5 Special Senses

8/8/2019 5 Special Senses

http://slidepdf.com/reader/full/5-special-senses 1/19

VisionAuditory SenseEquilibriumOlfactory SenseGustatory Sense



Monitor and detect changes in environment and send thisinformation from the receptors to the brain by way of sensory and afferent neurons. T

he brain interprets information and makes appropriateresponse The senses:

1. Sight

2. Hearing and Balance3. Smell

4. Taste5. Cutaneous senses of touch, pain, pressure, temperature

6. Visceral senses of nausea, hunger, thirst, the need to void anddefecate.

7. The extra-sensory perception



1. Orbital cavity cone-shaped cavityformed by the skull that contains theeyeball Padded with fatty tissue that

protects and cushions the eye.

2. Extrinsic ocular muscles providesupport for and control movement of

the eyeball3. Eyelids movable skin folds that givesprotection from the outsideenvironment Eyelashes helps prevent gross

particles from entering the eye andacts as sensors to cause rapidclosure as a foreign objectapproaches the eye

4. Conjunctiva line each eyelid and

exposed surface of the eyeball that actsas a direct protective covering of theeye surface.

5. Lacrimal apparatus lubricates eye bysecreting tears Drains tears into the nose via two

small holes in the inner corner of theeye.

Tears also acts as antiseptic to keep

the eyeballs free from microbialinfection.



1. Fluid media of the eyea. Aqueous (watery) humor fills anterior and posterior chambers of

anterior cavity of eyeball, nourishes lens and cornea

b. Vitreous (jellylike) humor fills posterior cavity, maintains sphericalshape of the eye



2. Layers of the eyeballa. Outer layer consists of the sclera (posteriorly) tough, fibrous connective tissue that serves as a protective

shield. AKA the whites of the eye

Contains cornea specialized transparent portion that allows light rays to pass through the eye

b. Middle layer a highly vascularized and pigmented area that contains the choroid posteriorly, pupil and irisanteriorly. Iris the colored portion of the eye that controls the size of the opening (pupil) where light passes into the eye.

Iris is a sphincter that contracts (in response to bright light) or relaxes/dilates in dim areas to allow more light to passthrough

c. Inner layer consists of the retina Contains the nerve endings that receives and interprets the rays of the light into images.

Lens located behind the pupil surrounded by ciliary muscles.

Ciliary muscles alters the shape of the lens to allow the incoming light rays to focus on the retina



Retina a delicate membrane of the 3rd layer that continuesposteriorly and joins to the optic nerve.

Contains two types of light receptors called rods and cones.

a. Rods active in dim light and do not perceive color

b. Cones active in bright light and perceives color



Combines changes in the size of the pupil and the lens curvature to make sure

the images converges/meet in the same place on the retina to properly focus



Light raysenters the eye

Passes throughthe conjunctivalmembrane and

cornea

And throughthe aqueoushumor, and

pupil

Thru the 3rd

layer lens andvitreous humor

Focused in theretina andsends an

impulse viaphotoreceptors

Into the opticnerve (CN II)and the brain



The ear responsible for hearing and

maintaining equilibrium

The ear receives sound vibrations usually viathe air and translates them into an

interpretable sound via the 8th cranial nerve.



Outer projections of the earincluding the auditory canal,leading into the tympanicmembrane.

1. Pinna or auricle theprojecting part that collectsthe sound waves into theauditory canal (externalauditory meatus).

2. Auditory canal passagewayof sound from the pinna;

contains ceruminous glandsthat secretes cerumen

3. Tympanic membrane separates the external andmiddle ear; protects thetympanic cavity



The space that contains the ossiclesand the auditory tube

A. Ossicles amplify the sound wavesthe tympanic membrane receivesfrom the external meatus.

1. Malleus/hammer 1st ossicleattached in the tympanic membrane

2. Incus/anvil attached to the hammer

3. Stapes/stirrups connects to the ovalwindow

B. Auditory/Eustachean tubes allowair pressure on the eardrum to beequalized.

Connects the nose and throat to themiddle ear, thus transmitting bothoutside atmospheric pressure (noseand throat) and the middle ear.

Equal pressure allows the ossicles andtympanic membrane to freely vibratewith incoming sound waves.



Oval window memrane is theportal into the inner ear orlabyrinth.

Composed of 3 separate hollow,bony cavities that form a

labrynth and twisting channelscalled bony labyrinth1. Cochlea bony spiral or snail

shaped entrance to the internalear connected to the ovalwindow membranes. Contains fluid called perilymph,

w/c helps to transmit the sound to

the area.2. Vestibule chamber housesthe internal ear

3. Semi-circular canals containsendolymph fluid w/c transmitspositional changes (thru the 8th

CN) that helps maintainbalance.



Sound conduction soundwaves enter the external

canal and vibrate theeardrum

Bone conduction as themiddle ear amplifies the

sound through the vibrationof ossicles

Sensorineural conduction -stapes vibrates and causes agentle pumping vs the oval

window, causing the cochlearfluid to vibrate small hair-likenerves in the Organ of Corti

to the temporal lobe for

interpretation



Also referred to as gustatorysense.

Taste buds taste receptorsin the tongue

Gustatory senses1. Sweet2. Bitter3. Salty4. Sour

5. Umami taste of

glutamates, w/c cannot beduplicated by the other 4sense of taste.

Refinement of food isprimarily dependent on thesense of smell



Arises from thereceptors located in theolfactory region, the

upper part of the nasalcavity.

Closely related to the tothe sense of taste.

Pleasant odors initiate

the secretion of thedigestive enzymes cephalic phase of digestion



Tactile corpuscles small round-bodied touchreceptors located in the skin and esp., numerous inthe fingertips, and tip of the tongue.

Temperature receptors of cold and hot temperature. Adaptation continued sensory stimulation that

causes desensitization of the sensors. Pain receptors primary sense of protection in the

free nerve endings.Most widely distributed sense (skin, muscles, joints, bone, viscera,brain etc)

Types of painSomatic, visceral, referred, phantom limb etc





Conjunctivitis inflammation of the outer membrane of the eyes. Cataract dx w/c is characterized by opacity of the lens. Glaucoma increased IOC pressure w/c interferes with optic nerve

functioning.

Presbyopia age-related farsightednes. Myopia nearsightedness Icteric sclerae yellowish discoloration of the eye caused by liver

dx PERLA (pupils equal, reactive to light and accomodation)

diagnostic tool for neurological assessment

Otitis media infection of the middle ear usually a complicationfrom URTI Menieres dx chronic dx condition that affects the labyrinth and

leads to progressive hearing loss and vertigo. Labyrinthitis inflammation of the inner ear usually caused by

high fever resulting to vertigo.



Documents

5 Special Senses