Sensory Receptors and Anatomy of the Eye

Sensory receptors based on stimulus origin

Sensory receptors based on type of stimulus

Gross and microscopic anatomy of the eye

Interoceptors: Stimulus from inside (interior).
Location: Internal organs (like heart beating)

Proprioceptors: Stimulus from muscle / tendons / ligaments / joins

Exteroceptors: Stimulus from the environment.
Location: Skin, special sense organs (like hearing and sight)

Chemoreceptor: Sensitive to chemicals (smell and taste) and checking chemical levels in blood (pH)

Nociceptor: Sensitive to pain. (Remember Noxious = Danger. Noc = Pain)

Photoreceptor: Sensitive to light

Mechanoreceptor: Sensitive to pressure, touch, vibration, stretch

Thermoreceptor: Sensitive to temperature. There are some receptors for warmth, and some for cold

Baroreceptor: Type of Mechanoreceptor: Sensitive to blood pressure.

Three Tunics (layers) of the eye

Vascular Layer

Inner Layer

Fibrous Layer

Sclera - Outer Layer (white color) of the eye. Made up of Dense Connective Tissue. Protective layer. It is the anchor for muscles, and gives the eye it's shape.

Cornea - Transparent, allows light into the eye and helps focus that light.

Choroid - Vascular and nourishes all other tunics. Also absorbs light and prevents light from scattering. Continuous with the Ciliary body.

Ciliary body - muscle that changes the shape of the lens

Retina - Contains the photoreceptors. Axons from photoreceptors converge to become the optic nerve (in the back of the eye)

Functions of Rods and Cones

Rods - Sensitive to light (shades of light and dark) used mostly in dim light. There are more rods than cones in the eye.

Cones - Sensitive to color. Cones work best in bright light.

Location and Function of the lens and iris

Iris - Posterior to cornea, dilate or constrict to allow more or less light into the eye

Pupil - opening in the iris

Lens - Posterior to the iris, focuses light onto the retina

Location and function of the Optic Disc, Macula Lutea, and Fovea Centralis

Macula Luea - Posterior pole, made up of only cones. This is the sharpest vision.

Fovea Centralis - Center of Macula Lutea

Optic Disc - Axons converge to form optic nerve (canal in the back of the eye). There are no photoreceptors (rods and cones) in the optic disc. This is the "blind spot"

Posterior and Anterior cavities and their humor

Posterior Segment - Filled with VITREOUS humor. Viscous liquid transmits light and supports the retina and lens. It helps maintain pressure and the shape of the eye.

Anterior Segment - Filled with AQEUOUS humor. Aqueous humor is a watery substance that transmits light, nourishes the lens and the cornea, and helps maintain pressure and shape of the eye.