Special Senses Structures General Functions

Objective 4 of Special Senses Describe the general function of the structures of the tongue, nasal cavity, eye and ear.

Stratified squamous epithelium on the tongue

The stratified squamous epithelium on the tongue has a dual function of protection and taste.

Papillae

House the taste buds that detect taste and provide tactile feedback, helping with activites like eating, swallowing, and speech.

Taste Buds

They act as chemoreceptors that detect the basic tastes (sweet, sour, salty, bitter, and umami) in food and beverages.

Ganglion cells

Neurons in the retina that process visual information and transmit it to the brain via optic nerve

Bipolar cells

Transmit signals from photoreceptor cells (rods and cones) to ganglion cells

Rods

Photoreceptors, black and white vision, not in fovea, detect absense of light

Cones

photoreceptors, concentrated on central vision, not too functional in low light, numerous in fovea, responsible for color vision and visual acuity

Choroid (pigmented epithelium)

Full of blood vessels that nourish the retina

Sclera

Provides an attachment site for the extraoccular muscles (obliques and rectus)

Ampula

senses motion

Cristae ampularis

Detect rotational movements of the head 

Lacrimal gland

Produce tears, which lubricate and clean the surface of the eye

Inferior and superior lacrimal canals

To drain tears from the surface of the eye into the lacrimal sac

Lacrimal sac

collect tears from the eyes and drain them into the nasal cavity

Nasolacrimal duct

to drain tears from the eye

Superior and inferior eyelids

to protect the eye by acting as a physical barrier against injury and foreign objects, keeping it moist by speading tears, and controlling the amount of light that enters

Lacrimal caruncle

to secrete a whitish, oily substance from its sebaceous and sweat glands to lubricate the eye and contribute to the maintenance of the tear film (eye booger)

Superior, inferior, medial, and lateral rectus muscles

control basic eye movement

Superior and inferior oblique muscles

Provide eye movement (rolling eyes)

Optic nerve

transmits visual information from the retina to the brain

Conjuctiva

to moisten and lubricate the eye while protecting it from irritants and pathogens

Sclera

provide protectin and structural support for the eyeball

Cornea

protect the eye and refract light to help with focusing vision

Ciliary Body

produces aqueous humor

Iris

Controls the size of the pupil

Pupil

Controls the amount of light that enters the eye to ensure clear vision

Lens

Refract or bend light rays to either converge them at a focus or diverge them

Anterior segment- aqueous humor

Fills the anterior chamber between lens and cornea

Posterior segment- vitreous body 

Fills the posterior segment of the eye

Retina

Convert light into electrical signals that are transmitted to the brain, enabling vision

Blind spot (optic disk)

Area through which blood vessels enter and nerve processes exit the eye

Fovea centralis

Area of great visual acuity

Pinna

to collect and funnel sound waves into the ear canal

Ear canal

Transmits sound waves from the outer ear to the eardrum

Tympanic membrane

Transmit sound from outer er to the middle ear by vibrating when sound waves strike it

Malleus

transmit sound vibrations from the eardrum to the incus

Incus

to transmit and amplify sound vibrations from the malleus to the stapes in the middle ear

Stapes

to transmit and amplify sound vibrations from the incus (anvil) to the fluid-filled cochlea in the inner ear

Oval window

transmit and amplify sound vibrations from the middle ear to the fluid-filled inner ear

Round window

to act as a pressure relief for the inner ear fluid, allowing for the proper transmission of sound waves through the cochlea

Auditory tube

equalizes air pressure in the middle ear, drains fluid, and protects the ear from pathogens

Vestibular portion

provide the brain with information about head position and motion to maintain balance, spatial orientation, and clear vision during movement

Cochlear portion

auditory transduction–the process of converting sound vibrations into electrical nerve impulses that the brain can interpret as sound

Whole vestibulocochlear nerve

hearing and balance. transmit special sensory information from the inner ear to the brain

Semicircular ducts

sense rotational head movements, balance

Ampulla

sense rotational head movements

Saccule

detect vertical linear acceleration and head tilts

Utricle

balance, detect linear acceleration and head position

Organ of Corti

to convert sound vibrations into electrical signals that the brain can interpret

Vestibular membrane

to serve as a diffusion barrier in the cochlea of the inner ear

Basilar membrane

to process sound frequencies by physically separating them along its length

Tectorial membrane

to stimulate the hair cells in the inner ear to convert sound waves into electrical signals

Fungiform Papillae

House taste buds

Filiform papillae

Provide texture on the tongue

Circumvallate papillae

House taste buds

Olfactory Bulb

receive and process olfactory information from the nose, acting as the first relay station for smell in the brain

Olfactory Epithelium

to detect smells by containing olfactory sensory neurons that are specialized for this purpose