Sensory Organs (Special Senses) Flashcards

A complete set of vocabulary flashcards covering the anatomy and physiology of sensory organs, including vision, hearing, balance, taste, and smell, based on lecture notes.

Special Senses

A group of senses consisting of taste, smell, sight (vision), hearing, and balance which use specialized receptor cells to detect stimuli.

Cornea

A thick, transparent layer at the front of the eye that protects the internal structures.

Iris

The colored part of the eye that controls the amount of light entering by adjusting the pupil diameter using radial and circular muscles.

Lens

A transparent structure located behind the iris, supported by suspensory ligaments, that focuses light rays onto the retina.

Ciliary Body

A structure that encircles the lens and contains muscles that control the thickness and shape of the lens.

Conjunctiva

A layer of squamous epithelium that covers the outer surface of the eye.

Retina

The innermost layer of the eye containing photoreceptor cells responsible for capturing light and beginning the process of vision.

Rods

Photoreceptor cells that account for $95\%$ of photoreceptors in dogs and cats; they function in dim light, are not sensitive to color, and provide night vision.

Cones

Photoreceptor cells accounting for $5\%$ of receptors in dogs and cats; they function in bright light and are responsible for color vision.

Optic Nerve (II)

The second cranial nerve that carries nerve impulses generated by photoreceptor cells to the visual cortex of the brain.

Accommodation

The process by which the eye adjusts the thickness of the lens to ensure an external image falls exactly on the retina.

Myopia

A condition also known as short-sightedness where the image falls in front of the retina, making distant objects appear blurry.

Hyperopia

A condition also known as long-sightedness where the image falls behind the retina, often resulting in distant objects being seen more clearly than close ones.

Meibomian Glands

Also known as tarsal glands, these open onto the eyelid edge and produce oily tears to prevent evaporation of the watery tear film.

Lacrimal Gland

The gland responsible for the production of tears.

Nasolacrimal Duct

The pathway through which tears enter the nasal cavity after passing through the lacrimal canaliculi.

Pinna

The visible outer portion of the ear, composed of elastic cartilage and skin, which collects and funnels sound waves.

Tympanic Membrane

Commonly known as the ear drum, this paper-thin boundary vibrates when struck by sound waves and transmits vibrations to the middle ear.

Ossicles

Three small bones in the middle ear ($\text{malleus}$, $\text{incus}$, and $\text{stapes}$) that amplify and transmit sound vibrations to the inner ear.

Eustachian Tube

A tube connecting the middle ear to the pharynx used to equalize air pressure on both sides of the tympanic membrane.

Cochlea

A snail-shell-shaped structure in the inner ear lined with hair cells that convert sound vibrations into electrical signals.

Vestibular System

The part of the inner ear responsible for balance and equilibrium, consisting of three semicircular canals and otolith organs ($\text{utricle}$ and $\text{saccule}$).

Vestibulocochlear Nerve (Cranial Nerve VIII)

The nerve responsible for transmitting auditory and balance signals from the inner ear to the brain.

Taste Buds

Chemoreceptors consisting of gustatory cells and supporting cells that detect chemicals to create the sense of taste.

Glossopharyngeal Nerve (IX) and Facial Nerve (VII)

The cranial nerves responsible for carrying taste information from the taste buds to the brain.

Olfaction

The sense of smell, achieved by olfactory epithelium covering the nasal cavities.

Olfactory Nerve (Cranial Nerve I)

The nerve that transmits electrical signals from olfactory receptors to the olfactory bulbs in the forebrain.

Glaucoma

A condition characterized by increased intraocular pressure resulting from inadequate drainage of aqueous humour.