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SPECIAL SENSES
General Sense
Chapter 8
__________________ - mixture of general senses
__________
Temperature
Pain
Pressure
Muscles and joints
____________________ - detect stretch, or tension (body’s position)
Five Special Senses
Localized clusters of receptors (taste buds and olfactory epithelium)
__________________
__________________
Complex Sensory Organs (eyes and ears)
___________________
___________________
___________________
The eye and vision
__________________ (tarsal) glands – modified sebaceous glands produce an oily secretion to lubricate the eye
___________glands - modified sweat glands between the eyelashes
___________________ - membrane that lines the eyelids and covers part of the outer surface of the eyeball; secretes
mucous to lubricate eyeball
Conjuctivitis (_____________, its infectious form, is highly contagious)
anatomy of the eye
_______________ gland- produces lacrimal fluid (tears)
____________ - Dilute salt solution containing ___________ and ___________; Protects, moistens, and lubricates
the eye
_________________ ____________ - drains tears from eyes into the nasal cavity
Extrinsic eye muscles p 254
Internal structures of eyeball
Eyeball - hollow sphere composed of three tunics, or coats:
_____________ - outer thick, white connective tissue; clear, central area is the _______________, which allows
light to enter eye (Cornea can be transplanted without fear of rejection.)
______________ - blood-rich nutritive tunic that contains dark pigment to prevent light from scattering inside the
eye; anteriorly, it forms the _____________ ______ (smooth muscle attached to lens) and the iris (pigmented
muscle layer with pupil opening)
_______________ - inner, sensory tunic; contains millions of photoreceptor cells, rods and cones
_______________ - flexible, biconvex crystal-like structure for focusing, separates the eye into fluid-filled chambers
Anterior segment contains ____________ humor - clear watery fluid, provides nutrients for lens and cornea,
reabsorbed into blood through canal of Schlemm
Posterior segment contains ____________ humor - gel-like substance, helps maintain intraocular pressure
Retina
____________ - allow us to see gray tones in dim light and provide for our peripheral vision
____________ - allow us to see color; three varieties - one responds to _______ light, one to _______, and the
third to green and ________ wavelengths; simultaneous impulses are seen as intermediate colors
____________ ________________ - point of sharpest vision, area lateral to the blind spot that contains only
cones
____________ _______ - no photoreceptors at optic disc, where optic nerve leaves the eyeball
__________________ - lack of one or more of the cone types
Lens Accommodation
Light must be focused to a point on the retina for optimal vision
The eye is set for distance vision (over 20 ft away)
The _______ must change shape to focus for closer objects
Images formed on the Retina p 261
Visual Pathway:
_______________ of retina
_____________ Nerve
Optic Nerve crosses at Optic ____________
Optic tracts
_______________
Visual cortex of ______________ lobe
Eye Reflexes
Internal muscles are controlled by the _________________ nervous system
Bright light causes pupils to _______________ through action of radial and ciliary muscles
Viewing close objects causes _______________________
External muscles control eye movement to follow objects
Viewing close objects causes ______________________ (eyes moving medially)
The ear
Houses two senses:
_______________
________________(balance)
Receptors are mechanoreceptors
Different organs house receptors for each sense
anatomy of ear
Divided into three areas:
Outer (external) ear
Middle ear
Inner ear
_______________ ear
Involved in hearing only
Structures:
____________ (auricle)
External auditory canal -narrow chamber extending to eardrum, contains ceruminous (wax) glands
________________ ear (tympanic cavity)
Air-filled cavity within the temporal bone
Only involved in the sense of hearing
The opening from the auditory canal is covered by the _____________ membrane
The auditory tube connecting the middle ear with the ______________
Allows for equalizing pressure during yawning or swallowing
This tube is otherwise collapsed
Bones of the middle ear
Three ossicles (bones):
____________(malleus)
____________ (incus)
_____________ (stapes)
Vibrations from the eardrum move the malleus and transfer sound to the inner ear
_______________ ear or bony labyrinth
Includes sense organs for hearing and balance
Filled with perilymph
A maze of bony chambers within the temporal bone:
_____________
_______________
___________________ _______________
Organs of hearing
__________of__________
Located within the cochlea
Receptors = hair cells on the basilar membrane
Gel-like tectorial membrane is capable of bending hair cells
Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on ___________ lobe
Mechanism of hearing
Vibrations from sound waves move _______________ membrane
_________ cells are bent by the membrane
An action potential starts in the cochlear nerve
Continued stimulation can lead to _______________
Organs of equilibrium
Receptor cells are in two structures:
Vestibule and Semicircular canals
Equilibrium has two functional parts:
____________ equilibrium - which way is up/down
__________________equilibrium - movement in three planes
Static equilibrium
_______________ – receptors in the vestibule
Report on the position of the head
Send information via the vestibular nerve
Anatomy of the maculae Hair cells are embedded in the otolithic membrane
______________ (tiny stones) float in a gel around the hair cells
Movements cause otoliths to bend the hair cells.
Dynamic equilibrium
_________ ______________ – receptors in the semicircular canals, tuft of hair cells
______________ (gelatinous cap) covers the hair cells
Action of angular head movements:
The cupula stimulates the hair cells.
An impulse is sent via the vestibular nerve to the ___________________.
Chemical senses - Taste and Smell
Both senses use chemoreceptors
Stimulated by chemicals in _________________
Taste has four to five types of receptors
Smell can differentiate a large range of chemicals
Both senses complement each other and respond to many of the
same stimuli
_______________ - sense of smell
Olfactory receptors are in the roof of the nasal cavity
Neurons with long cilia
Chemicals must be dissolved in ____________ for
detection
Impulses are transmitted via the olfactory nerve
Interpretation of smells is made in the cerebral cortex of
the temporal lobe
Sense of taste
Taste buds house the receptor organs
Location of taste buds:
Most are on the ______________
_________ _____________
_________________
The tongue is covered with projections called papillae:
____________ papillae – sharp with no taste buds
____________ papillae – rounded with taste buds
________________ papillae – large papillae with taste buds
Taste buds are found on the sides of papillae.
Structure of taste buds
_______________ cells are the receptors
Have _____________ hairs (long microvilli)
Hairs are stimulated by chemicals dissolved in saliva
Impulses are carried to the gustatory complex by several cranial nerves
because taste buds are found in different areas:
Facial nerve
Glossopharyngeal nerve
Vagus nerve
Taste sensation
Major types of taste buds:
_________ receptors (sugar, saccharine, some amino acids)
_________ receptors (acids/hydrogen ions)
_________ receptors (alkaloids)
_________receptors (metal ions in solution)
_________receptors - savory (glutamates)
All receptors can be found on all regions of the tongue. Spicy foods excite ________ receptors in the mouth.
Developmental aspects of special senses
formed early in embryological development
eyes are outgrowths of brain
all special senses are functional at birth
Normal consequences of aging:
_____________ - age-related farsightedness
_____________ - sensorineural deafness due to atrophy of organ of Corti
dulled sense of taste and smell as receptors are replaced more slowly