Module 10: Special Senses Flashcards Preview

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Flashcards in Module 10: Special Senses Deck (313)
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301

Miosis vs Mydriasis

Miosis - Parasympathetic stimulation; sphincter muscle to constrict the pupil

Mydriasis - Sympathetic stimulation ; radial fibers to cause dilatation

302

Direct vs. Consensual

Direct reflex: shining light directly on pupil will constrict it

Consensual reflex: shining light on one pupil will constrict the other pupil as well

303

• Only 3 types of color pigments: Blue, Green, Red
• Selectively sensitivity to different colors
• Opsin of cones- photopsin
• color-sensitive pigment- retinal +photopsin

Color Vision

304

Tricolor Mechanism of Color Detection

• Spectral sensitivities of the 3 types of cones
• Ratio of cones stimulated

305

Perception of White Light

• Equal stimulation of all red, green, blue cones
• No single wavelength of light
• Proper combination of the 3 cones about equally

306

• Unable to distinguish some colors from others
• Absence of a single group of cones
• X-linked genetic disorder- exclusively in males

COLOR BLINDNESS

307

Types of Color Blindness

• Protanope
- loss of red cones
- Shortened wavelength

• Deuteranope
- loss of green cones
- Normal wavelength

• Blue weakness
- rare; blue cones are missing

308

Depth Perception (Based on 3 things)

1. Images of known objects
2. Moving parallax
3. Stereopsis- binocular vision
a. One eye is approximately 2 inches from the other causing a difference in what the two retinas perceive
b. Better judge of distance and depth when objects are nearby (vs one eye only)
c. Useless for depth perception at 50-200 feet

309

a. If one knows that a person being viewed is 6 feet tall, one can determine how far away the person is simply by the size of the person’s image on the retina.
b. brain has learned to calculate automatically

Images of known objects

310

a. As we move our heads or bodies, nearby objects appear to move more quickly than distant objects
b. Relative distances on different objects

Moving parallax

311

a. One eye is approximately 2 inches from the other causing a difference in what the two retinas perceive
b. Better judge of distance and depth when objects are nearby (vs one eye only)
c. Useless for depth perception at 50-200 feet

Stereopsis- binocular vision

312

• Proprioception+ vestibular function +vision

• VISION
- most significant contributor to balance
- bigger role than either of the two other intrinsic mechanisms

• Visual factors affecting balance
- clarity with which an individual can see
- size of the visual field
- susceptibility of the individual to light and glare
- poor depth perception

Balance

313

• Light resets the biological clock in accordance with the phase response curve (PRC).
• Can advance or delay the circadian rhythm, depending on the timing

Sleep-Wake Cycle