Nervous System Notes p. 1
Neuron- a nerve cell!!
Dendrite-carry messages to the cell body!!- Each neuron can have more than one dendrite!!
Synapse – space between the axon of one neuron and the dendrite of another!!!
Axon- the single long arm of the neuron!!each neuron has only one!!
Myelin sheath (neurilemma)~covers the neuron
Ventricles-four fluid filled cavities in the brain that contain cerebrospinal fluid!!!

Nervous System Notes p. 2
Cranial nerves-there are 12 pairs of cranial nerves!!!
(see: On Old Olympus Towering Tops A Fin and German
Viewed Some Hobs)
Spinal cord-EXTENDS TO THE 2 ND Lumbar Vertebrae!!!
Analyze the function of the nervous system.
Neuron function – transmit message from one cell to the next
Dendrites carry impulse to the cell body
Axons carry impulse away from cell body
Neurilemma (myelin sheath) a. Covering that speeds up nerve impulse along axon b. Fatty substance that protects axon
Neurotransmitter – chemicals that carry an impulse across the synapse
~ Nerve impulse – A stimulus creates an impulse!!!
The impulse travels into the neuron on the dendrite(s) and out on the axon. At the end of the axon, a neurotransmitter is released that carries the impulse across the synapse, to the next dendrite.
Nervous tissue
1. Sensory neurons (afferent) – carry impulses from skin and sense organs to spinal cord and brain
2. Motor neurons (efferent) – carry messages from brain and spinal cord to muscles and glands
3. Associative neurons (interneurons) – carry impulses from sensory neurons to motor neurons
Central nervous system- contains the brain and spinal cord!!!
Brain a. Brain tissue will die
without oxygen b. Meninges-the tough, fluid-containing membrane that surrounds the brain and spinal cord!!!
i. Dura mater – tough, dense fibrous connective tissue ii. Pia mater – covers brains surface- it is the innermost layer of the
Meninges!!
iii. Arachnoid – middle layer iv. Subdural space – between arachnoid and dura mater v. Subarachnoid space – between arachnoid and pia mater, filled with cerebrospinal fluid, acts as liquid shock absorber and source of nutrients for brain.
Ventricles – 4 cavities
~Cerebrospinal fluid fills ventricles and acts as shock absorber!!!
Blood-brain barrier – prevents substances (like drugs) from penetrating brain tissue, but also makes infections like meningitis difficult to cure
~ Choroid plexus – blood vessels that make cerebrospinal fluid!!!

Nervous System Notes p. 3
~ Cerebrum ~ This is the largest part of the brain that is responsible for conscious thought, judgment, memory, reasoning, and will power!!!
-The shallow grooves on the surface of the cerebrum are called Sulci!! Separates the cerebral convolutions
Diencephalon - is made up of the Thalamus and Hypothalamus (9 functions of the hypothalamus!!)
1. ANS control
2. Cardiovascular control
3. Temperature control
4. Appetite control!!!!!
5. Water balance
6. Manufacture of oxytocin
7. Emotional state
8. Sleep control
9. Gastrointestinal control f. Cerebellum-responsible for producing smooth coordinated movements and maintaining body posture!!!
i. Maintenance of balance ii. Maintenance of muscle tone iii. Control of muscle movements
The Pons, Midbrain, and the Medulla are part of the Brain Stem!!!! a. Pons – Controls respiration (in the brain stem!!) b. Midbrain – vision and hearing c. Medulla oblongata – impulses from the medulla control heart rate, blood pressure, and respiration!!!
Autonomic nervous system – regulates visceral organs, not subject to conscious control (like the beating of the heart!!!)
1. Sympathetic system a. Fight or flight – when the body perceives danger, SNS sends message to adrenal medulla to secrete adrenaline and heartbeat increases!!!!
2. Parasympathetic system – counters SNS, decreases heart rate
3. Reflex – unconscious and voluntary!!
a.
b.
Stimulus
Examples: like when you are at the Dr. and they stimulate the Patellar Tendon (Knee) it results in a muscle contraction that is called a Reflex!!!

