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The Nervous System. By: Kaylen Bunch & Kenzie Murphy. Major Structures. Central Nervous System (CNS): Brain & Spinal Cord Peripheral Nervous System (PNS): Network of nerves & Neural tissues Major Function: Sends signals threw the brain and spinal cord to the rest of the body. .

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The nervous system

The Nervous System

By: Kaylen Bunch & Kenzie Murphy

Major structures
Major Structures

  • Central Nervous System (CNS):

    • Brain & Spinal Cord

  • Peripheral Nervous System (PNS):

    • Network of nerves & Neural tissues

  • Major Function:

    Sends signals threw the brain and spinal cord to the rest of the body.


  • Specialized conductors of impulses that enable the body to interact with it's internal and external environments.


  • Neuroglia: supporting tissue

  • Axon: long slender projection of a nerve cell that conduct impulses away from the cell body.

  • Dendrites: Are short & unsheathed, & transmit impulses to the cell body.


  • Motor Neurons: Contractions in muscles & secretions from glands & organs.

  • Sensory Neurons: Attached to sensory receptors & transmit impulses to CNS.

  • Interneurons: Mediate impulses between sensory & motor neurons.

Nerve fibers
Nerve Fibers

  • A single elongated process.

  • PNS fibers: Wrapped by sheaths containing Schwann cells, so damage is reversible,

  • CNS fibers: No Schwann cells, so permanent damage.

Nerves a bundle of nerve fibers that connect to various parts of the body
Nerves: a bundle of nerve fibers that connect to various parts of the body

  • Afferent: Conducting to the CNS

  • Efferent: Conducting to muscles, organs, & glands.

  • Mixed: Mixture of afferent and efferent.

Nerve impulse
Nerve Impulse

  • All or None Principle: No transmission occurs until the stimulus reaches a minimum strength then a maximum impulse is produced.

  • Synapse: A specialized knoblike branch ending.

  • Neurotransmitter: chemical agent helper.

Cns central nervous system
CNS: Central Nervous System

  • Brain and Spinal Cord

    • Divided into white and gray matter.

    • Spinal Cord’s gray matter is in a “H” shape.


  • The nervous tissue consists of millions of nerve cells & fibers

  • Male- 1380g. or 3.04lbs.

  • Female- 1250g. or 2.75lbs.

  • Function:

    • Receives information from the body

    • Interprets it

    • Gives a response to it

    • Helps perform vital operations

Brain meninges
Brain (Meninges)

  • 3 membranes that enclose the brain.

  • Meninges support blood vessels and contain cerebrospinal fluid.

  • Pia mater - inner layer

  • Arachnoid – middle layer

  • Dura mater – outer layer


  • Description: Divided by the longitudinal fissure into 2 cerebral hemispheres.

  • Function: Contains nerve centers that govern all sensory and motor activity.

  • They are joined by large fiber tracts that allow information to pass between them.

The nervous system




  • The surface of each hemisphere is arranged in folds creating bulges(convolution) & shallow furrows( sulcus).

  • Cerebral Cortex: The surface of each hemisphere, composed of gray, unmyelinated cell bodies.

    • Divided into lobes to identify certain locations.

Cerebrum lobes
Cerebrum Lobes

  • Frontal: Major motor area, site for personality, & speech.

  • Parietal: Contains centers for sensory input from all parts of the body & is the site for the interpretation of language.

  • Temporal: Contains centers for hearing, smell, & language input.

  • Occipital: Primary sensory area for vision.


  • Occupies a place in the back of the skull, is oval shaped & divided into lobes by deep fissures. Is also connected to every part of the CNS.

  • Function: Coordination of voluntary & involuntary complex patterns of movement & adjusts muscles to automatically maintain posture.


  • Thalamus: Relay center for all sensory & motor impulses being transmitted to the sensory & motor areas.

  • Hypothalamus: Regulates autonomic nervous activity & contains neurosecretions used to control metabolic activities.


  • Contains centers that process visual, auditory, & sensory data & relay information to & from the cerebrum.

  • Midbrain: below cerebrum & above pons.

    • Contains 4 small masses of grey cells that are associated with visual reflexes & sense of hearing.


  • Pons: broad band of white matter

  • Contains fiber tracts linking the cerebellum & medulla to higher cortical areas.

  • Plays a role in somatic & visceral motor control.


