The Nervous System

What is it?A highly complex organized

system that coordinates all of the activities of the body.

This system enables the body to respond or adapt to changes that occur both inside and outside the body.

Components of the Nervous System

BrainSpinal

CordNerves

Nerves

NERVES Are a combination

of many nerve fibers located outside the brain and spinal cord. Their function is to relay messages to all the body muscles and glands. (muscles power the body movements)

DIRECTIONS OF NERVE IMPULSES

Afferent (sensory) nerves carry messages from all parts of the body to the brain and spinal cord.

Efferent (motor) nerves carry messages from the brain and spinal cord to the muscles and glands.

Associative (internuncial) nerves carry both sensory and motor messages.

The Cell of the Nervous System

Neurons

The neuron is the Basic functional unit of the nervous system.

Humans have about 100 billion neurons in their brain ALONE.

3 Parts of a NeuronCell Body – contains the nucleus

(maintains the functionality of the cell)

Dendrite – (dendritic tree) carry impulse to cell body

Axon – a single nerve fiber carries impulse away from the cell

Myelin Sheath

Axons have a lipid or fat layer called the myelin sheath.

They increase the rate of impulse transmission and insulates and maintains the axon.

For communication between neurons to occur, an electrical impulse must travel down the axon to the synaptic terminal.

Impulses coming from one axon “jump” the synapse to get to the dendrite of another neuron, which will carry the impulse in the right direction.

SYNAPSES ARE spaces between the Dentrites and

the Axon.

What allows for the jump across the sypnase between dentrites and axons? ….

NEUROTRANSMITTERS – located at the end of each axon allow the nerve impulses to pass from one neuron to another. These messages (impulses are able to follow many different routes.

Information is moved around the brain, from nerve cell to nerve cell, by means of chemical substances, called neurotransmitters

Parts of the Nervous System

The nervous system is broken down into 2 major parts. Central Nervous System – consists of

the brain (encepha/o) and the spinal cord (spondyl/o)

Peripheral Nervous System – consists of the nerves.

subdivision: AUTONOMIC NERVOUS SYSTEM

AUTONOMIC NERVOUS SYSTEM

TWO PARTSSympathetic and

ParasympatheticThese two systems work

together to maintain a balanced state (homeostasis)

SYMPATHETICIn times of emergency, this

system prepares the body to act in two ways:

Fight or Flightby: Increasing

heart rate respirationblood pressure

PARASYMPATHETICThis system counteracts, the

actions of the sympathetic system BY slowing down the

Heart Rate

Respiration Rate

Lowering blood pressure

AND Increasing activity in the Digestive System

Central Nervous System

Consists of:Brain Spinal Cord

Brain HemispheresYour brain is divided into left and

right hemispheres.The right side of your brain controls

the left side of your body.The left side of your brain controls

the right side of your body.

Left Brain/Right Brain

The Brain The brain is a mass of nerve tissue well

protected by membranes and the cranium.

It is made up of several sections. Cerebrum Cerebellum Diencephalon Midbrain Pons Medulla oblongata

Sections of the Brain

Cerebrum

The largest and highest section of the brain.

The outer part is arranged in folds, called convolutions, and separated in lobes.

Functions of the Cerebrum

Reasoning Thought Memory Speech Sensation Sight Smell Hearing Voluntary body movement

Functions of the Cerebellum

Muscle coordinationBalancePostureMuscle tone

DiencephalonThe structure that lies between the

cerebrum and the midbrain.It contains two structures:

Thalmus- directs sensory impulses to the cerebrum.

Hypothalmus-regulates and controls many of the functions of the body.

Midbrain

The section located below the cerebrum at the top of the brainstem.

Major Function: conducting impulses between brain parts

Pons

The section located below the midbrain and in the brain stem.

Functions: Conducting messages to other

parts of the brain Certain reflex actions Assists with respiration

Medulla Oblongata

The lowest part of the brain stem.It connects with the spinal cord.Functions: Regulation of

Heartbeat Respiration Swallowing Blood pressure

Lobes of the Brain

Lobes of the brain - CreationWiki, the encyclopedia of creation science

Spinal Cord

Continues down from the medulla oblongata and ends at the first or second lumbar vertebrae.

