UNITS 10 AND 11

THE NERVOUS SYSTEM AND

SPECIAL SENSES

OBJECTIVES

To describe the structure and function of the nervous system and special senses

To recognize, define, spell and pronounce the terms related to the nervous system and special senses

To recognize, define, pronounce and spell the terms related to the pathology and diagnostic and treatment procedures for the nervous system and special senses.

FUNCTIONS OF THE NERVOUS SYSTEM Coordinates and controls all bodily

functions. When the brain ceases functioning the

organism dies.

DIVISIONS OF THE NERVOUS SYSTEM

• CNS = Central Nervous System• PNS= Peripheral Nervous System• ANS= Autonomic Nervous System

NERVES AND NEURONS

Nerves Neurons

A nerve is one or more bundles of neuron cells (fibers that carry impulses).

Nerves connect the rest of the body to the brain and spinal cord

The neuron is the basic cell of the nervous system. Afferent (sensory) neurons

carry sensory information to the brain and spinal cord

Efferent (motor) neurons carry motor information from the brain and spinal cord to the muscles and glands

Connecting (associative) neurons carry impulses from one neuron to another

THE NEURON

Dendrites are fibers that receive impulses and send them to the cell body

Axons conduct impulses away from the cell body. Terminal end fibers lead the impulse away from the axon and toward

the synapse Synapse is the space between tow neurons or between a neuron

and a receptor organ. Neurotransmitters are chemical messengers that allow the impulse

to jump across the synapse and from neuron to neuron.

THE CENTRAL NERVOUS SYSTEM: BRAIN AND SPINAL CORD

PROTECTION FOR THE CNS Meninges are three layers of membrane that enclose

the brain and spinal cord Dura mater is the thick, tough outer membrane Arachnoid membrane (resembles spider web) is

the second or middle layer Pia mater is the third layer. It is the most delicate

and is located nearest the brain and spinal cord. Cerbrospinal fluid (CSF) is a clear colorless, watery

fluid produced within the ventricles of the brain. If cools, nourishes, and cushions the brain and spinal cord from injury.

The skull and vertebral column are the bony

structures surrounding these organs.

THE CEREBRUM

The cerebrum is the uppermost layer of the brain

It is responsible for the highest level of thought including judgment, memory, association, and critical thinking

There are two hemispheres, right and left. The hemispheres are connected by the corpus callosum

Each hemisphere is divided into 4 lobes. Each lobe is named for the cranial bone that covers it.

THE CEREBRAL LOBES

The frontal lobe controls motor functions and emotions

The parietal lobe is responsible for sensory input

The occipital lobe controls eyesight

The temporal lobe controls the senses of hearing and smell.

THE CEREBELLUM

Cerebellum means “little brain.” it is located at the back of the head below the posterior part of the cerebrum

The cerebellum is responsible for balance and coordinated movement.

THE BRAINSTEM The brainstem connects the cerebrum with

the spinal cord. There are three parts: Midbrain is the most cranial section. It provides

conduction pathways from higher and lower centers.

Pons is the middle section (means bridge). The pons allows the “crossover” of the brain. The right side of the brain controls the left side of the body and the left side of the brain controls the right side of the body.

Medulla Oblongata is the most caudal part of the brainstem. It controls basic life functions including respiration, heart rate and blood pressure.

THE SPINAL CORD Spinal cord is the pathway for impulses

to and from the brain and the body.

It starts at the medulla oblongata and ends at L1 or L2.

PERIPHERAL NERVOUS SYSTEM

Consists of cranial nerves and spinal nervesCranial nerves (12 pairs). They originate

from the undersurface of the brain. They control multiple functions for the head region.

Spinal nerves (31 pairs) are named for the body part they innervate. Spinal nerves originate from the spinal cord and are numbered to correspond with the area of the vertebral column from where they originate (i.e.: C1, T5 or L2)

AUTONOMIC NERVOUS SYSTEM Controls the involuntary actions of the

body There are 2 divisions:

Sympathetic division acts in time of emergency. Gets body ready for “fight or fight.” response. Increases breathing rate, heart rate, and blood

flow to musclesParasympathetic division acts to return the

body to normal after a stressful response. Allows body to maintain homeostasis.

