SPECIAL SENSES

olfactory receptors, hair cells, mechanoreceptors, taste buds, photoreceptors

sensory Receptors

Eye and Vision

70% of all sensory receptors are in the eyes

Eye and Vision

Each eye has over 1 million never fibers carrying information to the brain

Light Entry

Light enters the eye through the cornea and lens, which helps focus it onto the retina at the back of the eye

Neural Signal Transmission

Once activated by light, the receptors transmit electrical signal to bipolar cells, which then relay the signals to ganglion cells

Photoreceptor activation

The light reaches the photoreceptor cells in the retina, specifically rods and cones

Photoreceptor activation

Rods (red structures) help with vision in low light (black-and-write vision)

Photoreceptor activation

Cones (green, red, and blue structures) help detect color

Signal Processing and Transmission

The ganglion cells collect and process the visual information before sending it to the optic nerve

Optic Nerve Transmission

The processed signals are sent via the optic nerve to the brain, where they are interpreted as visual images

Tarsal glands, Ciliary glands

Eyelashes

Tarsal glands

produce oily secretion (lubricates the eye)

Ciliary glands

secrete lipids (for lubrication)

Conjunctiva

Lines eyelids and eyeball

Conjunctiva

Connects with the transparent cornea

Conjunctiva

Secretes mucus (lubricates and maintains moisture in the eye)

Lacrimal gland

produces lacrimal fluid/tears (cleanse, protect, moisten, and lubricate the eye)

Dilute salt solution

Mucus

Antibodies

Lysozome (enzyme that destroys bacteria)

the lacrimal fluid/ tears contain

Extrinsic eye muscles

Produce gross eye movement

Extrinsic eye muscles

Six muscles attach to the outer surface of the eye

Extrinsic eye muscles

Lateral rectus, medial rectus, superior rectus, inferior rectus, inferior oblique, superior oblique

Tunics

Layers of the eyeball

Tunics

Form the wall of the eyeball

Tunics

Fibrous layer (outside), vascular layer (middle), secondary layer (inside)

Lateral rectus

Moves eye laterally

Lateral rectus

VI (abducens)

Medial rectus

Moves eye medially

Medial rectus

III (oculomotor