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.
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.
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.
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
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.
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
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
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
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
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