No.
Nervous System Notes p. 4
Name Receptor Sensory Pathway Effector
I Olfactory Olfactory epithelium
II Optic Retina directly to temporal lobe smell through thalamus to occipital lobe
vision
III Oculomotor eyeball muscle proprioreception
IV Troclear eyeball muscle proprioreception thalamus to midbrain thalamus to midbrain
Eyelid and eyeball muscles, lens
(focusing), pupil (constriction) eyeball muscle
V Trigeminal
VI Abducens
Chewing muscles proprioreception, cutaneous touch and pain receptors for face, jaw and teeth eyeball muscle proprioreception
Thalamus to pons, then to somatosensory area.
Thalamus to midbrain chewing muscles eyeball muscle
VII Facial
VIII Acoustic or Auditory
(Vestibulocochlear)
IX Glossopharyngeal
X Vagus
Facial muscle proprioreception, tongue taste receptors
Hearing and equilibrium organs arterial chemoreceptors and baroreceptors, pharangeal taste receptors, pressure/pain receptors in thoracic and abdominal organs thalamus to pons then somatosensory area and/or to gustatory area
(taste) facial expression muscles, saliva and tear glands thalamus to pons then totemporal lobe
hearing arterial chemoreceptors and baroreceptors, tongue taste receptors, tongue muscle proprioreception thalamus to medulla/pons thalamus to medulla/pons saliva glands, tongue muscles
(swallowing),
(aids in regulation of breathing and
BP)
Swallowing and speaking muscles, smooth muscle and secretory glands in GI tract, Heart muscle, (aids in regulation of breathing, BP and slows
HR)
XI Spinal Accessory
XII Hypoglossal
Neck and shoulder muscle proprioreceptors
Swallowing and speaking muscle proprioreceptors thalamus to medulla thalamus to medulla, swallowing muscles, head and neck muscles
Swallowing and speaking muscles

Nervous System Notes p. 5
COMMON NERVOUS SYSTEM DISORDERS
A . Disorders of the CNS
1.
Meningitis a.
Inflammation of the lining of the brain and spinal cord b.
May be bacterial or viral c.
Symptoms – headache, fever, stiff neck d.
In severe form, may lead to paralysis, coma and death e.
Diagnosis – lumbar puncture f.
If bacterial, treat with antibiotics
2.
Encephalitis-mostly from a viral brain infection a.
Inflammation of the brain b.
Viral or chemical (chemical can be from drugs or withdrawal)!! c.
Symptoms – fever, lethargy, extreme weakness, visual disturbances
3.
Epilepsy a.
Seizure disorder of the brain, characterized by recurring and excessive electrical discharge from neurons!!!! b.
Cause – uncertain c.
Grand mal seizure – severe, convulsive seizure d.
Petit mal seizure – milder, seems to be staring or daydreaming!!
4.
Cerebral palsy a.
Disturbance in voluntary muscular action due to brain damage!!! b.
May be due to birth injury or abnormal brain development c.
Spastic quadriplegia – spastic paralysis in all four limbs d.
Symptoms – head rolling, grimacing, difficult speech and swallowing e.
No impairment of intellect
5.
Poliomyelitis (Polio) a.
Disease of nerve pathways of spinal cord causing paralysis b.
Almost eliminated in USA by vaccine given in childhood!!!
6.
Hydrocephalus a.
Increase of cerebrospinal fluid in the brain, usually from a blockage b.
Symptoms – enlargement of head, usually noticed at birth c.
Rx (treatment) – bypass or shunt to relieve pressure- this is done through a surgical procedure!!
7.
Parkinson’s disease a.
Symptoms – tremors, shuffling gait, pill-rolling and muscular rigidity b.
Cause – decrease in neurotransmitter dopamine c.
Rx – L-dopa and other drugs to treat symptoms
8.
Multiple sclerosis a.
Chronic inflammatory disease of the CNS b.
Immune cells attack myelin sheath of axon, leaving scar tissue c.
Nerve impulses blocked d.
Cause – unknown e.
Symptoms – weakness of extremities, numbness, double vision, nystagmus, speech problems, loss of coordination, possible paralysis!!!! f.
Usually strikes young adult women age 20 - 40
9.
Dementia a.
Loss of 2 areas of complex behavior, such as language, memory, visual or spacial abilities, or judgment!! b.
Interferes with a person’s daily life c.
Usually can’t remember family members!!
10.
Alzheimer’s disease a.
Progressive disease, begins with problems remembering your surroundings, confusion!!!! b.
Nerve endings in brain degenerate and block signals that pass between nerve cells c.
The cause of Alzheimer’s is unknown!! d.
First stage (2-4 years) confusion, short-term memory loss, anxiety, poor judgment!!! e.
2 nd stage (2-10 years) increase memory loss, difficulty recognizing people, motor problems, logic problems, loss of social skills

