The Special Senses

Sense of smell. Smell and taste are chemical senses.

Olfactory receptor cells, supporting cells and basal cells

( columnar epithelium) located in the mucous membrane lining the nose. Used for physical support, nourishment and electrical insulation for olfactory receptor cells.

undergo mitosis to replace olfactory receptor cells

produce mucus that is used to dissolve odor molecules so that transduction (conversion into electrical impulses) may occur.

>the cribiform plate> synapse the olfactory bulb> along the olfactory tract> interpreted in the primary olfactory area in the cerebral cortex (temporal lobe)

Binding of an ordorant molecule to an olfactory receptor protein.

Chemical reactions involving cyclic AMP cause depolarization.

Impulses travel to the frontal lobe (orbitofrontal area) for odor identification.

Sense of taste.

Sour, sweet, bitter, salt and umami (meaty/savory)

contain receptors for the sensation of taste. Taste buds are found on the tongue of a young adult and on the soft palate, pharynx and epiglottis.

supporting cells, gustatory receptor cells and basal stem cells

Elevations on the tongue called papillae

Contain tactile receptors but no taste buds. Increase friction to make it easier for the tongue to move food within the mouth. Covers the entire surface of the tongue.

Facial (VII) nerve:carries taste information from the anterior 2/3 of the tongue.

Glossopharyngeal (IX) nerve: carries taste information from the posterior 1/3 of the tongue.

Vagus (X) nerve: carries taste information from taste buds on the epiglottis and in the throat.

uses visible light which is part of the electromagnetic spectrum with wavelengths from about 400 to 700 nm.

The distance between two consecutive peaks of an electromagnetic wave

eyelids, eyelashes, eyebrows, lacrimal (tear-producing) apparatus, extrinsic eye muscles

control eyelid movement

responsible for moving the eyeball itself in all directions

A thin, protective mucous membrane that lines the eyelids and covers the sclera.

A fold of connective tissue that gives form to the eyelids. Contains a row of sebaceous glands (tarsal glands/Meibomian glands) that keep the eyelids form sticking to each other.

Lacrimal glands>lacirmal ducts distribute tears over the surface of the eyeball> lacrimal puncta>lacrimal canaliculi>lacrimal sac>nasolacrimal ducts that carry the tears into the nasal cavity.

Superior rectus, inferior rectus, lateral rectus, medial rectus, superior oblique and inferior oblique.

In bright light the pupil constricts (parasympathetic) and in dim light the pupil dilates (sympathetic).

The point at which the optic nerve exits the eye

The exact center of the retina

Area of highest visual acuity. Found in the center of the macula lutea

Rods: see dim light

Cones: produce color vision

A clear watery liquid that fills the anterior chamber (between the iris and cornea) of the eye.

A transparent, gelatinous substance that fills the posterior cavity (vitreous chamber) of the eye.

Through the cornea> the anterior chamber> the pupil> the posterior chamber> the lens> the vitreous humor> and is projected onto the retina.