  • Medulla Oblongata: Connects the pons & the rest of the brain to the spinal cord.

  • Acts as the cardiac, respiratory, & vasomotor control centers.

  • Controls

    • Breathing

    • Swallowing

    • Coughing

    • Sneezing

  • Vomiting

  • Heartbeat

  • Arterial blood pressure

Spinal cord
Spinal Cord

  • Adult cord is about 44 cm. long.

  • Function:

    • Conduct sensory impulses to the brain

    • Conduct motor impulses from the brain

    • Reflex center for impulses entering & leaving spinal cord without involvement of the brain.

Spinal cord1
Spinal Cord

  • Conus Medullaris: Between 12th thoracic & 1st lumbar vertebra. The cord becomes conically tapered.

  • Filum Terminale: terminal thread of fibrous tissue extends from the conus medullaris to 2nd sacral vertebra.

Spinal cord2
Spinal Cord

  • Cauda Equina: (horses tail) terminal portion that forms the nerve fibers that are the lumbar, sacral, & coccygeal spinal nerves.

Cerebrospinal fluid
Cerebrospinal Fluid

  • Colorless fluid produced by the choroid plexuses within the ventricles of the brain.

  • Circulates through the ventricles, central canal, & subarachnoid space. Is removed by the arachnoid villi.

  • Adult 120 – 150mL.

  • Cushions the brain & spinal cord from shocks that could cause injury.

Pns peripheral nervous system
PNS: Peripheral Nervous System




  • Network of nerves branching throughout the body from the brain & spinal cord.

  • 12 pairs of cranial nerves attach to the brain.

  • 31 pairs of spinal nerves connected to the spinal cord.




Cranial nerves
Cranial Nerves

  • Attached to the brain. Arranged symmetrically, 12 to each side of the brain.

  • Function: Provide sensory input, motor control, or a combination of these functions.

Spinal nerves
Spinal Nerves

  • 31 pairs along the length of the spinal cord & from the vertebral canal.

  • Each nerve is divided into 2 roots.

  • Dorsal/Sensory roots: composed of afferent fibers carrying impulses to the cord

  • Ventral Roots: contain motor fibers carrying efferent impulses to muscles & organs

Spinal nerves1
Spinal Nerves

  • Cervical: 8 pairs

  • Thoracic: 12 pairs

  • Lumbar: 5 pairs

  • Sacral: 5 pairs

  • Coccygeal: 1 pair

Ans autonomic nervous system
ANS: Autonomic Nervous System

  • A part of the PNS.

  • Controls involuntary bodily functions:

    • Sweating

    • Secretion of glands

    • Heart

    • Arterial blood pressure

    • Smooth muscle tissue

Ans autonomic nervous system1
ANS: Autonomic Nervous System

  • Composed of efferent fibers from certain cranial & spinal nerves that are divided into the:

    • Sympathetic Division

    • Parasympathetic Division

  • The 2 divisions counteract each other to keep the body in a state of homeostasis.

Sympathetic division
Sympathetic Division

  • Since sympathetic fibers synapse with cell bodies in the sympathetic ganglia, they produce widespread innervation when activated.

  • This is called the fight-or-flight response.

  • This division also causes the release of epinephrine (adrenaline), causing an adrenaline rush.

Fight or flight response
Fight-or-Flight Response

  • During this a person experiences:

Parasympathetic division
Parasympathetic Division

  • Works to conserve energy and innervate the digestive system.

  • When activated it:

    • Stimulates salivary & digestive gland

    • Decreases metabolic rate

    • Slows heart rate

    • Reduces blood pressure

    • Allows material through intestines & absorption of nutrients by blood

Alzheimer s disease ad
Alzheimer’s Disease (AD)

  • Loss of memory & other cognitive functions.

  • Involves the parts of the brain that control thought, memory,& language.

  • Begins after age 60, and risk goes up with age.

  • Not a normal part of aging.


  • Inflammation of the brain

  • Many types are caused by viral infection

  • Symptoms:

    • Sudden fever

    • Vomiting

    • Stiff neck & back

    • Clumsiness

  • Mild cases have full recovery

  • Severe cases can cause death

  • Acute phase last 1 to 2 weeks


  • Infection of the membranes that surround brain & spinal cord.

  • Symptoms:

    • High fever

    • Vomiting

    • Difficulty waking up

  • Caused by many different viruses & bacteria.

