Name ____________________________________________________________ Period ______
SPECIAL SENSES
The Senses
___________________________________ of touch
o Temperature
o Pressure
o Pain
___________________________________
o Smell
o Taste
o Sight
o Hearing
o Equilibrium
The Eye and Vision
___________________________________________________________ are in the eyes
____________________ has over a _______________________________________
_____________________________________________________
o Most of the eye is enclosed in a bony orbit
o A cushion of fat surrounds most of the eye
Accessory Structures of the Eye
______________________
______________________
Meibomian or ________________ glands – modified sebaceous glands of the eyelid
produce an oily secretion to lubricate the eye
_________________________ glands – modified sweat glands between the eyelashes
___________________________________
o Membrane that ________________ the eyelids
o __________________________ to the surface of the eye
o __________________ mucus to ___________________________ the eye
_____________________ apparatus
o Lacrimal __________ –
produces _____________
______________ – located
above the lateral end of each
eye
o Lacrimal canals – _________
lacrimal fluid from ________
into the lacrimal ________ –
medial location
Lacrimal sac – provides __________
of lacrimal fluid towards nasal cavity
____________________________ – empties lacrimal fluid into the _________________
Function of the Lacrimal Apparatus
Properties of __________________________________
o Dilute ______________ solution (tears)
o Contains ___________________ and ___________________, an enzyme that
destroys bacteria
_________________, _____________________, and _____________________ the eye
Empties into the nasal cavity (_____________________!)
Six Extrinsic Eye Muscles
______________________ attach to the outer surface of the eye
Produce __________________________________________
Structure of the Eye
The wall is composed of __________________________________
o ___________________ tunic or _________________– outside layer
o ___________________ tunic or _________________ – middle layer
o ___________________ tunic or _________________– inside layer
The Fibrous Tunic
________________________
o White connective tissue layer
o Seen anteriorly as the “_____________________________________”
_________________________
o __________________________, central anterior portion
o Allows for __________________________________________________
o ___________________________________________________________
o The only human tissue that can be transplanted without fear of rejection
(_________________________________________)
Vascular Tunic or Choroid Layer
_______________________________ nutritive tunic w/ dark pigment
___________________________ prevents light from scattering
Modified interiorly into two structures
o ______________________________ – smooth muscle
Attaches to _________________ by ciliary zonule, a ligament
o __________________ – smooth muscle
Pigmented layer that gives ____________________________
Pupil – rounded __________________________ in the iris
Sensory Tunic (Retina)
Contains ___________________________________ (photoreceptors)
o Rods (_______________)
o Cones (______________)
Signals pass from photoreceptors via a two-neuron chain
o __________________________________
o __________________________________
Signals ________________________ toward the brain through the _________________
Neurons of the Retina and Vision
______________
o Most are found _____________________________ of the _________________
o Allow __________________________ and ________________________ vision
o Perception is all in __________________________________
___________________
o Allow for _____________________________ vision
o Densest in the _____________________ of the retina
o ____________________________ – area of the retina with _________________
– lateral to each blind spot
No ______________________________ cells are at the ____________________, or
blind spot – where the optic nerve leaves the eyeball
Cone Sensitivity
There are ____________ types of cones
Different cones are _______________
to different ______________________
o One blue, another green and the
3rd a range including green and
red (“red cones”)
Color blindness is the result of ______
______________________ type
Lens
_____________________ crystal-like structure
Held in place by a suspensory __________________ attached to the ciliary body
Internal Eye Chamber Fluids
_________________________________
o ___________________ fluid found in chamber between the _________________
o Similar to blood __________________; secreted by a special area of __________
o Helps maintain intraocular _________________
o Provides _______________________ for the lens and cornea
o Reabsorbed into _______________ blood through the scleral venous sinus or
canal of Schlemm
Vitreous humor
o ______________________ substance behind the lens
o Keeps the eye from __________________________
o Lasts a lifetime and is _____________ replaced
Lens Accommodation
