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11 Cards in this Set
- Front
- Back
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What is a sense? |
Sense (sensation) is a stimulus: - Information communicated to the CNS about changes in the environment (internal or external) so that the body can react (voluntary or involuntary) with an appropriate response |
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What are the two classes of senses? |
1. General Senses 2. Special Senses |
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About The General Senses |
·Associated with skin,muscles, joints, & other organs -Tactile: touch, pressure, stretch, vibration -Temperature: cold & hear -Pain: information concerning tissue damage or excessive stimulation (e.g. too much heat, pressure, etc.) |
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About The Special Senses |
"Special" Senses because they are limited to the head with specific sense organs innervated by specific cranial nerves: Special Sense- Cranial Nerve- Stimulus- Organ Smell-CN I- Chemical- Nose Vision- CN II- Light- Eye Taste- CN VII & IX- Chemical- Taste Buds Hearing- CN VIII- Sound-Ear Equilibrium-CN VIII- Gravity-Ear |
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Receptors & Sense Organs |
·Receptor: any structure specialized to detect a stimulus;the simplest receptors are dendrites ·Sense Organ: receptors with supporting tissues to enhance or moderate the response to a stimulus |
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What are the special senses? |
1. Smell 2. Sight (vision) 3. Taste 4. Hearing 5. Equilibrium |
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About Smell |
·Smell (olfaction) [olfact=smell] -Olfactory epithelium: The Special Sense Organ of smell; located on the superior nasal concha; functions as a chemoreceptor -Histology of olfactory epithelium: pseudostratisfied ciliated columnar epithelium; basal cells for replacement, supporting cells, and olfactory receptor cells -Olfactory receptor cells: dendrites from olfactory cranial nerve (CN I) fibers; directed through the cribriform plate of the ethmoid to the olfactory bulb which is in turn directs tracts to the temporal lobe of the cerebrum -Olfactory gland: produces mucus to dissolve odor molecules; continuously replenishes the covering of mucus for new odors; to be detected, chemicals must be volatile and water-soluble *Primary Odors ·Seven primary odors have been identified 1. Floral 2. Musky 3. Camphorous 4. Pepperminty 5. Etheral 6.Pungent [stinging] 7. Putrid [rotten] |
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About Sight (vision) |
·Structures of the eye are divided between the eyeball and accessory structures of the eye *Accessory Structures of the Eye: 1. Eyebrows: thickened,hair covered, supraorbit ridges of skin; protect eye from sweat, sunlight, foreign matter,and cushions impacts to the eye & forehead; also instrumental in communication 2. Eyelids (Palpebrae): two (upper & lower) thin, movie folds capable of enclosing the eye; protecting it from injury and desiccation *Associated Structures of the eyelids: -Medial & lateral canthus (commissure): where the eyelids meet -Plica semilunaris [half moon]: vestigial nictitating membrane (third eyelid) in medial can thus -Lacrimal caruncle [small fleshy mass]: upon the medial margin of the plica semilunaris;contains sebaceous & sudoriferous glands; produces "sleep" in eyes -Levator palpebrae superioris muscle: within the larger, more movable upper eyelid; functionally,it retracts the upper eyelid (the lower eyelid lacks such a muscle) -Eyelashes: 2-3 rows of hairs along the free edges of the eyelids;most numerous & longer on upper eyelid;upper & lower eyelashes curve away from each other to prevent interlacing; functionally, eyelashes act as strainers to divert foreign matter from the eye - Tarsal (Meibomian) glands (glands of Zeis): sebaceous glands within the eyelids; ducts open on the free margins of the lids; oily secretion reduces evaporation of the tears; blockage of tarsal glands develops "chalazia" (cysts) - Ciliary glands (glands of Moll): sudoriferous glands associated with the eyelash follicles; lubricates margins of eyelids; infected tarsal glands develop "styes" (abscesses, or "boils") 3. Conjunctiva [joined together]: mucous membrane extending from inner eyelids onto the surface of the "white" of the eye "sclera"; prevents foreign matter from penetrating behind the eye; the mucus produced keeps the eyeball lubricated; the space formed between the inner eyelid and the surface of the eyeball is the conjunctival sac; inflammation of the conjuctiva is conjunctivitis (i.e. "pinkeye") 4. Lacrimal apparatus [tear]: cleans & protects the eyeball with a supply of lacriminal fluid (tears); the passage of tears includes the following structures: -Lacriminal gland & ducts: exocrine gland which produces a dilute saline mucus with antimicrobial properties;tears are secreted into the conjunctival sac of the superior-lateral orbit -Lacrimal punctum [prick point]: small openings on the eyelids in the medial canthus for tear drainage
