Special senses

General senses involve touch, temperature, pressure, and pain receptors.
These receptors send signals interpreted by the brain through the nervous system.

Olfactory receptors located in the nasal epithelium detect odors in air.
Signals from these receptors are sent to the olfactory bulb for interpretation in the brain.

Taste buds are found on the tongue, palate, and throat.
Responsible for detecting five sensations: sweet, sour, salty, bitter, and umami.
Taste receptor cells interact with chemical molecules from food and beverages.

The eye is the primary organ for vision.
Light passes through the cornea, lens, and focuses on the retina containing photoreceptor cells (rods and cones).
Signals are transmitted via the optic nerve to the brain for interpretation.

The ear is the organ responsible for hearing.
Sound waves enter the ear canal, vibrate the eardrum, and these vibrations are transmitted through tiny ossicles (malleus, incus, stapes) to the cochlea.
Hair cells in the cochlea convert vibrations into electrical signals sent via the auditory nerve to the brain.

The inner ear is crucial for balance and spatial orientation.
The vestibular system detects changes in head position and movement; signals help maintain balance.

Eyelids, eyelashes, eyebrows, and various glands (Meibomian, tarsal, ciliary) play protective roles and help lubricate the eye.
Conjunctiva is a mucous membrane that protects and lubricates the eye.
Lacrimal apparatus produces and drains tears, which cleanse and protect the eye surface.

Sclera: White connective tissue layer, provides shape and protection and is an anchoring site for muscles.
Cornea: Transparent front layer allowing light to enter; has pain receptors.

Contains blood vessels and pigments; supports the eye and absorbs light to prevent scattering.
Ciliary body controls lens shape; the iris is the colored part of the eye with the pupil allowing light to enter.

Contains photoreceptors (rods for dim light, cones for color vision).
The retina processes light and sends signals through ganglion cells to the optic nerve.

Light enters through the cornea, refracts at the lens, and focuses on the retina.
Photoreceptors in the retina generate signals sent through the optic nerve to the brain for interpretation.

Bony labyrinth and membranous labyrinth contain organs for hearing and balance.
Cochlea: Contains the organ of Corti, where sound is transduced into electrical signals.
Semicircular canals and vestibule are involved in balance and equilibrium.

Sound waves vibrate the eardrum; ossicles amplify this vibration and transmit it to the cochlea.
Organ of Corti converts mechanical vibrations into electrical signals for the brain to interpret.

Static: Maintains balance when stationary (maculae detect head position).
Dynamic: Maintains balance during movement (crista ampullaris responds to head rotation).

Taste buds located on the tongue are stimulated by chemicals from food and beverages.
There are five basic taste sensations: sweet, sour, salty, bitter, and umami.
Taste is closely linked to olfaction, enhancing the perception of flavor.

Tinnitus
- A ringing or buzzing noise in one or both ears that may be constant or intermittent.
- Often associated with hearing loss or exposure to loud noise.
Deafness
- Partial or complete inability to hear.
- Can be conductive (problems with the ear canal, eardrum, or middle ear) or sensorineural (damage to the inner ear or auditory nerve).
Color Blindness
- Difficulty seeing colors or differentiating between them, often affecting reds and greens.
- Caused by genetic factors affecting the photoreceptors in the retina.
Glaucoma
- A group of eye conditions that damage the optic nerve, often linked to high eye pressure.
- Can lead to vision loss if not treated.
Conjunctivitis
- Inflammation of the conjunctiva (the lining of the eye), often resulting in redness, itching, and discharge.
- Can be caused by infections, allergies, or irritants.