MEDICAL SPECIALTIES RELATED TO NERVOUS SYSTEM Anesthesiologist: physician who specializes in

administering anesthetic agents before and during surgery

Anesthetist: specially trained person (i.e.: nurse) who is trained in administering anesthesia but is not the physician.

Neurologist: physician who specializes in diagnosing and treating diseases and disorders of the nervous system.

Neurosurgeon: physician who specializes in surgery of the nervous system.

Psychiatrist: physician who specializes in diagnosing and treating chemical dependencies, emotional problems an d mental illness. (can prescribe medication)

Psychologist (not M.D.): holds an advanced degree (i.e.: PhD) an specializes in evaluating and treating emotional problems. (cannot prescribe medication)

VOCABULARY TERMSAll terms made from word parts may also appear on

your test Alzheimer’s Disease: group of disorders associated with

degenerative changes in the brain structure that lead to characteristic symptoms including progressive memory loss, impaired cognition and personality changes.

Cognition: mental activities associated with thinking, learning, and memory

Parkinson’s Disease: chronic, slowly progressing degenerative CNS disorder. Signs and symptoms are fine muscle tremors, a masklike facial expression and a shuffling gait.

Tetanus: (aka lockjaw) is acute and potentially fatal bacterial infection of CNS caused by the tetanus bacillus. It can be prevented by vaccination.

Amnesia: disturbance in memory. Can be caused by brain injury, illness, or psychological disturbance.

Concussion: violent shaking up or jarring of the brain Cerebral Contusion: bruising of brain tissue from trauma. Cranial hematoma: collection of blood trapped in the tissues of the

brain. Named for the location of the hematoma.

Conscious: means being alert, awake aware and responding appropriately.

Syncope: (aka fainting) is the brief loss of consciousness caused by lack of oxygen to brain.

Coma: is a profound deep state of unconsciousness marked by the absence of spontaneous eye movements, no response to pain, and no vocalization.

Comatose: refers to a person in a coma. Delirium: potentially reversible condition often

associated with high fever that comes on suddenly. The patient is confused, disoriented and unable to think clearly.

Dementia: slowly progressing decline in mental abilities including memory, thinking, judgment and the ability to pay attention.

Stroke (cerebrovascular accident or CVA) is damage to the brain that occurs when blood flow is disrupted. Can be caused by a blockage in an artery or a hemorrhage. TIA (transient ischemic attack) is the temporary

interruption of blood supply to the brain. The symptoms pass within a few min. However, a TIA may be a warning sign of a stroke.

Epilepsy is a group of neurologic disorders characterized by recurrent seizures Seizure (convulsion): sudden, violent, involuntary

contraction of a group of muscles cause by a disturbance in brain function

Multiple Sclerosis (MS): progressive, autoimmune disorder characterized by scattered patches of demyelination of nerve fibers of the brain and spinal cord. This disrupts the transmission of nerve impulses and causes symptoms including tremors, paralysis and speech disturbances.

Poliomyelitis (polio) viral infection of the gray matter of the spinal cord that may result in paralysis. Can be prevented through immunization

SPECIAL SENSESThere will be no anatomy for this unit, only word parts, and

vocabulary.

Audiologist: specializes in the measurement of hearing function and treats hearing impairment

Ophthalmologist: specializes in diagnosing and treating diseases and disorders of the eye

Optometrist: specializes in measuring the accuracy of vision to determine if glasses or contact lenses are needed.

Otolaryngologist specializes in the care of the ears, nose and throat (may also be called ENT or otorhinolaryngologist.

Cataract: loss of transparency of the lens of the eye. Nystagmus: involuntary, constant, rhythmic movement of

the eyeball. Glaucoma: group of diseases characterized by increased

intraocular pressure resulting in damage to the optic nerve and retinal nerve fibers. Can lead to blindness if untreated

Macular degeneration: gradually progressive condition that results in the loss of central vision by not total blindness.

Astigmatism: condition in which the eye does not focus properly because of uneven curvatures of the cornea

Hyperopia: farsightedness.

Myopia: nearsightedness

Otitis media: inflammation of the middle ear usually associated with an upper respiratory infection

Otitis externa is an inflammation of the outer ear.

Otomycosis (swimmers ear) fungal infection of the external auditory canal.

Vertigo: symptom of several conditions, with a sense of whirling, dizziness and loss of balance

Tinnitus: ringing, buzzing or roaring sound in the ears