Human and Social Biology: Senses, Eye Anatomy, and Sight Defects

Vocabulary practice flashcards covering sense organs, detailed anatomy of the human eye, photoreceptors, light regulation, accommodation, and common sight defects.

Stimulus

A response to change in an environment detected by specialized sense organs.

Sense organs

Specialized organs adapted to detect specific types of stimuli, including the skin, eyes, tastebuds, nose, and ears.

Receptors

Structures responsible for getting signals which are then transmitted to the sense organs.

Skin

A sense organ that detects touch or changes in temperature.

Tastebuds

Sense organs that detect sweet, salty, sour, savory, and bitter food.

Nose

A sense organ that detects scent and chemicals found in the air.

Ear

A sense organ that detects sound waves to help us hear.

Sclera

The tough, white outer layer that protects the eyeball and does not allow light in.

Conjunctiva

The structure that lubricates the eyes.

Cornea

The part of the eye that refracts and bends light rays as they enter the eye.

Iris

The structure containing circular and radial muscles that controls the size of the pupil and the amount of light entering the eye.

Pupil

The opening that controls the amount of light entering the eye, becoming smaller in bright light and larger in dim light.

Lens

The eye structure that refracts and makes fine adjustments to focus light rays onto the retina.

Ciliary muscles

Muscles that pull onto the lenses to adjust their thickness and focus during accommodation.

Suspensory ligaments

Ligaments that are pulled tight when ciliary muscles relax to make the lens long and thin when focusing on distant objects.

Choroid layer

The middle layer of the eye.

Aqueous humour

The fluid that gives the eye its shape.

Vitreous humour

A thick substance that gives the eye its shape.

Retina

The inner layer containing receptor cells that detect sight and where an image of the object is formed.

Photoreceptors

Light receptor cells in the retina consisting of two types: rods and cones.

Rods

Photoreceptors that function in low light and detect brightness.

Cones

Photoreceptors that function in high light intensity to detect color and fine detail, with three types detecting red, green, or blue wavelengths.

Fovea

The area composed entirely of cones that represents the point of sharpest vision.

Blind spot

The region in the eye with no light receptor cells (no rods or cones).

Optic nerve

The nerve in each eye that sends impulses to the brain.

Accommodation

The process of focusing on distant or near objects; for distant objects, ciliary muscles relax, suspensory ligaments pull tight, and the lens becomes long and thin, bending light less.

Myopia

Short-sightedness, a sight defect corrected using lenses.

Hypermetropia

Long-sightedness, a sight defect corrected using lenses.

Presbyopia

A sight defect also referred to as old sight.

Concave lens

A diverging artificial lens used to correct sight defects.

Convex lens

A converging artificial lens used to correct sight defects.

Glaucoma

A specific condition classified as a sight defect of the eye.

Cataract

A specific condition classified as a sight defect of the eye.

Astigmatism

A specific condition classified as a sight defect of the eye.