  • Viral cases are 10 days or less.

  • Can be deadly if not treated promptly.


  • Brain disorder involving repeated seizures of any type.

  • Cluster of nerve cells in the brain signal abnormally.

  • Symptoms: Begin during childhood

    • Strange sensations.

    • Muscle spasms.

    • Loss of consciousness.

Epilepsy seizure classification
Epilepsy: Seizure Classification

  • Partial seizure: Electrical disturbances are in the brain near the source.

  • Generalized: No onset that involve both hemispheres of the brain.

  • Unilateral: Electrical discharge in only one hemisphere.

  • Unclassified: Doesn’t fit in other categories.

Multiple sclerosis ms
Multiple Sclerosis (MS)

  • A chronic, debilitating disease that attacks the CNS.

  • Causes the body to send antibodies & white blood cells against proteins in the myelin sheath.

  • Causes inflammation & injury to the sheath.

  • Damage slows muscle coordination, visual sensation, & other nerve signals.

  • Varies in severity.

Multiple sclerosis ms1
Multiple Sclerosis (MS)

  • Symptoms:

    • Paralysis.

    • Uncontrollable spasms.

    • Numbness & tingling.

  • Genetic link to the disease.

  • Estimated 400,000 Americans suffer it.

  • Occurs between ages 20 & 50.

  • No known cure.

Parkinson s disease
Parkinson’s Disease

  • Degeneration of nerve cells in the part of the brain that controls movement and causes a shortage of dopamine.

  • 1st Symptom is tremor of a limb.

  • Symptoms:

    • Inability to move.

    • Stooped posture.

    • Speak in a soft voice.

Parkinson s disease1
Parkinson’s Disease

  • Causes:

    • Depression.

    • Dementia.

    • Sleep disturbances.

  • More common in men than women.

  • Average age of onset is 60.

  • No cure.

Stroke brain attack
Stroke (Brain Attack)

  • Death of brain tissue when it doesn't get enough blood & oxygen.

  • Caused either by bleeding or blood clots in the brain.

  • 3rd leading cause of death in the U.S.

  • Occurs in men more often than women.

The ear
The Ear

  • Site of hearing & equilibrium.

  • External: The appendage on the side of the head.

  • Contains:

    • Auricle (Pinna)

    • External acoustic meatus (Auditory canal)

    • Tympanic membrane (Eardrum)

  • Many glands line the canal & secrete earwax to lubricate & protect the ear.

The ear1
The Ear

  • Middle: A tiny cavity in the temporal bone of the skull.

  • Contains:

    • Ossicles: Malleus, Incus, & Stapes.

  • Lined by mucous membrane.

  • Functions:

    • Transmits sound vibrations.

    • Equalizes external/internal air pressure.

    • Controls potentially damaging or disruptive loud sounds.

The ear2
The Ear

  • Inner: Consists of a membranous labyrinth (mazelike network).

  • Contains:

    • Cochlea.

    • Vestibule.

    • Semicircular canals.

Hearing loss
Hearing Loss

  • Noises over 85 decibels can cause permanent loss.

  • 2 in every 10 teens have lost some of their hearing.

  • As it progresses you will start having difficulty hearing when there is noise in the background.

Things that cause hearing loss
Things that cause Hearing Loss

  • Sensory Overload

  • Old age

  • Undiagnosed tumors or undertreated infections

  • Non-functioning ear canal or bones

  • Damage from drugs, trauma, or pressure

Meniere s disease
Meniere’s Disease

  • Abnormality of the inner ear

  • Symptoms:

    • Vertigo

    • Tinnitus

    • Fluctuating hearing loss

  • Affects only one ear

  • No cure

Otitis media om
Otitis Media (OM)

  • Otitis: inflammation of any part of the ear.

  • OM is the most common type.

  • Begins when viral or bacterial infections of the throat spread to the middle ear.

  • More common in children than adults.

  • 75% of children have at least one episode of OM by their 3rd birthday.

Common signs of om
Common Signs of OM

  • Unusual irritability

  • Difficulty sleeping

  • Tugging at one or both ears

  • Fever

  • Fluid draining from the ear

  • Loss of balance

  • Unresponsive to quiet sounds


  • Sensation of ringing or roaring sounds in both ears.

  • At least 12 million Americans suffer this.

  • Causes:

    • Hearing loss

    • Loud noise

    • Medicine

    • Other health problems


  • No cure.

