You smell a delicious aroma. You walk into the kitchen and see a bag of popcorn in the microwave. You hear some kernels still popping. Then you think to yourself, “Snack time!” Which body systems enabled you to smell, walk, see, hear, and think? How did each system play a part in your response? How do organs and other structures enable the nervous system to function?

Section 15.1: How the Nervous System Works • What are the functions of the nervous system? • What is the structure of a neuron and what kinds of neurons are found in the body? • How do nerve impulses travel from one neuron to another?

Jobs of the nervous system: • The nervous system receives information (Stimulus) about what is happening both inside and outside our bodies. • It directs how we react to our environment (Response) • 3. It maintains homeostasis.

Kinds of Neurons • Sensory Neurons: carries messages from receptors to the interneuron within the brain or spinal cord. • Interneurons: connect sensory and motor neurons. (brain and spinal chord) • Motor Neurons: sends impulses to muscles.

The Structure of a Neuron: • Cell body= with a nucleus • Dendrite = an extension that carries messages to the cell body. • Axon = carries messages away from the cell body.

How a Nerve Impulse Travels • A nerve impulse must cross the gap between the axon and the next structurethis is the synapse • The axon tips release chemicals that carry • the impulse across • the gap.

Section 15.2: Divisions of the Nervous System • What are the structures and functions of the central nervous system? • What are the structures and functions of the peripheral nervous system? • What is a reflex? • What are two ways in which the nervous system can be injured?

Divisions of the Nervous System • The Central Nervous System: • Control center of the body. • Brain and Spinal Cord • The Peripheral Nervous System: • Branches out and connects to the CNS • Somatic nerves control voluntary actions • Autonomic nerves control involuntary actions • The Brain: • 100 billion neurons (all interneurons) • 3 main regions • Cerebrum: • largest • Two halves • Think/remember/speak • The senses • 2. Cerebellum: • Balance • Posture • Brainstem/Medulla • Controls involuntary processes • Heartbeat/blood pressure • Breathing

Divisions of the Nervous System • The Central Nervous System: • Control center of the body. • Brain and Spinal Cord • The Peripheral Nervous System: • Branches out and connects to the CNS • Somatic nerves control voluntary actions • Autonomic nerves control involuntary actions

Central Nervous System • The central nervous system is the control center of the body. It includes the brain and spinal cord.

Peripheral Nervous System • Branches out and connects to the CNS • Somatic nerves control voluntary actions • Autonomic nerves control involuntary actions

The Brain • There are three main regions of the brain • 1. Cerebrum: • largest • Two halves • Think/remember/speak • The senses • 2. Cerebellum: • Balance • Posture • 3. Brainstem/Medulla • Controls involuntary processes • Heartbeat/blood pressure • Breathing

Reflexes • A reflex is an automatic response that occurs very rapidly and without conscious control.

Section 15.3: Sight and Hearing • How do your eyes enable you to see? • How do you hear and maintain your sense of balance?

Vision • You eyes respond to the stimulus of light. They convert that stimulus into impulses that your brain interprets, enabling you to see.

Vision • Light coming from an object enters your eye and is focused by the lens. • The light produces an upside-down image on your retina. • Receptors in your retina then send impulses to your cerebrum, which turns the image right-side up.

Hearing and Balance • Your ears are the sense organs that respond to the stimulus of sound. Ears convert the sound to nerve impulses that your brain interprets.

Sound Intensity • Sound intensity, or loudness, is measured in units called decibels. The threshold of hearing for the human ear is 0 decibels. For every 10-decibel increase, the sound intensity increases ten times. Thus, a 20-decibel sound is ten times more intense than a 10-decibel sound. A 30-decibel sound is 100 times more intense than a 10-decibel sound. Sound levels for several sound sources are shown in the bar graph.

Decibels, or sound level; type of sound Reading Graphs: What unit of measure is represented on the y-axis? What is represented on the x-axis? Sound Intensity

Section 15.4: Smell, Taste, and Touch • What are the functions of the nervous system? • What is the structure of a neuron and what kinds of neurons are found in the body? • How do nerve impulses travel from one neuron to another?.

Touch • Touch receptors are the nerve cells that tell your brain about tactile sensations. There are two groups • (1) mechanoreceptors that tell you about sensations of pushing, pulling or movement, • (2) thermoreceptors that tell you about sensations of temperature.

SMELL

Smell and Taste • The senses of smell and taste work closely together. • Both depend on chemicals in food or in the air. • The chemicals trigger responses in receptors in the nose and mouth.

Section 5: Alcohol and Other Drugs • What are the functions of the nervous system? • What is the structure of a neuron and what kinds of neurons are found in the body? • How do nerve impulses travel from one neuron to another?

Illegal (Controlled) Drugs Marijuana Cocaine Methamphetamine Hallucinogens Narcotics Depressants Steroids Inhalants

Tobacco • Kills More than all Other Drugs Combined! 430,000 + Every Year! • Second Hand Smoke • Cancer, Heart Attacks • Smokers’ Face/Breath/Teeth • No Safe Way To Use

Alcohol • Alcohol is a drug found in many beverages, including beer, wine, cocktails, and hard liquor. Alcohol is a powerful depressant and affects every system of the body.

Alcohol • Health Risk • Fitness for Duty • Accidents • Drinking & Driving • Violence / Family • Underage Drinking Excessive Drinking can Cause Problems with... Work, Family, Friends, Society, and Self ALCOHOL IS A DEPRESSANT-IT SLOWS THE ACTIONS OF THE CENTRAL NERVOUS SYSTEM.

Marijuana • Strong • Available • 30 Million Users • Reputation as a “safe” drug • 15 Times Stronger than ‘70s • Keeps People from Achieving Their Potential • Often Laced w/ Other Drugs • Hooks into Fat Cells

Cocaine & Methamphetamine • Increases • Heart Rate • Blood Pressure • Activity • Insomnia, • Euphoria followed by Depression • Neural Disruption • “Wired”, Addiction

COCAINE vs. Methamphetamine Crack vs. ICE Coke=> Shorter, Bigger Surge Ice=> Voices & Bugs, Paranoia, Violence

Cocaine • Highly Addicting • Dealing & Stealing • High Dying Potential • Often in Up/Down Combos => w/ Heroin

Methamphetamine - “Ice” • High Potential for Violence, Addiction, & Death • The Drug of Choice in Hawaii • 2-3 Months Addiction Time • Losing One’s Mind & Will

Ecstasy (Methamphetamine) vs. Herbal Ecstasy (Ephedrine) Ecstasy: Powerful Stimulant & Hallucinogen

Hallucinogens Therapeutic Use Street Abuse Army Testing Begins in 1989 Users Easy to Spot Effects= Focus, Distortions, Nausea, Disorientation, Performance , Communications , Panic, TRAUMA

Hallucinogens Effects: Focus X, Distortions, Nausea, Disorientation, Performance X, Communications X, Panic, TRAUMA

Depressants 1950’s - Sleeping Pills 1960’s - Barbiturates (Seconal & Phenobarbital) Slowed Down, Sleepy; Impaired Thinking, Coordination; Mood Swings, Stressed heart

NARCOTICS The Naturals: Opium, Morphine, Heroin The Synthetics: Percodan, Demerol, Codeine

Inhalants The Hidden Addiction: Readily Available => Gas, Glue, Sprays, Paint, Polish, Cleaning Fluid, Medications, Poppers, White Out, Scented Pens....

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