interconnect other two types
Found in brain and spinal cord
Motor
From brain/spinal cord to muscles/glands

9. Types of neurons sensory neuron (from senses) interneuron
(brain & spinal chord)
motor neuron
(to muscle)

10. Reflex Arc (Loop)
Quick involuntary action that doesn’t involve the brain
Neurons may release chemicals to stimulate each other, or these chemicals may be released to stimulate a muscle or gland. 
An example of a muscle being stimulated by a neuron appears after the reflex path pictured in number four in the diagram.
Receptor
Effector

11. “RSIME”- order of stimulus
R- RECEPTOR (DETECTS STIMULUS)- SENSORY ORGAN
S- Sensory
I- INTERNEURON
m- MOTOR NEURON
E- EFFECTOR (RESPONDS TO STIMULI)- MUSCLE OR GLAND

12. The Nervous System How is it made up?

13. Divisions of the Nervous System
The nervous system is divided into 2 main parts:
The Central Nervous System (CNS)
The Peripheral Nervous System (PNS)

14. CNS
cerebrum: center for voluntary activity interprets sensory impulses, initiates some motor activities, and responsible for memory, thinking and reasoning
cerebellum: coordinates motor activities and aids in maintaining balance
medulla: controls involuntary activities such as breathing, heartbeat, blood pressure and peristalsis (is part of the brain stem)
Brain stem
Connects brain to spinal cord
Consists of
Medulla oblongata (heart rate, etc)
SPINAL CORD

15. Central Nervous System (CNS) Consists of the brain & spinal cord
2. Peripheral Nervous System (PNS)
Includes all the spinal nerves TWO FUNCTIONS
a) TRANSFER IMPULSES FROM SENSE ORGANS  CNS
b) TRANSFER IMPULSES FROM CNS  MUSCLES OR GLANDS

16. D. Nervous System Disorders
Very serious: the nervous system CANNOT repair itself
1. Stroke – cerebral bleeding or clot
2. Parkinson’s disease – missing dopamine (neurotransmitter); movement related problems (ie. Shaky)
3. Alzheimer’s – interference w/ brain neurons causing cognitive problems (memory loss, recognition, etc)
4. Meningitis – bacterial or viral