Light must be __________ to a
point on the _____________
for optimal vision
The eye is set for ___________
vision (over 20 ft away)
The __________ must change
shape to focus for closer
objects
Images Formed on the Retina
Visual Pathway
_____________________ of
the retina
___________ nerve– bundle of
axons carrying retinal impulses
Optic nerve _____________ at
the optic chiasma
Optic ____________ – contain
fibers from the lateral side of
the eye on the same side and
the medial side of the opposite
eye
Optic tract fibers synapse w/
neurons in the thalamus
______________________
(axons form optic radiation)
________________________
of the occipital lobe
Eye Reflexes
Internal muscles are controlled
by the __________________
nervous system
o Bright light causes
pupils to _______________ through action of radial and ciliary muscles
o Viewing close objects causes accommodation
External _____________________ control eye movement to follow objects
Viewing close objects causes _________________________ (eyes moving medially)
The Ear
Houses two senses
o ______________________
o _____________________________ (balance)
Receptors are mechanoreceptors
Different organs house receptors for each sense
Anatomy of the Ear
The ear is divided into three areas
o ________________ (external) ear
o ________________ ear
o ________________ ear
The External Ear
Involved in ____________________________
Structures of the external ear
o ____________________ (auricle)
o _______________________ auditory canal
The External Auditory Canal
Narrow chamber in the temporal bone
Lined with skin
______________________ (wax) glands are present
Ends at the __________________________________
The Middle Ear or Tympanic Cavity
_________________________ cavity within the temporal bone
o Flanked laterally by eardrum and medially by a bony wall with 2 openings, the
oval window & the inferior, membrane-covered round window
Only involved in the sense of ______________________
Two tubes are associated with the inner ear
o The ___________________ from the auditory canal is _________________ by
the tympanic membrane
o The ________________________ connecting the middle ear with the throat
Allows for _________________ pressure during yawning or swallowing
This tube is otherwise _________________________
Bones of the Tympanic Cavity
Three bones (ossicles) span the cavity
o Malleus (_________________)
o Incus (_________________)
o Stapes (________________)
__________________ from eardrum move the ________________, which moves the
anvil, which moves the stirrup and presses on the oval window of the inner ear
These bones ________________________ to the inner ear
Inner Ear or Bony Labyrinth
Includes sense organs for hearing and ___________________
Filled with _______________________
A maze of bony chambers within the __________________________
o Cochlea
o Vestibule
o Semicircular canals
Chemical Senses – Taste and Smell
Both senses use __________________________
o Stimulated by chemicals in solution
o ____________________ has four types of receptors
o Smell can differentiate a large range of chemicals
Both senses complement each other and respond to many of the same stimuli
Olfaction – The Sense of Smell
Olfactory receptors (neurons with long cilia) are in the
_____________________________
o Chemicals must be _____________________________ for detection and impulse
transmission by the hairs (cilia)
Impulses are transmitted via the olfactory nerve
Interpretation of smells is made in the _________________
Cortex stores “snapshots” of smells & is tied to the limbic system (emotions)
Olfactory Epithelium
The Sense of Taste
_______________________ (10,000+) house the receptor organs
Location of taste buds
o Most are on the tongue
o Soft palate
o Cheeks
The Tongue and Taste
The tongue is covered with projections called papillae
o _________________ papillae – sharp with no taste buds
o ___________________ papillae – rounded with taste buds
o _______________________ papillae – large papillae with taste buds
Taste buds are found on the sides of papillae
Structure of Taste Buds
__________________________ are the receptors
o Have gustatory _______________ (long microvilli)
o Hairs are ______________________ by chemicals dissolved in _____________
Depolarizes the nerve and the impulse is carried to the brain
Impulses are carried to the gustatory complex by several cranial nerves because
____________________________ are found in different areas
o Facial nerve
o Glossopharyngeal nerve
o Vagus nerve
Anatomy of Taste Buds
Taste Sensations
________________ receptors
o Sugars
o Saccharine
o Some amino acids
________________ receptors
o Acids
_________________ receptors
o Alkaloids
____________________ receptors
o Metal ions
Developmental Aspects of the Special Senses
___________________________________ embryonic development
Eyes are _________________________________________
o Developing by the 4th week
o Eyeballs enlarge until age 8 or 9 (lenses throughout life)
o Babies can’t see near at birth (hyperopic)
All special senses are __________________________________