Physiology Sensory Lab QUiz

WHat was the sensation felt each hand when fingers were simultaneously transferred from cool (15°C) water and warm (40°C) water to water of intermediate temperature (30°C). Are the temperature sensations in each hand the same? If not, how are they different?

- Moving from 40°C to 30°C is a decrease in temperature so these fingers tend to feel cold/cool; - while moving from 20°C to 30°C is an increase in temperature so these fingers will feel warm. - One hand feels cold and the other hand feels warm, even though both hands are in the same 30°C water bath!

Binocular Vision: Describe the differences between the image of the clothespin when viewed with the. Right eye compared to both eyes and b. Left eye compared to both eyes.

- Much more of the three-dimensional shape of the object is visible when both eyes can focus on the object at the same time. - This provides the brain with information about the object from two angles at the same time.

Describe the sensation in each hand when fingers were transferred from 30°C and 40°C and both put into 15°C simultaneously. Which fingers experience the strongest sensation?

- One set of fingers experiences a decrease of 20°C, while the fingers of the other hand only experience a drop in temp. of 10°C. - The fingers experiencing the greatest drop in temperature should have the coldest sensation.

Blind Spot - Use the printed card to verify the presence of a blind spot in each eye. Is the blind spot physically medial or physically lateral to the fovea centralis on the retina? How do you know?

- The crystalline lens reverses images. - Since the object must be in the lateral part of the visual field to disappear, this must mean that the spot on the retina without sensory receptors is on the medial side of the center of the eyeball where the fovea centralis is located.

Describe and explain the sensation when one stethoscope tube is opened after being occluded while a vibrating tuning fork is held near the bell of the stethoscope. Does this demonstrate sensory adaptation? How?

- The sound gradually fades in the ear that is exposed to the sound, when the other stethoscope tube is opened; the sound is normally much louder in the ear that has not been exposed to the noise. - This is an example of auditory adaptation because the presence of a stimulus of constant properties produces less sensation in the ear continuously exposed to that stimulus of constant properties.

Place smallest to largest the distance felt through touch localization (amount of sensory receptors) - nape of neck - back of hand - fingers - upper arm

- fingers - neck - back of hand - upper arm

taste

- sensory receptors: Gustatory cells of the taste buds - sensory modality: chemoreceptors - specific stimulus: chemicals in solution - units/measurements of acuity: (no standard units)

touch localization

- sensory receptors: Meissner's corpuscles, Merkel's discs and Ruffini's corpuscles - sensory modality: mechanoreceptors - specific stimulus: pressure applied to two separate receptive fields - units/measurements of acuity: distance in mm (smaller number = greater localization ability)

hearing

- sensory receptors: cochlear hair cells of inner ear - sensory modality: mechanoreceptors - specific stimulus: Sound waves (vibrations) - units/measurements of acuity: decibels

sight

- sensory receptors: rods and cones in the retina - sensory modality: photoreceptors - specific stimulus: photons of light radiating or reflecting off of objects and activation of "edge detectors" - units/measurements of acuity: for the Snellen chart: feet away from an object at which a focused image can be produced

What is Aristotle's experiment?

If one rolls the marble under crossed fingers with one's eyes closed one can get the mental impression that there are two marbles, one marble under each finger.

what causes skin to be insensitive to that stimulus?

If there are no sensory receptors of a particular modality present in a particular patch of skin, then that skin will not be able to respond to stimuli of that modality

What pattern of results here would indicate an air conduction abnormality?

In people with normal hearing, air conduction of sound is usually more sensitive than bone conduction of sound. So, with the ear unplugged one should be able to hear the vibrations from the tuning fork through air after one can no longer sense them through bone conduction. Once the ear is plugged, one is simulating an air-conduction loss, and at this point bone conduction becomes superior to air conduction (which is has been lost); and one cannot hear the tuning fork through the plug after bone conduction has ended.

what is expected results of the Rinne test of sound conduction?

It is expected that in the plugged ear one can hear the tuning fork for a shorter time after it is removed from the mastoid process, compared to the normal ear.

Wherever the two-point discrimination is best (usually but not always on the tips of the fingers) that is the area in which the sensory receptors have the

SMALLEST receptive fields.

Describe the general property of sensory adaptation

Sensory adaptation refers to the property of sensory receptors losing their ability to continue to send action potentials to the CNS even though the stimulus is still continually present.

the hallmark of increased sensitivity/acuity

So the more sensory receptors with small receptive fields there are, the greater the ability of a given patch of skin to make fine discriminations

how is the sensation experienced in Aristotle's experiment produced?>

This sensation is produced because of the pattern of neural connections between the touch receptors in the fingers and the somatosensory cortex in the brain.

What do these observations tell us about the hearing of this subject? [i.e., normal, conduction deafness, nerve deafness, etc.?] Which results most directly point to your conclusion?

When the tuning fork is placed on the top of the head in the center of the skull, the degree of bone conduction should be the same in both ears. If the sound shifts to one side or the other, it indicates a lack of background noise (due to a lack of air conduction of sound) on the side to which the tuning fork sounds loudest. If a person has nerve deafness the sound will localize to the other (non-hearing loss) side under all conditions.

Weber test of sound conduction -With both ears unplugged, was the sound louder in one ear than the other? If so, in which ear?

ab same

The smaller the receptive field of each sensory receptor, the ---- two points can be and still cause separate receptors to become activated at the same time.

closer

Astigmatism

due to small imperfections in the curvature of the lens or cornea that cause parallel light rays to not remain parallel all the way to the retina.

Where is the touch receptor density the highest in the skin?

fingers

More acute senses need ---stimulus to be activated

less

Weber test of sound conduction -With the right ear plugged with cotton is the sound louder in one ear or the other? If so, in which ear?

louder in plugged ear

the touch localization ability should be LOWEST in the area of skin with the

lowest density of touch receptors (usually the back or the back of the upper arm).

give one example from this week's lab of slowly adapting (tonic) sensory receptors.

primarily visual receptors (objects on chart do not disappear even with prolonged gazing at chart),

Going from the skin of the fingers to the arm, what happens to touch receptor density?

progressively lower as one moves up the arm.

The higher the density of sensory receptors, the smaller the

receptive fields for each sensory receptor tends to be.

less acute senses require a --- stimulus for activation.

stronger

For Snellen Eye test, what is the d in the ration "d/D"

the distance (in feet) the subject is away from the chart of standard sized letters

For Snellen Eye test, what is the D in the ration "d/D"

the maximum feet away from the chart at which a "normal" eye can clearly see the letters in that line of type - exact value can vary between different specific charts

the ability to localize touch is directly proportional to

the number of different sensory receptors that are present in a particular patch of skin,

What occurs if if the fingers have gotten very acclimated to the 40°C water and a lot of the 40°C water is still on them when the hand is moved?

then it may take a second or two for the colder water to actually decrease the temp. of the fingers sufficiently to activate the cold thermal receptors. For those first brief seconds, the hand from the 30°C water may feel just slightly colder. When the cooler water actually gets to the skin of the other hand you should find that the hand from the 40°C water will then feel coldest.

give one example from this week's lab of rapidly adapting (phasic) sensory receptors.

thermal receptors (hands adapted within seconds to new temperature), auditory receptors (took longer, but eventually some diminution of hearing of constant),

Do people generally tend to have more touch receptors or thermal receptors in the skin of the forearm?

touch receptors

what could possibly allow for someone to have better depth perception in one eye?

with a lot of telescope experience (often in hunting) can actually have better depth perception with one eye that with both eyes.