Transcript The Nervous System

 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.
A
single elongated process.
 PNS fibers: Wrapped by
sheaths containing Schwann
cells, so damage is reversible,
 CNS fibers: No Schwann cells,
so permanent damage.
 Afferent:
Conducting to the CNS
 Efferent: Conducting to muscles,
organs, & glands.
 Mixed: Mixture of afferent and
efferent.
 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.

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
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.
Left
Right
 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.
 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.
Cerebellum
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
 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.
 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.
 Cauda
Equina: (horses tail)
terminal portion that forms the
nerve fibers that are the lumbar,
sacral, & coccygeal spinal nerves.
 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.
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.

Central
Nervous
System
Peripheral
Nervous
System
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.

Cranial Nerve
Input/ Impulse
Function/ Control of…
1. Olfactory Nerve
Sensory input
Provides sense of
smell
2. Optic Nerve
Sensory input
Provides vision.
3. Oculomotor Nerve
Motor impulses
Provides impulses to 4
of the 6 external
muscles of the eye &
to the muscle that
raises the eyelid.
4. Trochlear Nerve
Motor impulses
Controls the superior
oblique muscle of the
eyeball.
5. Trigeminal Nerve
Both
Sensory from face,
nose, mouth, &
forehead. Motor to
muscles of the jaw.
6. Abducens Nerve
Motor impulses
Controls the lateral
rectus muscle of the
eyeball.
Cranial Nerve
Input/ Impulse
Function/ Control of…
7. Facial Nerve
Both
Controls muscles of
the face & scalp,
lacrimal glands of the
eyes & the
submandibular &
sublingual salivary
glands, and 2/3 of the
tongue for sense of
taste.
8. Vestibulocochlear
Nerve
Sensory input
Provides for hearing &
equilibrium.
9. Glossopharyngeal
Nerve
Both
Provides general
sense of taste;
regulates swallowing;
controls secretion of
saliva.
Cranial Nerve
Input/ Impulse
Function/ Control
of…
10. Vagus Nerve
Both
Controls muscles of
the pharynx, larynx,
thoracic, &
abdominal organs.
11. Accessory Nerve Motor impulses
Controls the
trapezius &
sternocleidomastoid
muscles; for
movement of the
head & shoulders.
12.Hypoglossal
Nerve
Control of the
muscles of the
tongue.
Motor impulses
 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
Cervical: 8 pairs
 Thoracic: 12 pairs
 Lumbar: 5 pairs
 Sacral: 5 pairs
 Coccygeal: 1 pair

A
part of the PNS.
 Controls involuntary bodily functions:
› Sweating
› Secretion of glands
› Heart
› Arterial blood pressure
› Smooth muscle tissue
 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.
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.


During this a person experiences:
Increased
Decreased
Alertness
Digestive Function
Metabolic Rate
Urinary Function
Respiration
Blood Pressure
Heart Rate
Warming of the body that activates the
sweat glands
 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
 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.
Mild
Moderate
Severe
Loses recent
memory
Mixes identity of
people
Doesn’t
recognize family
Loses judgment
about money
Repeats things
Speaks in
gibberish
Confused about
location of
familiar places
Irritable, anger
when frustrated
Behaves
inappropriately;
hitting, biting
Restlessness,
anxiety,
wandering
Needs total
assistance
Refuses to eat,
forgets to
swallow
 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.
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.






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.

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.

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.

Causes:
› Depression.
› Dementia.
› Sleep disturbances.
More common in men than women.
 Average age of onset is 60.
 No cure.

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.

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.
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.
Inner: Consists of a membranous
labyrinth (mazelike network).
 Contains:

› Cochlea.
› Vestibule.
› Semicircular canals.
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.

Sensory Overload
 Old age
 Undiagnosed tumors or undertreated
infections
 Non-functioning ear canal or bones
 Damage from drugs, trauma, or pressure

Abnormality of the inner ear
 Symptoms:

› Vertigo
› Tinnitus
› Fluctuating hearing loss
Affects only one ear
 No cure

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.

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
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.


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
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.


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), openangle(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.

Age of 60 years or more
 African ancestry
 Previous eye injury
 Use of steroid medication
 Diabetes

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.

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
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.
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.

http://www.youtube.com/watch?v=ivk_i
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