Sense Organs

Front

Sensory organs Noun

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[sen-suh-ree or-gunz]

Back

Sensory organs

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Organs dedicated to helping us perceive the world through sight, hearing, smell, taste, and touch.

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Example: This image shows the five main sensory organs—the eye, tongue, ear, skin (finger), and nose—which allow us to see, taste, hear, touch, and smell.

Front

Peripheral nervous system (PNS) Noun

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[puh-rif-er-uhl nur-vuhs sis-tuhm]

Back

Peripheral nervous system (PNS)

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The division of the nervous system including sense organs and nerves that connect them to the central nervous system.

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Example: This diagram shows the peripheral nervous system as the network of nerves and ganglia that branch out from the central nervous system (brain and spinal cord).

Front

Central nervous system Noun

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[sen-truhl nur-vuhs sis-tuhm]

Back

Central nervous system

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The part of the nervous system, including the brain, that receives and interprets nerve impulses from sensory nerves.

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Example: This diagram shows the central nervous system (brain and spinal cord) receiving sensory signals from sense organs and sending out commands to the body.

Front

Sensory receptors Noun

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[sen-suh-ree ri-sep-terz]

Back

Sensory receptors

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Specialized cells located within a sense organ that are designed to respond to a particular type of environmental stimulus.

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Example: This diagram shows how specialized receptor cells in the nose detect odor molecules (stimuli) and send signals through nerves to the brain.

Front

Stimulus Noun

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[stim-yuh-luhs]

Back

Stimulus

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A detectable change in the internal or external environment that is capable of being perceived by a sensory receptor.

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Example: Touching a sharp cactus spine is a stimulus that causes a pain response, which is detected by nerve endings in the skin (sense of touch).

Front

Sensory nerves Noun

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[sen-suh-ree nurvz]

Back

Sensory nerves

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Nerves that are responsible for carrying impulses from the body's sensory receptors to the central nervous system.

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Example: This diagram shows a single nerve cell (neuron), the basic building block of sensory nerves, which transmit signals from sense organs to the brain.

Front

Cornea Noun

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[kor-nee-uh]

Back

Cornea

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The transparent outer layer at the front of the eye that protects it and helps to focus incoming light.

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Example: This diagram shows the cornea as the transparent outer layer of the eye that light passes through first, helping to focus it onto the retina.

Front

Pupil Noun

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[pyoo-pil]

Back

Pupil

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The dark, circular opening in the center of the iris that allows light to enter the eye.

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Example: This diagram shows the pupil, the black opening in the center of the iris, which allows light to enter the eye.

Front

Lens Noun

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[lenz]

Back

Lens

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The transparent structure located inside the eye that works to focus light rays directly onto the retina.

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Example: This diagram shows how the lens in the eye, a sense organ, bends light waves to focus an inverted image onto the retina.

Front

Retina Noun

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[ret-n-uh]

Back

Retina

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The light-sensitive layer of tissue at the back of the eyeball that triggers nerve impulses for vision.

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Example: This diagram shows the retina's structure, highlighting the light-detecting cells: rods (for dim light) and cones (for color vision).