-The body’s master controlling and communication system, used for rapid relaying of information

By Morgyn Graber and Hailey Holland

1) Sensory Input: Monitors changes occurring both inside and outside the body2) Integration: Makes decisions about what should be done at each moment3) Motor Output: Activates muscles and glands

of the nervous system

Neurons (Nerve Cells)

- transmit messages (impulses) to different parts of the body

• Cell body: metabolic center of neuron• Dendrites: neuron processes that convey incoming messages toward cell body• Axon: nerve impulses that conduct messages away from cell body Can have hundreds of dendrites, but only one axon

Dendrites

Cell Body

Axon

Spinal Cord- a continuation of the brain stem enclosed with in the vertebral column- extends from the foramen magnum

● Provides a two-way conduction pathway to and from the brain● A major reflex center● 31 pairs of spinal nerves arise from the cord and exit from the vertebral column to serve the body area close by Gray Matter

White Matter

Gray Matter● Looks like an “H” or a butterfly in cross section● Surrounds the central canal of the cord● Special neurons with specific sensory functions are located here, and if they are damaged, sensation in the body area served will be lost● Motor neurons, that control voluntary movements, of the somatic nervous system are also located here

White Matter● Composed of myelinated fiber

tracts● Divided into the posterior, lateral, and anterior columns which each contain fiber tracts made up of axons with the same destination and function● Posterior column contains tracts that cacrry sensory information to the brain● Lateral and Anterior tracts contain motor tracts that carry impulses from the brain to skeletal muscles

Cerebrum

Functions:•Thought •Voluntary movement•Language•Reasoning •Perception

- a sheet of tissue that makes up the outer layer of the brain- has bumps (gyri) and grooves (sulci)- the right and left sides of the cerebral cortex are connected by a thick band of nerve fibers called the “corpus callosum”

The cerebrum is the LARGEST part of the brain.

Cerebellum

Functions:• Movement• Balance • Posture

- located behind the spinal cord- divided into two hemispheres with a cortex surrounding each

Brain StemFunctions: • Breathing• Heart rate• Blood pressure

- the area of the brain between the thalamus and the spinal cord

Medulla-lower portion of the brain stem• Deals with autonomic functions (breathing, blood pressure, etc)• Cardiac center controls heart rate• Transmits ascending and descending nerve fibers between the spinal cord and the brain

Pons-the upper segment of the brain stem• Contains nerve fibers that connect the two halves of the cerebellum • Relays sensory information between cerebellum and cerebrum• Aids in relaying other messages to the brain• Regulates respiration

DIVISIONS OF THE NERVOUS SYSTEM

● The functional classification scheme is concerned with the subdivisions of the Peripheral Nervous System: the Somatic Nervous System and the Autonomic Nervous System

● Structural Classification of the Nervous System has TWO subdivisions: the Central Nervous System and the Peripheral Nervous System

● The Autonomic Nervous System itself has two further subdivisions: the sympathetic and parasympathetic divisions

Central Nervous System (CNS)

● Consists of the brain and spinal cord, which occupy the dorsal body cavity and act as the integrating and command centers of the nervous system

● Interprets sensory information and issues instructions based on past experience and current conditions

Peripheral Nervous System (PNS)

• Consists mainly of the nerves that extend from the brain and spinal cord

Spinal Nerves carry impulses to and from the spinal cord

Cranial Nerves carry impulses to and from the brain

Both types of nerves serve as communication lines and link all parts of the body by carrying impulses from the sensory receptors to the CNS and from the CNS to the appropriate glands or muscles

Somatic Nervous System (SNS)

Autonomic Nervous System (ANS)Motor Divisions of the Peripheral Nervous

System• Allows for voluntary control of skeletal muscles

• Also controls skeletal muscle reflexes

• Regulates involuntary events

• Composed of a special group of neurons that control activity of cardiac and skeletal muscles as well as glands

•Helps maintain the body’s homoeostasis

Sympathetic SystemParasympathetic SystemDivisions of the Autonomic Nervous

SystemBOTH:

• Bring about opposite effects: what one stimulates, the other inhibits

• Serve same organs

• Counterbalance each other’s activities to keep the body working smoothly

SYMPATHETIC:

• “Fight or Flight” System

• Mobilizes body during extreme situations (fear, rage, etc.tc)

• Increases blood pressure, blood glucose levels, etc., to get your body ready to handle extreme situations

PARASYMPATHETIC:

• “Resting and Digesting” and “Housekeeping” System

• Allows the body to “unwind” and conserve energy

• Most active when body is at rest and non-threatened

• Concerned with promoting hormone secretion, digestion, and elimination of waste