  • Treatments that give some relief:

    • Hearing aids

    • Maskers

    • Medicine or drug therapy

The eye
The Eye

  • Function: vision & sight

  • Orbit: Cone-shaped cavity in the front of the skull. Holds the eyeball.

  • Muscles of the Eye: 6 short muscles that provide support & rotary movement of the eyeball.

  • Eyelids: Protect the eyeballs from intense light, foreign particles, & impact.

The eye1
The Eye

  • Conjunctiva: A protective covering for the exposed surface of the eyeball

    • Helps keep the eyelid & eyeball moist.

  • Lacrimal Apparatus: Produces, stores,& removes tears that cleanse & lubricate the eye.


  • Function: Organ of vision

  • Sclera: outer white part of the eye.

  • Cornea: Transparent anterior portion of the eyeball.

    • Bends light rays & helps focus them on the retina.

  • Choroid: Pigmented vascular membrane that prevents internal reflection of light.


  • Ciliary Body: A thickened potion of the vascular membrane.

    • Secretes nutrient fluids that nourish the cornea, lens, & surrounding tissue.

  • Iris: colored membrane of the eyeball.

  • Retina: Innermost layer of the eye.

  • Lens: sharpens the focus of light on the retina.


  • Clouding of the eye’s lens.

  • Doesn’t spread from one eye to the other, but can be in both.

  • Symptoms:

    • Cloudy or blurry vision

    • Poor night vision

    • Double or multiple vision

    • Often need for change in eyeglasses

Conjunctivitis pinkeye
Conjunctivitis (Pinkeye)

  • An inflammation of the conjunctiva.

  • The most common & treatable eye infection in children & adults.

  • Caused By:virus, bacteria, irritating substances (pool chlorine), allergens, or STD’s.

  • Bolded are the ones that can be spread easily from person to person.

Conjunctivitis pinkeye1
Conjunctivitis (Pinkeye)

  • Symptoms:

    • Redness in the white of the eye

    • Increased amount of tears

    • Itchy & burning eyes

    • Blurred vision

    • Yellow, green, or white discharge from the eyes.


  • A group of eye diseases.

  • Categories: closed-angle(acute), open-angle(chronic), & congenital glaucoma.

  • Occurs when the aqueous humor is blocked & drains too slowly from the anterior chamber.

  • Causing a buildup of intraocular pressure.

  • If diagnosed early, blindness can be prevented.

Factors that predispose you to glaucoma
Factors that predispose you to glaucoma

  • Age of 60 years or more

  • African ancestry

  • Previous eye injury

  • Use of steroid medication

  • Diabetes

Macular degeneration
Macular Degeneration

  • Incurable eye disease

  • Affects more than 10 million Americans.

  • Leading cause of blindness.

  • Caused by: deterioration of the central portion of the retina.

  • Dry: Formation of yellow deposits under the macula.

    • Causing thinning & drying out of the macula.

    • 90% of cases.

    • No known treatment or cure.

Macular degeneration1
Macular Degeneration

  • Wet: Abnormal blood vessels grow under the retina & macula.

    • Vessels bleed or leak fluid, causing the macula to lift up.

    • 10% of cases.

    • To save vision, laser surgery needs to be done immediately


  • Dry:

    • Printed words appear blurry

    • Colors that seem washed out or dull

    • Haziness of overall vision that increases

    • Profound drop in central vision

  • Wet:

    • Visual distortions (straight lines appear wavy)

    • Decreased central vision

    • Central blurry spot

Color blindness
Color Blindness

  • The inability to see certain colors in the usual way.

  • Occurs when there is a problem with the color-sensing pigments in the eye.

  • If just one pigment is missing, you may have trouble seeing the difference in red & green.

  • Most severe form is achromatopsia.

    • Patient can’t see any color, only shades of gray.

Color blindness1
Color Blindness

  • Most is caused by a genetic problem.

  • 1 in 10 men have a form of color blindness.

  • Very few women are color blind.

  • A parent might notice signs of color blindness, when the child is learning their colors.


  • Rice, J. (2008). Medical terminology: A word building approach. (6 ed.). Upper Saddle River, NJ: Pearson Education, Inc.

  • Miller, K., & Levine, J. (2002). Prentice hall biology. Upper Saddle River, NJ: Pearson Education, Inc.