The Nervous System Chapter 13 Lesson 1 What Is The Role of the Nervous System

1. The Nervous System • Chapter 13 Lesson 1 • What Is The Role of the Nervous System • How Do the Parts of Your Nervous System Work • What Do Your Senses Do?

2. What is the role of the nervous system? • Receives information about what is happening both inside and outside your body • Directs how your body responds to this information • Helps maintain homeostasis Click!

3. Responding to Information STIMULUS Any change or signal In the environment that an organism can react to is called a _______ . Example: A buzzing fly RESPONSE After your nervous system analyzes a stimulus, it directs a __________ which is a reaction to the stimulus. Example: Swatting at the fly

4. Neurons Individual cells that carry information through your nervous system Click!

5. 13.1 The Nervous System Nerve Impulses Nerve • What is the message that a neuron carries that may occur as either electrical or chemical signals? • What is a bundle of nerve fibers called?

6. 13.1 The Nervous System • Structure of a Neuron • A neuron has one axon and many dendrites that extend from the cell body.

7. Dendrites Cell body Nucleus Axon Myelin Axon tips Parts of a neuron 1. Dendrites: “receivers” - there are many short parts of the neuron that pick up the impulse and carry it to the 2. Cell body (contains nucleus) 3. Axon: “sender” - one long part that sends the impulse away from the cell body. Myelin coats the axon and speeds up the impulse transmission.

8. 13.1 The Nervous System 3 Types of Neurons 1. Sensory neuron- picks up a stimulus and converts it into a nerve impulseand relays it to an . . . 2. Interneuron- carries an impulse to another neuron or to a motor neuron 3. Motor neuron- sends an impulse to a muscle or gland, enabling it to respond

9. Moving Impulses Between Neurons Synapse- the place where a neuron transfers an impulse to another structure

10. The Synapse At a synapse, (at the axon tips) the electrical signals carried through the neuron are changed into a chemical form. This change allows the signal to cross the gap and reaches the dendrites of another neuron and changes back to the electrical form. What would happen to an impulse if a neuron could not produce chemicals at a synapse? The impulse would not travel any farther in the body

11. The Central Nervous System • What directs movements, includes the brain and the spinal cord & acts like a traffic cop directing cars through busy intersections?

12. The Brain is the control center The spinal cord links the brain to the peripheral nerves The peripheral nerves send and receive impulses

13. The Brain

14. 13.1 The Nervous System, p. 502 Different regions of the brain receive and process different information. What are some examples of how you use each region of your brain shown in this chart? I am able to see things, study, and talk to my friends I don’t fall when I walk to class, and I can balance when I ride a bike I am constantly breathing and my heart is always beating

15. Peripheral Nervous System • What includes all the nerves outside of the central nervous system, which are like the car drivers?

16. The Peripheral Nervous System • Has 43 pairs of nerves • Twelve pairs begin in the brain (Cranial Nerves) • Other 31 pairs (the spinal nerves) begin in the spinal cord • One nerve in each pair go to the left side of the body and one to the right. • Each spinal nerve contains axons of both sensory and motor neurons

17. The Spinal Nerves • The spinal nerves leave the spinal cord through spaces between the vertebrae • Impulses travel on a spinal nerve in two directions- both to and from the central nervous system

18. Peripheral System – 2 groups of nerves • Somatic • Nerves that control the voluntary actions • Autonomic • Nerves that control the involuntary actions

19. Reflexes An automatic response that occurs rapidly without conscious control

20. What Do Your Senses Do? • Your eyes, ears nose, skin and mouth are specialized sense organs that enable you to get information from the outside world. • Each organ has sensory neurons that send impulses to brain

21. How you see • Light rays enter through pupil & pass through the lens • Muscles attached to the lens adjust its shape and focus light rays on the retina • Because the lens bends light rays, it produces and upside down image • The retina contains light-sensitive cells that produce nerve impulses that travel through the optic nerve to the brain • Brain turns image right side up and combines image from both eyes to produce a single image

22. The Nervous System, p. 505 The Eye: Light from an object produces an image on the retina. Click!

23. Taste & Smell • Work together & depend on chemicals in the air or food • Chemicals trigger responses in receptors • Nerve impulses travel to the brain

24. Sense Trivia • How many basic odors can your nose distinquish? • 50 • How many basic taste sensations can your tongue distinquish? • Only 5 What are they? • Sweet, sour, salty, bitter and umami (Meatlike) • You experience a wide variety of flavors since taste and smell work together multiplying the possibilities

25. How You Hear • Sound waves pass through the structures of the ear • and are carried by nerve impulses to the brain. • What are the names of the three bones of the middle ear?

26. Touch • Unlike the other senses, the sense of touch is not found in one place! It is in all areas of your SKIN!