It is surrounded and protected by vertebrae.

Functions of the Spinal Cord

Responsible for many reflex actions and for carrying messages to and from the brain to the nerves that go to the organs and glands.

MENINGESThere are three membranes that cover

and protect the brain and spinal cord.

1. Dura mater – outer layer

2. Arachnoid membrane – delicate and web-like

3. Pia mater – closely attached to the brain and spinal cord; contains the blood vessels that nourish the nerve tissure.

VENTRICLESThere are FOUR hollow spaces that

connect with each other and with the space under the arachnoid membrane.

The ventricles are filled with a fluid called:

CEREBR0SPINAL FLUID

This fluid serves as a shock absorber Carries nutrients, removes metabolic waste

Absorbed into the blood vessels of the dura mater, returned to the bloodstream via the arachnoid villi

DISEASES AND ABNORMAL CONDITIONS

Cerebral palsy – a disturburbance in voluntary muscle action and is caused by brain damage (due to lack of oxygen, birth injuries, prenatal rubella(german measles), and infections.

Cerebrovascular accident (CVA) (stroke) – cerebral hemorrhage due to an aneurysm or occlusion or thrombus.

Encephalitis – inflammation of the brain due to virus or bacterium or chemical agent.

Epilepsy – or seizure syndrome; abnormal electrical impulses in the neurons of the brain.

Hydrocephalus – an excessive accumulation of cerebrospinal fluid in the ventricles and sometimes, in the subarachnoid space of the brain.

Meninigitis – inflammation of the meniges of the brain and/or spinal cord due to bacterium, virus, fungus, or toxins (lead, arsenic, mercury)

Multiple sclerosis – (MS) chronic, progressive, disabling, condition due to degeneration of the myelin sheath in the CNS.

Neuralgia – nerve pain due to inflammation, pressure, toxins and other diseases.

Paralysis – results from a brain or spinal cord injury that destroys neurons and results in a loss of function and sensation below the level of injury. Hemiplegia – one side of the body Paraplegia – lower extremities Quadriplegia – upper and low extremities

Parkinson’s disease – chronic, progressive condition involving degeneration of brain cells; includes tremors

Shingles (herpes zoster) – acute inflammation of nerve cells caused by herpes virus; which also causes chicken pox.

RELATED CAREERS Acupressurist Acupuncturist Anesthesiologist Chiropractor Diagnostic imager Doctor of Osteopathic Medicine Electroencephalographic Technologist Electroneurodiagnostic Technologist Mental Health Technicians

Neurologist Neruosurgeon Physical Therapist Polysomnographic Technologist Psychiatrist Psychologist

Medical Terminology

Root word: myel/o denotes spinal cord or bone marrow

Myelocele hernail protrusion

Poliomyelitis gray; inflammation

Myelomalacia softening

Myeloplegia paralysis

Myelogenous produce/create

Root Word: encephal/o denotes brain (inside) combined with cephal/o: head

Encephalitis inflammation

Encephalogram picture-tracing x-ray

Encephalopathic disease; pertaining to

Encephaloma tumor

Encephalomalacia softening

Psychiatrics treatment

Psychasthenia without, strength

Psychology science, study of

Psychosomatic body, pertaining to

Psychophylaxis protection, prevention

Root Word: algia,algesia; denotes pain or ache

Cephalalgia headNeuralgia nervesArthralgia jointOtalgia earHyperalgesia above,excessAnalgesic without, pertaining toGastralgia stomachMyalgia muscleKinesalgia movementCostalgia rib

Root Word: neur/o, denotes the nerves or nervous system

Neruobiology life, study of

Neuritis inflammation

Neuroma tumor, swelling

Neuropathy disease

Neruosis disease condition

Root Word: cephal/o, denotes cranium (head)

Cephalocele hernia

Cephaloplegia paralysis

Cephalometer measure

Cephalic pertaining to

Cephalocaudal tail, pertaining

to

Medical Abbreviations

Letter O Meaning

O2 oxygen

ob or obs obstetrics

od overdose

oint ointment

OJ orange juice

OOB out of bed

opp opposite

OR operating room

Ord orderly

Orth Orthopedics

os mouth

OU each eye

oz ounce