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 __________________________________