Nervous System Notes p. 6 f.
3 rd stage (1-3 years) inability to recognize oneself, weight loss, seizures, mood swings and aphasia
11.
CVA-Cerebral vascular accident- (stroke) a.
Interruption of blood and oxygen to brain b.
Tissue death c.
Third leading cause of death in U.S. d.
Risk factors – smoking, hypertension, heart disease, family history e.
Cause – 90% blood clots, 10% ruptured blood vessels in the brain!!!
Symptoms – hemiplegia (half side of the body is paralyzed)!!
, sudden severe headache, dizziness, loss of vision in one eye, aphasia, dysphasia, coma, possible death
B. Disorders of the PNS (peripheral nervous system)
1.
Bell’s palsy a.
7 th cranial nerve involved b.
One side of the face droops (eye does not close properly, mouth droops, numbness on effected side of face !!!!) c.
Cause – unknown d.
Can happen in pregnancy as well!! e.
Symptoms disappear in a few weeks
2.
Neuritis a.
Inflammation of nerve or nerve trunk!!! b.
Symptoms – severe pain, loss of sensation, muscular atrophy, weakness, and paresthesia (tingling, burning and crawling of skin)
C.
Diagnostic tests
1.
Lumbar puncture (spinal tap) removal and analysis of cerebrospinal fluiddone often in the pediatric population especially if they have a high fever!!!
2.
EEG (electroencephalogram) recording of electrical activity of brain!!!
3.
CAT scan (computerized axial tomography) produces cross sectional images
4.
MRI (magnetic resonance imaging) uses a magnetic field along with radio frequency to produce cross-section images of the body. Patient inserted into chamber built within a huge magnet !!!!
D.
Paralysis – loss of power of motion or sensation
E.
Hemiplegia – paralysis on one side of the body
F.
Quadriplegia – paralysis of all four extremities

Nervous System Notes p. 7
Sensory System Notes
Explain the structure of the eye.
Eye -1” in diameter/ Protected by orbital cavity , eyebrows, eyelashes, eyelids
-Lacrimal glands – tears empty into nasal cavity (when we cry, tears flow across the eye into the lacrimal duct, which drains into the nasal cavity)/ Conjunctiva – thin membrane lines eyelids
-Wall of eye made up of three coats-the sclera, the choroid and the retina
-Use of Ophthalmoscope to view the eye!! And the Ophthalmologist is the Dr. working with the eye!!
A.
Sclera
1.
Outer layer
2.
White of the eye
3.
Tough coating, helps maintain shape of eye
4.
Muscles responsible for moving eye attached to sclera = extrinsic muscles
B.
Cornea
1.
Front of sclera (clear part) no blood vessels
2.
Transparent so light rays can pass through
C.
Choroid coat
1.
Middle layer, contains blood vessels
2.
Opening in front is pupil-
3.
Iris - Colored, muscular layer surrounding pupil is
4.
Intrinsic muscles – change size of iris to control amount of light entering through pupil
D.
Lens
1.
Crystalline structure located behind iris and pupil—focuses light rays on the retina
2.
Elastic, disc-shaped, biconvex
3.
The LENS is situated between the anterior and posterior chambersdirectly behind the pupil
E.
Anterior Chamber – filled with aqueous humor (think anterior begins with A and aqueous begins with A)
F.
Posterior Chamber – filled with vitreous humor (which maintains eye shape and refracts light rays!!!)
G.
Retina
1.
Innermost layer
2.
Light rays focus image on retina
3.
Image travels to the cerebral cortex via optic nerve
4.
Rods – sensitive to dim light
5.
Cones – sensitive to bright light and color
6.
Rods and Cones-visual receptors of the retina
7.
Optic disc – on retina, known as blind spot, nerve fibers that form optic nerve
8.

Nervous System Notes p. 8
Analyze the function of the eye.
A.
Eye
1.
Protected by orbit, eyebrows, eyelashes, eyelids
2.
Lacrimal glands – production of tears - empty into nasal cavity and clean the eyes
3.
Conjunctiva – secretes mucous to lubricate eyes-lines the eyelid
B.
Sclera
1.
Tough coating, helps maintain shape of eye
2.
Extrinsic muscles - responsible for moving eye attached to sclera
C.
Cornea - Transparent so light rays can pass through-clear structure of the eye called the “window of the eye”
D.
Choroid coat
1.
Middle layer, contains blood vessels
2.
Intrinsic muscles – change size of iris to control amount of light entering through pupil
3.
Pupil constricts – gets smaller – in bright light
4.
Pupil dilates – gets larger – in dark light
5.
Pupil is really a hole(the black center)
E.
Lens
1.
Where light rays are refracted
2.
The lens has the function of ACCOMODATION – change in the shape of the lens to allow for near and distant vision
F.
Retina
1.
Light rays focus image on retina
2.
Image travels to the cerebral cortex via optic nerve
3.
Rods – sensitive to dim light
4.
Cones – sensitive to bright light and color
5.
Both the RODS and the CONES are the visual receptors in the retina!!
6.
Optic disc – on retina!!, known as blind spot, where nerve fibers that form the optic nerve

