The flashcards below were created by user
Dnuorgrednu2
on FreezingBlue Flashcards.
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Astigmatism
Blurry images at all distance; unequal curves on lens and/or cornea, creating discontinuous image on the retina
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Outer segment
Contain membrane-bound discs with pigments that absorb and react to light
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Rods
Pigment discs stacked like pennies all the way to the base, membranes are DISTINCT from the plasma membrane
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Cones
Pigment discs taper off toward the base, membranes are CONTINUOUS with the plasma membrane
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Opsin
Trans membrane protein in in the membrane of pigmented discs of rods and cones
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Retinal
- Light absorbing molecule that changes shape when struck by a photon of light
- Vitamin A = precursor to retinal
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Rhodopsin
- Visual pigment in rods
- Membranes of pigmented discs of outer segment
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Bleaching of pigment
Breakdown of rhodopsin after thew absorption of light
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Excitation of Rods
- Rhodopsin
- Bleaching of pigment
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Excitation of cones
- Photopsins
- Different colors
- Color blindness inherit gene for one of the photon proteins that is deficient, most common are red and green mutations
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Photopsins
3 distinct pigments in cones are sensitive to 3 different parts of the visible spectrum
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Blue cones
Maximum sensitivity at 455nm
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Green cones
Maximum sensitivity at 530nm
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Red cones
Maximum sensitivity at 625nm
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Different colors
Differential activation of each of the three different cones
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Light adaptation
- From very dark to very bright
- Rhodopsin in rods is quickly bleached out
- Cones are activated to take over (5min)
- Consensual pupil reflex - constriction
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Dark adaptaion
- Very bright to very dark
- cones are gradually cease to be stimulated
- Bleached out rods can produce rhodopsin
- Pupillary dilation - pupils increase in size
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Nyctalopia
- Night blindness
- Deficiency in function of rods during dim-light situations
- Vitamin A deficiency in general cause
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Binocular vision
Two eyes have overlapping regions of the visual field, so that the same point is seen from slightly different angels
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Depth perception
A result of binocular vision in which person can perceive relative distances based on information gather in both eyes
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Vibration of medium
- Sound travels in compression waves through a particular medium
- Solid = fastest
- Gas = slowest
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Sound as a wave
The series of high pressure and low pressure areas are called "compressions" and "rarefactions", respectively/
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Sine wave
Graphic representation of areas of compression and rarefaction of a sound wave
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Wavelength
The distance between 2 areas of compression for a given sound wave
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Frequency
The number of waves that pass a given point in one second (1/s = hertz)
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Wavelength and frequency
- Short wave/high freq = high pitched tones
- Long wave/low freq = low pitched tones
- Human freq range = 20hz - 20khz
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Amplitude
- Intensity of energy in a given wave of sound
- Signified by height of sine wave
- Loudness - subjective interpretation of intensity of a sound
- Decibel - Logarithmic scale to measure the intensity of sound wave
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Human amplitude range
0dB - 120dB (130dB = pain level)
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Resonance
Different fibers of basilar membrane have different "natural freq"
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Basilar membrane
- Fibers of different lengths, thickness, and tension like strings of a piano
- Specific parts of basilar membrane vibrate only at specific freq (pitch)
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Cochlear hair cells
Rest on the basilar membrane, contain "sterocilia" which project into the "tectorial membrane"
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Perceiving Pitch (freq)
Location of vibration on the basilar membrane
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Perceiving difference in loudness (intensity)
Amplitude increases, more hair cells of the basilar membrane (with same pitch) are activated
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Localizing source of sound
- Superior olivary nucleus
- Relative intensity
- Relative timing
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Superior olivary nucleas
First point where sound from both ears come together
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Relative intensity
The amplitude of sound waves hitting the different ears
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Relative timing
The difference in timing in which a sound reaches both ears
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Conduction deafness
- Disruption in sound vibrations to basilar membrane (ext & mid ear)
- Caused by:
- Blocked auditory canal (wax, fluid)
- Perforated tympanic membrane
- Otitis media
- Otosclerosis
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Otitis media
Middle ear infection/inflammation
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Otosclerosis
Hardening of the earbone joints
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Sensorineural deafness
- Disruption anywhere in pathway from hair cells to the auditory cortex
- Caused by:
- Loss of hair cells (explosion)
- Dmg to vestibulochochlear nerve (VIII)
- Dmg to nuclei/tracts to the cortex
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Tinnitus
- Chronic perception of clicking or ringing
- Cause by:
- Sudden blow to the tympanic membrane
- Gradual deterioration of afferents in chochlear nerve
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Menierre's Syndrome
- Effects both hearing and balance
- Results in tinnitus, vertigo, and interspersed nausea and vomiting
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Linear movement
- Vestibule
- Horizontal acceleration
- Vertical acceleration
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Vestibule
Bony cavity of the inner ear between the chochlea and the semicircular canals
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Saccule and Utricle
Smaller sacs housed within the vestibule
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Maculae
Patch of supporting cells and hair cells along the utricles and saccules
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Hair cells
- Like hair cells of basilar membrane
- Respond when bent
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Otolithic membrane
Jelly like sheet that abuts the stereocilis of the hair cells
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Horizontal acceleration
- Maculae of UTRICLE is in the horizontal plane
- Hairs bend when motion in FORWARD/BACKWARD
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Vertical Acceleration
- Maculae of SACCULE is int he vertical plane
- Hair bend when motion is UP/DOWN
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Angular Movement
- Semicircular canals
- Crista ampullaris
- Change in angular (rotation) acceleration
- Vestibular nystagmus
- Vertigo
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crista ampullaris
like maculae, contain hair cells that respond to flow of endolymph in canals
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Change in angular (rotational) acceleration
Movement of the head in non-linear direction is monitored by three canals
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Vestibular nystagmus
Movement of eyes to remain fixed on object when on "merry-go-round"
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Vertigo
False feeling of gravity or motion
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Vestibular nuclei
- Also receive input from eyes and somatic proprioceptors
- Coordinates information to help control motion of eyes, neck, limbs
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Cerebellum
- Also receives input from eyes and somatic proprioceptors
- Coordinates information to help regulate head positon, posture, and balance
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Problems with Equilibirum
Dizziness, nausea, imbalance, vomiting
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Motion sickness
Conflict between visual/somatic inputs and action of the vestibular apparatus
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