BIO122 SENSATIONS, VISION, HEARING, TASTE ACTIVITIES

relative receptor density activity

used small probes to check hot, cold, and touch receptor density. most abundant was touch. more cold than warm

activity 2 (two point discrimination/threshold test)

used calipers to distinguish two points as distinct. fingertips and lips have the greatest density of touch receptors, thus having the smallest two-point threshold

activity 3 (tactile localization)

with eyes closed, the subject's palm is tapped with a marker. the subject then needs to touch the exact point that was tapped. repeated trials did not improve accuracy because the receptor density did not change. areas with greater receptor density had more accurate localization

activity 4 (adaptation of touch receptors)

stacked a coin on the subject's forearm and asked if sensation continued over time. no sensation felt overtime = adaptation. sensation returns once more coins were stacked. sensation is greater when hair springs back

'2 cutaneous sensations studied in lab

touch and pressure

'in lab the test in which calipers are used to distinguish when one sharp point or two perceived as distance between the ends of the calipers are changed is called

two point discrimination/threshold test

activity 1: demonstrating the blind spot

an X is next to a dark circle. the left eye is closed and the right eye is lined up directly looking at the X. As the book gets closer, the dark circle on the right disappears, showing the blind spot

activity 2: determining near point of accommodation

best if using subjects of various ages. measures the closest distance an object stays in focus. younger subjects will have a smaller near point of accommodation. the lens loses flexibility with age

activity 3: testing visual acuity (snellen chart)

standing 20ft away from the chart, cover one eye and read the snellen chart. repeat with other eye. 20/20 is what a normal person sees at 20ft

activity 4: testing for astigmatism

look at the center of the chart with one eye. the lines radiating from the center should be equally dark. those with astigmatism would see lines of various thicknesses

activity 4: brain lesion effects on sight

• a lesion on the right optic nerve affects the medial and lateral vision of the right eye

• a lesion to the optic chiasma affects the medial vision of both eyes

• a lesion to the left optic tract affects the left lateral eye and the right medial eye vision

• a lesion to the visual area of the right cerebral cortex affects the right lateral eye and left medial eye vision

activity 5: testing for color blindness

viewed the ishihara color plates in a bright light, at a distance of 30 inches and 90 degrees to your line of sight. takes about 3 seconds to note the number of each plate

activity 6: testing depth perception/binocular vision

insert a pencil into a test tube with both eyes open, then with one eye closed. when one eye is closed, depth perception if lost and the task is more difficult

activity 7: reflex activity of intrinsic and extrinsic eye muscles (photopupillary reflex)

observe the response of a bright light shined into the eye. the pupil should constrict. in distant viewing, the eyes look straight and the pupils dilate. in near viewing, the eyes look medially and the pupils constrict

activity 8 (conducting ophthalmoscope examination)

preferably done with a subject and examiner of 20/20 vision, using green light setting, and viewing the right eye using right eye, get to within a couple of inches and look thru the side of the pupil. Look at the macula quickly for a second, optic disc may also be visible as well as blood vessels.

'the ___ chart was used in the lab to show irregularities in curvature of the lens/cornea

astigmatism

'in the accommodation pupillary reflex test done in the lab, what was the reaction of looking and focusing at a distant object and at a very close object by the pupils

pupil dilation for distant object and pupil constriction for close object

'in the convergence reflex test done in the lab, what was the reaction of looking and focusing at a distant object and the focusing on a very close object by the eyes?

regular eye movement followed by convergence/medial eye rotation

'the ___ reflex is observed by sudden illumination of the retina by a bright light, causing the pupil to constrict in direct proportion to light intensity

photopupillary

activity 2: examination of the ear using the otoscope

hold the subject's head and insert the speculum, which is attached to the otoscope, into the external auditory canal. the canal itself and the tympanic membrane can be seen

activity 4: acuity test for hearing

pack one ear with cotton, bring a ticking clock to the unpacked ear and slowly move away to find when the sound stops being heard. we find that the threshold of audibility is indefinite

activity 4: sound localization

with the subject's eyes closed, take a ticking clock and ask the subject to point where the sound originates. more difficult when the sound is at equal distance to both ears

activity 4: frequency range of hearing

exposed the subject to sounds of different frequencies. done by hitting a tuning fork with a rubber mallet and asking which sounds were heard best. lower frequencies are usually heard better

activity 4: weber deafness test (conduction and sensorineural)

place a tuning fork that has been struck on the top medial part of the subject's skull. hearing it equally in both ears is normal. if it's heard louder in one ear than the other, there's conductive deafness

activity 4: rinne deafness test (comparing bone and air conduction)

first place the tuning fork on the mastoid process until inaudible and then to the ear itself. if sound can be heard, hearing is normal. next start at the ear (indirectly in the air) and listen to the tuning fork until inaudible, then place on the mastoid process, if sound is heard, then the subject has conductive hearing loss

activity 7: balance test

walk in a straight line. no dizziness or wobble = normal

activity 7: barany test (nystagmus and vertigo)

rotate the seated subject quickly in a rotating stool. stop the spinning and observe their eyes for nystagmus. then observe for vertigo when the subject stands.

activity 7: romberg test

have subject stand with their back to a blackboard. draw parallel lines on either side of them. have them stand with eyes open and then eyes closed for 2 mins. when the eyes are open, there is little movement. with the eyes closed, there is some swaying and movement of several inches from the marked parallel lines. do the same when making the subject stand with one shoulder touching the blackboard. draw parallel lines as well and observe movement with eyes open and closed

activity 7: role of vision on maintaining equilibrium

raise one foot about 30cm above the ground while eyes are open and then while eyes are closed. hard to maintain balance with eyes closed

'what is the device used in the audiometry test

audiometer

'audiometry

determines hearing acuity

'lab test for equilibrium that spun a subject quickly and halted them abruptly to see nystagmus is called

barany test

'the lab test that checked equilibrium with eyes opened and closed by drawing lines on the blackboard as the subject swayed is called

romberg test

'the rubber mallet was used to perform what hearing test?

frequency range of hearing

'an individual with the genotype TT for the PTC tasting gene would be a ___

taster

'an individual with the genotype Tt for the PTC tasting gene would be a ___

taster

'an individual with the genotype tt for the PTC tasting gene would be a ___

non taster

'PTC like chemicals are found in the ___ family of vegetables

brassica; ex: cabbages

'receptors like those of olfaction and taste that respond to chemicals in solution are called ___

chemoreceptors