The Nervous SystemThe Nervous System

I. IntroductionI. Introduction

The basic functional unit of the nervous

system is the neuron

Neuron Specialized cell that transmits

information throughout the body.

The brain, spinal cord, and nerves are all

composed of neurons.

Brain…a mass of over 100 billion

neurons

Nerves…long bundles of neurons

A. Neuron StructureA. Neuron Structure

1. Dendrites Receive incoming impulses, carry them towards the cell body.

2. Cell Body Contains nucleus & other organelles

3. Axon Transmits impulses away from cell body.

4. Myelin Sheath Lipid layer surrounding the axon that speeds transmission of impulse

5. Nodes of Ranvier Gaps in the myelin sheath. The impulse jumps from one node to another.

6. Axon Terminal Sends impulse to muscle, gland, or dendrite of another neuron.

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B. Neuron FunctionB. Neuron Function Communication throughout the body occurs

through a network of neurons. Axon of one neuron communicates with

dendrite of the next neuron Neurons don’t touch—gap between neurons is

called a synapse. How does it work?

Impulse travels down neuron Neurotransmitters travel across synapse Triggers impulse in next neuron.

Homework AssignmentHomework Assignment

1. Diagram of neuron on page 1013. Draw Label

Dendrites, Axon, Cell Body, Myelin Sheath, Nodes of Ranvier, Axon Terminals, Direction of Impulse (use arrows)

Color

2. Diagram of brain on page 1005. Draw Label (4 lobes and functions of each) Color

II. Organization of the Nervous II. Organization of the Nervous SystemSystem

Nervous System

Central Nervous System

Peripheral Nervous System

Brain Spinal Cord

MotorDivision

Sensory Division

Autonomic Nervous System

Somatic Nervous System

SympatheticDivision

Parasympathetic Division

A. Central Nervous SystemA. Central Nervous System

1.Brain:

Control center responsible for thought, feelings, emotions, memory, homeostasis, etc.

Specific areas of the brain are responsible for different functions.

Let’s take a look…how do they know what part does what?

1. Cerebrum Largest portion, highly folded, divided into 2 hemispheres & 4 lobes

2. Thalamus Directs incoming information to correct area of cerebrum

3. Hypothalamus Homeostasis, hormone production

(Both the thalamus and hypothalamus are also involved in memory, motivation, and emotion)

4. Midbrain Relay center

5. Pons Relay center

6. Medulla Oblongata Relay center, heart rate, respiration rate

7. Cerebellum Coordination of muscle action

2. Spinal Cord: Column of nerve tissue that starts at

the medulla and runs through vertebrae.

Connects brain with nerves in the body Responsible for reflex actions

(involuntary, self-protective movements not involving the brain)

B. Peripheral Nervous SystemB. Peripheral Nervous System

All nerves beyond brain & spinal cord. Two major divisions:

1. Sensory Division: Acquires information from the

environment and relays it back to the brain.

Involves sense organs (ears, eyes, nose, pain receptors, etc.)

Number your paper from 1-25. When you see a word, write down

the color you see.

Example:

Green

You should write down BLUE

• The words will come pretty fast, so get ready to write.

• I suggest that you abbreviate each color so that you don’t have to write out the whole word.– Ex: Black = bla, Blue = blu, yellow = y

RedBlueGreenBlueBlackYellowGreenPinkRedBlueBlueBlackYellowGrayGreenBlueBlackOrangePinkBrownGreenRedBlueRedOrange

How

’d y

ou

do?

1. Green2. Red3. Yellow4. Green5. Blue6. Black7. Orange8. Blue9. Green10. Red11. Red12. Purple13. Gray

14. Yellow15. Red16. Purple17. Yellow18. Black19. Black20. Green21. Red22. Blue23. Red24. Blue25. Yellow

Could this object be built?

How many black dots can you count?

What is moving?

Which rope is continuous?

2. Motor Division:

Brain’s response to sensory information Two major divisions:

a. Somatic: Control the movement of skeletal muscles Mostly voluntary

b. Autonomic: Control the movement of smooth muscles (blood

vessels, organs) Involuntary (respiration, HR, homeostasis) Two major divisions:1. Sympathetic Readies the body to respond to danger (HR increases, adrenaline, pupils dilate)2. Parasympathetic Conserves energy, restores homeostasis (Pupils constrict, HR slows)

Choose the division of the nervous system Choose the division of the nervous system responsible for the actions below. responsible for the actions below.

1.1. Flexing Your Bicep Flexing Your Bicep Motor or Sensory? Motor or Sensory?

2.2. Digesting Your Breakfast Digesting Your Breakfast Somatic or Somatic or

Autonomic?Autonomic?

3.3. Adrenaline Rush Before A Game Adrenaline Rush Before A Game

Sympathetic or Parasympathetic?Sympathetic or Parasympathetic?

4.4. Pulling Your Hand Away From The Stove? Pulling Your Hand Away From The Stove?

Brain or Spinal Cord?Brain or Spinal Cord?

5.5. Doing Five Jumping Jacks Doing Five Jumping Jacks Cerebellum or Cerebellum or

Medulla?Medulla?

Temporal Lobe

Hearing

Taste

Parietal Lobe

Sensory (Touch)

Frontal Lobe

Intellect

Motor Function

Speech

Occipital Lobe

Vision