Lab Quiz 3 Flashcards
Cornea
Transmits and refracts light, is curved, air-cornea interface
Iris
Controls amount of light entering eye
Circular muscles
Constrict pupil controlled by parasympathetic nervous system
Radial muscles
Dilate the pupil controlled by sympathetic
Lens
Focuses light on retina, involved in accommodation
Accommodation
Ability of the lens to keep an object focused on the retina as distance to the object varies
Distant vision
Over 20 ft away, ciliary relaxed suspensory taut/stretched lens thin/flat
Close vision
Ciliary contracted, suspensory relaxed, lens round/thick
Near point of vision
Minimum distance from the eyes an object can be brought into focus
Presbyopia
Loss of accommodating ability with age, less flexibility of lens zonular attachment moves forward, lens can’t thicken for close vision
Retina
Layer of neural tissue with photoreceptors
Rods
Extremely light sensitive, black/white vision, low resolution
Cones
Require more light, color, high resolution
Cone types
S cones: short wavelengths, blue
M cones: medium wavelengths, green
L cones: long wavelengths, red
Cone defects
Leads to color blindness, inherited or from damage to the neural pathway, Red green is most common
Optic nerve
Collection of axons from the retinal ganglion cells that exits eye
No rods or cones → blind spot
Fovea centralis
In the macula lutea best visual acuity, only cones no other layers so light falls directly on cones
Saccadic movements
Shifts parts of visual field onto fovea
Convergence
Rods snaps w/ one bipolar, many bipolar w/ one ganglion
Increases dim light sensitivity but low acuity
Nystagmus
Tone of one of six muscles that keeps eyes in midline position is weak causing eyes to drift slowly in one direction followed by a rapid movement back to correct position
Rhodopsin
Photo sensitive chemical in rods
11 cis to all trans in light
Has to rebuild before receptor can be stimulated again
Positive afterimage
Eye adapted to bright light, bright image still seen from continued firing of photoreceptors
Negative afterimage
Dark image of lightbulb seen on light background from breaching of rhodopsin
Afterimage colors
R →g
B →o
Y→p
Sound waves
Alternating zones of high and low pressure traveling through a medium
Frequency
Cycles per second in hertz, pitch
20-20, 000 for humans
Loudness
Intensity in decibels, loudness
Amplitude of wave humans 0 - 80 dB
Outer ear
Pinna (auricle) and external auditory meatus, auricle funnels in sound waves into eam which channels them to tympanic membrane
Malleus and stapes
Malleus attached tympanic, stapes to oval window
Ossicles
Transmit vibration from middle to inner ear
Inner ear
Cochlea and vestibular apparatus
Conduction deaf
Sound waves to oval window impaired many causes
Sensorineural deaf
Impulses from cochlea not conducted to auditory cortex, certain frequencies
Rinne’s
Tuning fork on mastoid move to outside ear
Hear sound outside ear → normal, air greater than bone
No sound → either type of deafness bone conduction greater
Weber’s
Tuning fork on midsagittal of skull
Normal → equal sound both sides
Middle ear prob → affected ear sounds louder due to conduction deafness
Inner ear → sound in affected ear softer from sensorineural dearness
Vestibular nystagmus
Involuntary eye movements from vestibular inputs
Muscle function
Convert chemical energy to mechanical work
Fiber to neuron
Motor neurons innervate many fibers, each fiber innervated by only one motor neuron
Motor unit
Single motor neuron and all fibers that it innervates
Finer muscle control
Smaller motor units
Strong contraction
Larger motor units
Contractions of high strength
Recruitment of larger and larger motor units
Smooth controlled movements
Graded contractions according to load placed on muscle
Tonus
Constant slight tension to keep muscle ready
Degree of muscle contraction
of motor units activated, frequency of stimulation
Twitch
Single shock, quickly contracts then relaxes
Latent period
Time between stimulus and start of contraction
Contraction phase
End latent to muscle tension peak
Relaxation
Peak tension to end contraction
Summation
Second twitch will partially add on top of first with second shock
Incomplete tetanus
Relaxation time decreasing with more frequent shocks
Complete tetanus
Frequency where there is no relaxation
Treppe
Staircase effect
Electromyography
Uses surface electrodes to detect, amplify, and record changes in skin voltage produced by underlying muscle contraction
Recording → EMG
Muscle fatigue
Reversible exercise -induced reduction in muscle’s ability to generate force
Dynamometer
Measures muscle force
% Increase in clench
(Strongest - weakest)/weakest x 100
