Module 6 Sensation - Vision, Hearing, Balance, Taste, Smell, Touch

Flashcards covering sensation topics from Vision, Audition, Vestibular, Taste, Smell, and Touch as presented in the lecture notes.

What is transduction in sensation?

The process by which a sense organ converts physical energy into electrical signals that become neural impulses sent to the brain.

What is adaptation in sensation?

The decreasing response of the sense organs as they are exposed to a continuous level of stimulation.

How is sensation defined in this lecture?

Relatively meaningless bits of information that result when the brain processes electrical signals from the sense organs.

How is perception defined in this lecture?

Meaningful sensory experiences that result after the brain combines hundreds of sensations.

What is the visible spectrum?

A segment of electromagnetic energy we can see because its waves stimulate receptors in the eye.

What is the cornea?

The rounded, transparent covering over the front of the eye that bends light into a narrower beam.

What is the pupil?

The round opening at the front of the eye that allows light to pass into the interior.

What is the iris?

The circular muscle surrounding the pupil that controls how much light enters the eye.

What is the lens?

A transparent oval structure whose curved surface bends and focuses light; its curvature is adjusted by muscles.

What is the retina?

The thin film at the back of the eye containing photoreceptors; site of transduction.

What are rods?

Photoreceptors for low light that contain rhodopsin and are extremely light-sensitive; mainly perceive black, white, and gray.

What are cones?

Photoreceptors for color and detail that contain opsins; concentrated in the fovea and wired one-to-one to ganglion cells.

Where are most cones located in the retina?

In the retina’s fovea.

What is rhodopsin?

A photopigment in rods activated by small amounts of light.

What are opsins?

Photopigments in cones that enable color vision when activated by bright light.

What is the role of the thalamus in vision?

Relays visual impulses to the occipital lobe after crossing at the optic chiasm.

What is the optic nerve?

Nerve that carries impulses out of the eye; its partial crossing creates the optic chiasm and a blind spot.

What is the blind spot?

The area where the optic nerve exits the retina, containing no photoreceptors.

Where is the primary visual cortex located?

At the back of the occipital lobe; transforms impulses into simple visual sensations.

What are visual association areas?

Areas next to V1 that add meaning to simple visual sensations.

What are the two main theories of color vision?

Trichromatic Theory and Opponent Process Theory.

What does the Trichromatic Theory propose?

Color vision results from three types of cones sensitive to red, green, and blue.

What does the Opponent Process Theory propose?

Color vision arises from opposing retinal processes (red-green, blue-yellow, black-white).

What is color blindness?

Inability to distinguish two or more shades; includes monochromats and dichromats.

What is a monochromat?

Person with total color blindness, seeing only black, white, and gray.

What is a dichromat?

Person with two kinds of functioning cones (or only one kind); often red-green color blindness.

What do sound waves vary in that relate to loudness?

Amplitude (height) of the waves.

What does frequency determine in sound?

Pitch, the perception of how high or low a sound is.

What is a decibel?

A unit for measuring loudness; range from 0 dB to about 140 dB.

What comprises the outer ear?

Pinna, auditory canal, and tympanic membrane (eardrum) that collect and funnel sound.

What is the tympanic membrane?

A thin membrane (eardrum) that vibrates in response to sound waves.

What are the ossicles?

The three tiny middle-ear bones: malleus (hammer), incus (anvil), stapes (stirrup) that amplify vibrations.

What is the oval window?

The membrane connected to the ossicles that transmits vibrations into the cochlea.

What are the two main structures of the inner ear?

Cochlea (hearing) and vestibular system (balance).

What is the cochlea?

A snail-shaped organ in the inner ear where transduction occurs via hair cells.

What are hair cells?

Hair-like receptors on the basilar membrane that transduce mechanical energy into neural impulses.

What is the basilar membrane?

The bottom membrane of the cochlea whose movement bends hair cells.

What is the auditory nerve?

Nerve fibers that carry impulses from the cochlea to the auditory cortex.

Where is the primary auditory cortex located?

In the temporal lobe; processes basic auditory sensations.

What is the auditory association area?

Area that interprets meaningless sounds into meaningful perceptions like language and music.

What is the vestibular system responsible for?

Sensing head position, keeping the head upright, and maintaining balance.

What are semicircular canals?

Canals in the vestibular system filled with fluid that respond to head movement.

What is motion sickness attributed to?

A sensory mismatch between vestibular information and visual information.

What is Meniere’s disease?

Malfunction of the semicircular canals causing dizziness, nausea, and sometimes tinnitus.

What are taste buds?

Receptors on the tongue for five basic tastes (sweet, salty, sour, bitter, umami) that perform transduction.

What are the five basic tastes?

Sweet, salty, sour, bitter, and umami.

Where are taste receptors located?

Taste buds on the tongue; impulses reach the brain’s parietal lobe.

What is olfaction?

The sense of smell; receptors detect chemicals and transduction occurs to neural signals.

Where are olfactory receptors located?

In patches of tissue in the upper nasal passages (olfactory epithelium).

What is the olfactory bulb?

A relay area above the olfactory receptors that sends impulses to the primary olfactory cortex.

What is the primary olfactory cortex?

The piriform cortex located beneath the brain; interprets olfactory impulses.

What is the sense of touch composed of?

Pressure, temperature, and pain detected by skin receptors that transduce to nerve impulses.

What are Pacinian corpuscles?

Large, fast-adapting touch receptors in the fatty layer; highly sensitive to vibration.

What are free nerve endings?

Nerve endings around hair follicles involved in temperature and pain; show adaptation.

What is the somatosensory cortex?

A region in the parietal lobe that maps touch, temperature, and pain across the body.

What does transduction in touch involve?

Conversion of mechanical pressure or temperature into neural impulses.

What are the layers of skin relevant to touch receptors?

Outer dead layer (no receptors), middle layers with varied receptors, deeper fatty layers with Pacinian corpuscles.