1. Touch
Response to a mechanical stimulus. The skin is the largest sensory organ. Sensory receptors detect pressure, pain, heat, cold.

2. Smell
Response to a _chemical_____ stimulus. Sensory receptor cells are bathed in mucus and respond to different chemicals

3. Taste
Response to a _chemical_stimulus. Sensory receptors called _taste buds_ are located on the _tongue. Detect sweet, sour, salty, bitter

4. Vision Response to a _light___ stimulus.
Cornea – Light first passes through the _cornea_____, a transparent, protective covering which begins _focusing___ the light. The light then enters a chamber filled then enters a chamber filled with watery fluid called the _aqueous humor.
_Pupil____ - Hole that light passes through. The size of the pupil is controlled by a ring of muscles known as the _iris___.
_Lens____ - Completes focusing of the light ray. There is also a thick jelly-like substance to help maintain the shape of the chamber known as the _vitreous humor_.
Retina – Nerve tissue at the back of the eyeball that converts light energy to an _electrical impulse_. Made up of two types of cells:
Rods - Cells that detect _shape & movement; are stimulated even in _dim___ light.
Cones - Cells that detect _color; provide a _sharp image; require _bright light for stimulation.
Optic Nerve - Transmits the impulse to the _brain___.
Additional Structures
Sclera - _”White of the eye”; continuation of the _cornea
Choroid - Layer of blood vessels that _nourish the eye.