Nervous System Notes p. 9
Explain the structure and function of the ear, nose, and tongue.
Outer ear -Pinna (auricle)-this is the outer part of the ear!!/Visible ear/Collects sound waves/External auditory canal
– ear canal/ Cerumen – ear wax, protects the ear /Tympanic membrane – Ear Drum , separates outer and middle ear
Middle earCavity in temporal bone
-Connects with pharynx by Eustachian tube(this is the tube that connects the middle ear cavity and the throat) - which equalizes pressure in the middle ear with outside atmosphere
- Bones - transmit sound waves from ear drum to inner ear/Malleus (hammer)/Incus (anvil)/Stapes (stirrup)
Inner ear
-Cochlea - spiral shaped organ of hearing , contains a membranous tube, the cochlear duct – which is filled with fluid that vibrates when sound waves are transmitted by the stapes
-Organ of Corti – delicate hairlike cells that pick up vibrations of fluid and transmit them as a sensory impulse along the auditory nerve to the brain( The organ of Corti is located within the Cochlea!!)
-Semicircular canals – three structures in inner ear that contain liquid set in motion by head and body movements
-Impulses sent to cerebellum to help maintain body balance (equilibrium)
Pathway of hearing – ear to external auditory canal to tympanic membrane to ossicles (malleus, incus and stapes) to cochlea to auditory nerve to brain
Nose -Smell accounts for 90% of taste/Tissue in the nose, olfactory epithelium, contains specialized nerve cell receptors/Those receptors stimulate the olfactory nerve to the brain
Tongue -Mass of muscle tissue/Bumps on surface are papillae, they contain taste buds/Receptors in taste buds send stimuli through 3 cranial nerves to cerebral cortex
Discuss characteristics and treatment of common sensory disorders.
A. Disorders of the eye
1. Conjunctivitis (Pink eye) a. Inflammation of conjunctival membranes in front of eye b. Redness, pain, swelling and discharge c. Highly contagious-can catch by using the same towels, touching the infected eye and then touching your eye, sharing eye makeup d. Rx – antibiotic eye drops
2. Glaucoma a. Excessive intraocular pressure causing destruction of the retina and atrophy of the optic nerve b. Caused by the overproduction of aqueous humor, lack of drainage, or aging c. Symptoms – develop gradually, mild aching, loss of peripheral vision, halo around light d. Tonometer – measures intraocular pressure e. Rx(treatment) – drugs or laser surgery
3. Cataracts a. Lens of eye gradually becomes cloudy b. Frequently occurs in people over 70 c. Causes painful, gradual blurring and loss of vision

Nervous System Notes p. 10 d. Rx – surgical removal of the lens
4. Sty (Hordeolum) a. Abscess at the base of an eyelash in sebaceous gland b, Symptoms – red, painful, swollen c. Rx – warm, wet compresses
5. Eye injury - Glass or fragment in eye – cover eye and seek medical help, do not remove the object
6. Color blindness a. Cones affected b. Genetic disorder that is carried by female and transmitted to males
B. Vision defects
1. Presbyopia a. Lens loses elasticity, can’t focus on close or distant objects b. Usually after age 40 c. Rx – bifocals
2. Hyperopia a. Farsighted b. Focal point beyond retina, eyeball too short c. Convex lenses help
3. Myopia a. Nearsighted-can’t see far away-can wear glasses or contacts to correct b. Eyeball too long
4. Astigmatism a.. Irregular curvature of the cornea or lens(the front of the eye is uneven), causing blurred vision or eye strain b. Rx – corrective lenses
5. Diplopia – double vision
6. Strabismus (cross-eyed) a. Eye muscles to not coordinate their actions b. Usually in children c. Rx – eye exercises or surgery
7. Ophthalmoscope – instrument for viewing inside the eye
8. Snellen eye chart – chart that uses letters or symbols in calibrated heights to check for vision defects
C. Disorders of the ear
1. Hearing loss a. Hearing is fragile, loud noise over period of time can cause hearing loss b. Symptoms – tinnitus (ringing in ears) and difficulty understanding what people are saying
2. Otitis Media a. Infection of middle ear b. Often complication of common cold in children c. Treatment – antibiotics d. Myringotomy – tubes inserted through tympanic membrane to relieve pressure
3. Otosclerosis a. Chronic, progressive middle ear disorder b. Stapes becomes spongy and then hardens, becoming fixed and immobile c. Rx – stapedectomy and total replacement of stapes
4. Tinnitus – ringing of ears from impacted wax, Otitis media, loud noise, etc.
5. Types of hearing loss a. Conductive – sounds prevented from reaching inner ear b. Sensorineural – problem with inner ear and auditory nerve
Disorders of the nose
Rhinitis -Inflammation of lining of nose with congestion, drainage/Cause – allergies, drugs, infection, odors, etc.
Treatment – eliminate cause, antihistamine

Nervous System Notes p. 11
Semicircular
Canals = 3 parts
COCHLEA
Pupil
(HOLE)
IRIS = colored part of the eye
Extrinsic Eye Muscles
SCLERA = white of the eye
CORNEA