- Lacrimal canals:small ducts extending from the puncta to the lacrimal sac - Lacrimal sac: common chamber which collects tears from lacrimal canals; situated in the lacrimal fossa -Nasolacrimal duct: duct which passes through the lacrimal foramen to drain the lacrimal sac into the nasal cavity at the level of the inferior meatus 5. Extrinsic eye muscles: six skeletal muscles per eye (two oblique & four rectus) for voluntary movement of the eyeball |
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The Visual Apparatus, Ocular Bulb, or "Eyeball" |
·Structures of the eyeball includes three tunics: -1. Fibrous tunic: avascular, superficial covering; includes two structures: *sclera [hard]: The "white" of the eye; continuous with the dura mater; serves as attachment site for extrinsic eye muscles *Cornea: clear, anterior extension of sclera; suspended from the surface of the iris by the anterior chamber which is filled with aqueous humor -2. Vascular tunic: also known as the uvea [grape]; the middle coat of the eyeball;contains three regions: *choroid [membrane-like]: accounts for all, except the anterior 15%, of the uvea; highly vascular & highly pigmented;forms a dark chamber to absorb light *Ciliary body: apparatus to modify the shape of the lens; smooth muscles (ciliary muscles) act on suspensory ligaments which, in turn, are attached around the perimeter of the lens *Iris: colored portion of the eyeball; continuous with the ciliary body; contains smooth muscle to regulate light into the eye by controlling the diameter of the pupil; it separates the anterior chamber, filled with aqueous humor, from the posterior chamber, filled with vitreous humor -3. Sensory (Nervous) tunic: also known as the retina; the functional portion of the visual sensory organ; contains two types of photoreceptor cells: *Rods: most numerous,active in dim light and for peripheral vision *Cones: active in bright light only for color vision · Other structures of the retina include: -Macula lutea [yellow spot]: area of high concentration of photoreceptor cells; the number of cones increases proportionally from it's periphery toward the center -Fovea centralis: center of the macula lutea; contains cones only for the most detailed vision -Optic disc (blind spot): area of the retina devoid of photoreceptor cells; where optic nerve exits the eye, and also the location of vessels entering & exiting the eye |
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About Taste ( gustation ) |
·Taste receptor cells for taste are chemoreceptors located on the special sense organ, the taste bud (gustatory calyculus) · Cytology of the taste bud includes basal cells for replacement, supporting cells, nd gustatory (taste) cells to stimulate sensory nerve fibers ·Taste buds are located throughout the oral mucosa although they are concentrated on lingual (tongue) papillae * Four classes of lingual papillae: -1. Filiform [thread-like] papillae: most numerous over surface of tongue for added texture to facilitate food manipulation; no taste buds present -2. Fungiform [mushroom-like] papillae: secondly must abundant papillae;forms "dots" on surface of tongue; moderate taste buds -3. Foliate [leaf-like] papillae: confined to the lateral margins of the tongue; includes numerous sensitive taste buds -4. Circumvallate (vallate) papillae: largest , but least numerous; confined to the back of the tongue in a "V" formation *Five Primary Taste Sensations Have Been Identified: 1. Salty: salts usually contain metal ions (Na+, K+, etc.) which are important electrolytes 2.Sweet: produced by sugars which are included in high energy foods 3. Sour: produced by acids (e.g. citric acid in citrus fruits) 4. Bitter: produced by alkaloids (e.g. caffeine, nicotine, etc.); most alkaloids exist as botanical toxins rendering them unpalatable 5. Umami [delicious]: The most recent taste