Sense Organs

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The pathway involves four main steps: 1) Stimulus from environment (light, sound, chemicals, etc.) 2) Reception by specialized receptors in sense organs 3) Conversion to nerve impulses (electrical sig…

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Sensory receptors are specialized cells or structures in sense organs that detect specific types of stimuli from the environment. They convert physical or chemical energy into nerve impulses. Each rec…

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RODS: 125 million in number, contain rhodopsin pigment, function in dim light/night vision, detect light intensity only (no color), distributed throughout retina except fovea. CONES: 7 million in numb…

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Accommodation is the eye's ability to change its focal length to focus on objects at different distances. It involves: 1) Ciliary muscles contract or relax 2) This changes tension in suspensory ligame…

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The blind spot is the area of the retina where the optic nerve exits the eye. It contains no photoreceptors (rods or cones), so no vision occurs here. We don't notice it because: 1) The other eye cove…

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This is called dark adaptation. In bright light, rods are inactive and cones function. When entering darkness: 1) Cones stop functioning (need bright light) 2) Rods need time to regenerate rhodopsin p…

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1) SCLERA (outermost): Thick, tough, fibrous, white layer providing protection. Forms transparent cornea at front. 2) CHOROID (middle): Black layer with blood vessels, prevents internal light reflecti…

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1) Sound waves collected by pinna → 2) Travel through auditory canal → 3) Vibrate tympanum (eardrum) → 4) Vibrations amplified by ear bones (malleus, incus, stapes) → 5) Stapes vibrates oval window → …