| A | B |
|---|
| Semicircular canals | Detect changes in the head’s rate of rotation or angular movement |
| Cupula | A gelatinous mass that hair cells of the semicircular canals project into. This mass is sluggish and experiences pressure from surrounding fluid flow. |
| Compound eye | Consists of many tiny light-detecting units called ommatidia. Best seen in a fly. |
| Single-lens eye | Seen in humans and other mammals |
| Pupil | The small opening in the center of the eye |
| Iris | Analogous to a shutter on a camera; changes the diameter of the pupil |
| Lens | A disclike object that focuses the light on the back of the eye (retina) |
| Retina | The back of the eye; consists of many photoreceptor cells |
| Fovea | The location where the photoreceptor cells are most concentrated; the true center of the eye |
| Sclera | The outer surface of the human eyeball; tough, whitish layer of connective tissue |
| Cornea | At the very front of the eye; technically is “clear” sclera overlying lens, separated by aqueus humor |
| Accommodation | When focusing on an object very close to the eye, the ciliary muscles will contract (pull together) and make the lens more spherical |
| Basilar membrane | The floor of the middle canal to which hair cells are attached |
| Tectorial membrane | The shelf-life projection that hair cells brush against and draw away from when sound is in the environment |
| Cochlea | A fluid-filled channel in the inner ear that houses the organ of Corti, our hearing organ. |
| Organ of corti | The actual hearing organ; composed of upper and lower canals, as well as hair cells attached to a basilar membrane and an overlying, mobile tectorial membrane. |
| Outer ear | Consists of “pinna” (ear), and auditory canal |
| Eardrum | A sheet of tissue that separates the outer ear from the middle ear |
| Middle ear | Houses the hammer, the anvil, and the stirrup |
| Sensory adaptation | The tendency of some sensory receptors to become less sensitive (trigger fewer action potentials) when they are stimulated repeatedly |
| Sensory transduction | When a receptor detects a stimulus and coverts the signal (e.g., a hot flame, a quiet noise) to an electrical signal, creating a change in the membrane potential |
| Receptor potential | In contrast to action potentials, which are all-or-nothing phenomena, these vary; the stronger the stimulus, the greater this potential |
| Sensation | Something the brain “feels” (an action potential) but has not yet interpreted to form a meaningful understanding of (to produce a perception) |
| Perception | The brain’s meaningful interpretation of a sensation (e.g., understanding an AP to be a color, smell, sound, or taste) |