sensation described be the Japanese identifying a "savory" or "meaty" flavor. Produced by free glutamate commonly found in fermented foods (e.g. cheeses), mushrooms, and meats. The sensation is intensified in the presence of sodium;hence, MSG (monosodium glutamate) is popularly used in cooking to enhance flavor *Taste Map (Primary Taste Zones) · Formally showed region differences to taste sensations across the tongue; sweetness at the tip, sourness on the sides, bitterness at the back, and saltiness along the edges (unami was not included during the era of the taste map) ·Recently, the taste map has been discredited; all qualities of taste can be elicited from any region of the tongue containing taste buds |
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About Hearing & Equilibrium: Anatomy of the Ear |
·The ear contains three anatomical divisions: 1. Outer Ear 2. Middle Ear 3. Inner Ear · Structures of the Outer Ear -Auricle (not pinna in humans): directs sound waves into the external auditory canal; includes the following substructures: *Helix: narrow, outer cartilaginous rim *Antihelix: broad, inner cartilaginous rim * Triangular Fossa: superior depression of the antihelix * Concha [shell]: bowl-like space surrounded by the antihelix * Tragus [goat]: fleshy flap projecting posteriorly over the external auditory meatus *Antitragus: tubercle across from the tragus forming the inferior base of the antihelix *Lobule (earlobe): inferior fleshy extension of the two helices, devoid of cartilage, composed of loose connective tissue · External Auditory Canal - Tunnel-like chamber within the temporal bone; channels sound waves to the tympanic membrane (eardrum) -Location of the modified apocrine glands, ceruminous glands; cerumen is produced to trap debris & repel insects · Tympanic membrane (eardrum) - Integumentary membrane closing over the middle ear cavity - Vibrates in response to sound waves; initiates the stimulus for hearing · Structures of the Middle Ear - Also known as the tympanic cavity, the middle ear is an air filled cavity within the petrous portion of the temporal bone; structures within include: *Auditory Ossicles: malleus [hammer] , incus [anvil], & stapes [stirrup]; the ossicles conduct vibrations from the eardrum to the inner ear - Auditory muscles: · The auditory muscles contract in response to sounds of sustained high intensity; thereby, protecting the ossicles by reducing the intensity of mechanical vibrations upon them ·Tensor tympani: inserts on the malleus to create tension on the eardrum during contraction · Stapedius: inserts on the stapes to displace it from the inner ear during contraction · Eustachian (pharyngotympanic) tube - Passage between the middle tympanic cavity and the nasopharynx - Normally flattering & closed; opens during swallowing or yawning -Functionally, it allows for drainage of the tympanic cavity into the nasopharynx, and it equalizes pressure between the tympanic cavity and the external auditory canal · Structures of the inner ear - Osseous Labyrinth [bony maze] *complex hollow spaces within the temporal bone; contains three regions: 1. Cochlea [snail] 2. Vestibule [entrance chamber] 3. Semicircular Canals (superior, posterior, & horizontal) * Two opening of the osseous labyrinth: 1. Oval (vestibular) window: covered by the base of the stapes; where mechanical vibrations enter the inner ear 2. Round (cochlear) window: covered by the secondary tympanic membrane; where vibrations exit the inner ear -Membranous Labyrinth · Collection of membranous ducts & sacs suspended within a fluid, perilymph, inside the chambers of the osseous labyrinth · The hollow spaces within the membranous labyrinth are filled with a second fluid, endolymph · Structures of the membranous labyrinth: 1. Cochlear Duct: within the cochlea; contains the spiral organ of corti for hearing 2. Saccule: within the vestibule, connected to the cochlear duct; receptor cells are located within maculae [spots] for static equilibrium 3. Utricle: within the vestibule,connected to the semicircular ducts; also contains maculae for static equilibrium 4. Semicircular ducts: within the semicircular canals, attached to the utricle; swollen bases, ampullae, contain receptor cells within cristae ampullares for dynamic equilibrium · Innervation of the inner ear: - the vestibulochlear nerve (CN VIII) is formed forms the union of two sensory nerves: 1. Vestibular nerve: from the vestibule for equilibrium 2. Cochlear nerve: from the cochlea for hearing |