THE

EFFECTS

OF

DRUG

AND

ALCOHOL

USE

Alcohol and the Nervous System Low Doses of Alcohol can Cause:

o Relaxation

o Impaired concentration & Reaction Time

o Slow Reflexes

o Reduces CoordinationMedium Doses of Alcohol can Cause:

o Slurred Speech

o Drowsiness

o Altered Emotions

High Doses of Alcohol can Cause:

o Vomiting

o Difficulty Breathing

o Unconsciousness

o Coma

Alcohol:

is a Central Nervous System Depressant

affects the Reticular Formation, Spinal Cord, Cerebellum, Cerebral Cortex, and Neurotransmitter Systems

LSD and the Nervous System

LSD can cause: A feeling of “strangeness” Vivid colors Hallucinations Confusion, panic, and anxiety Emotional distress Distortion of senses, time, and space Increase in heart rate and blood pressure Chills Muscle weakness

LSD interrupts the neural pathways and mimics a common neurotransmitter, serotonin. The affects of LSD are due to stimulation of seratonin receptors on neurons

Rohypnol (Roofies) and the Nervous System

Rohypnol can: Suppress Central Nervous System Produce amnesia and muscle relaxation Lower inhibitions

(Valium and Xanax are two common types of Rohypnol)

Rohypnol influences behavior by interacting with receptors on neurons and neurotransmitters in the brain

Marijuana and the Nervous System

•Marijuana can cause:

•Relaxation

• Reduced Coordination

•Delusions/Disorientation

• Impaired Memory

• Disruption in attention

• Altered sense of time and space

THC, the main component in marijuana, causes altered states of consciousness. It alters all areas of the brain dealing with memory, including the hippocampus, cerebral cortex, cerebellum, substantia nigra, and globus pallidus.

Cocaine and the Nervous System

Euphoria

Excitement

Dizziness

Headache

Anxiety

Depression

Cocaine is a stimulant with a similar chemical makeup to a common neurotransmitter, and the increased levels of this chemical cause:

DISEASES & DISORDERS

A microscopic image of Huntington's Disease

Epilepsy

-a chronic disorder of cerebral function characterized by periodic seizures

Causes are unknown, but predisposing factors are family history, head injury, alcohol withdrawal, infections, and abnormalities of the brain

Narcolepsy

Symptoms:

•Excessive daytime sleepiness

•Cataplexy (sudden muscular weakness without unconsciousness)

•Sleep paralysis (a feeling that one cannot move)

•Hallucinations

•“Sleep attacks” at any time

Cause unknown, but can run in families

Treatment, including regular planned naps and the use of stimulant drugs can control symptoms

Multiple Sclerosis (MS)

- Causes the body’s immune system to attack the myelin sheaths that surround nerve cells resulting in damaged areas that are unable to transmit nerve impulses

Hard areas (plaques) develop around a neurons axon which disrupts the way messages are sent throughout the nervous system

Symptoms

•Loss of muscle strength and dexterity

•Problems with walking, balance, coordination

•Optical problems

•Pain

•Weakened immune system

Exact cause unknown; environment and genetic factors contribute

Tourettes Syndrome (TS)

Symptoms:

•Recurrent involuntary movement

•Vocal tics (grunts, barks, obscenities)

•Motor tic (shoulder shrugging, eye twitching, head jerking)

•Inherited

•No cure, symptoms can be treated, but with no guarantee

Diagnosis:

Determined by ruling out other diseases with similar symptoms by use of cat scan, mri, eeg, and blood test. If all come back negative to other diseases and you have a tic for more than a year, diagnosis is tourettes

Tics are believed to result from dysfunction in cortical and subcortical regions, the thalamus, basal ganglia and frontal cortex.

-neurological disorder

Huntington’s Disease (HD)- An inherited neurological

disorder

Symptoms:

•Dementia

•Jerky, random body movements

•Tics

•Poor coordination

•Depression

•Memory loss

•Mood swings

•Intellectual deterioration

No treatment

-damages neurons in the basal ganglia (especially the regions of the caudate nucleus and the globus pallidus)

A brain with Huntington’s Disease (top) compared to a normal brain

Neuroscience for Kids. Eric H. Chudler. 12-08-08.

[http://faculty.washington.edu/chudler/introb.html]

Fact Monster. Information Please. 12-09-08.

[http://www.factmonster.com]

Marieb, Elaine. Essentials of Human Anatomy and Physiology.

California: Pearson Education, 2006.