The Nervous System

I. 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 Structure 1. 1.Dendrites  Receive incoming impulses, carry them towards the cell body Cell Body  Contains nucleus & other organelles 3. 3.Axon  Transmits impulses away from cell body Myelin Sheath  Lipid layer surrounding the axon that speeds transmission of impulse 5. 5.Nodes of Ranvier  Gaps in the myelin sheath. The impulse jumps from one node to another Axon Terminal  Sends impulse to muscle, gland, or dendrite of another neuron

B. 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 Assignment Diagram of neuron on page   Draw   Label  Dendrites, Axon, Cell Body, Myelin Sheath, Nodes of Ranvier, Axon Terminals, Direction of Impulse (use arrows)   Color Diagram of brain on page   Draw   Label (4 lobes and functions of each)   Color

II. Organization of the Nervous System Nervous System Central Nervous System Peripheral Nervous System BrainSpinal CordMotor Division Sensory Division Autonomic Nervous System Somatic Nervous System Sympathetic Division Parasympathetic Division

A. Central Nervous System 1. 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. 1.Cerebrum  Largest portion, highly folded, divided into 2 hemispheres & 4 lobes 2. 2.Thalamus  Directs incoming information to correct area of cerebrum 3. 3.Hypothalamus  Homeostasis, hormone production (Both the thalamus and hypothalamus are also involved in memory, motivation, and emotion) 4. 4.Midbrain  Relay center 5. 5.Pons  Relay center 6. 6.Medulla Oblongata  Relay center, heart rate, respiration rate 7. 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 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 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

Red Blue GreenBlueBlackYellow Green PinkRedBlue Black Yellow Gray GreenBlueBlack Orange Pink BrownGreenRed Blue Red Orange

How’d you do? 1.Green 2.Red 3.Yellow 4.Green 5.Blue 6.Black 7.Orange 8.Blue 9.Green 10.Red 11.Red 12.Purple 13.Gray 14. Yellow 15. Red 16. Purple 17. Yellow 18. Black 19. Black 20. Green 21. Red 22. Blue 23. Red 24. Blue 25. 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 responsible for the actions below. 1. Flexing Your Bicep  Motor or Sensory? 2. Digesting Your Breakfast  Somatic or Autonomic? 3. Adrenaline Rush Before A Game  Sympathetic or Parasympathetic? 4. Pulling Your Hand Away From The Stove?  Brain or Spinal Cord? 5. Doing Five Jumping Jacks  Cerebellum or Medulla?

Temporal Lobe Hearing Taste Parietal Lobe Sensory (Touch) Frontal Lobe Intellect Motor Function Speech Occipital Lobe Vision