Sensory Lab (Lab 6)

What would the significance of this difference be in terms of our sense of touch on different parts of the body? Give an example from everyday life that supports your conclusion.

Finger = higher density

What is the term for this phenomenon?

Sensory adaptation

What produces the purkinje tree?

Shadow of the retinal blood vessels

What do your results suggest about the size of tactile receptive fields in each area?

Smaller receptive fields on fingertips, larger in other areas

Note that the tube does not actually claim to cool the area. It claims to be a local analgesic (pain reducing agent.) How might menthol work as an analgesic?

1. Menthol may bind and inhibit nociceptors. 2. Gated theory of pain- with cool sensation streaming up sensory neurons, it may close the "gate" on pain sensation

You will need to know the 5 components of a reflex arc. Match the temporal order on the left to its component on the right, beginning with stimulus and ending with response:

1. Stimulus induces threshold in sensory receptor 2. Afferent nerve fiber sends signals to CNS 3. CNS (spinal cord) integration center 4. Efferent nerve fiber sends signals to effector 5. Effector (muscle or gland) responds

How many different types of taste receptors do we have?

5- sweet, salty, bitter, sour, umami

Equilibrium, or sense of balance, depends on input from which system? -Vision -Proprioception -Vestibular System

All of these are correct

Taste and Smell:

Chemoreceptor

High threshold, not sensitive in low light, color, central retina:

Cones

Which of the statements is NOT true regarding the two point discrimination test? -Fingertips have large receptive fields -Fingertips have high receptor density -Small receptive fields and large receptor density are characteristic of high sensitivity -Compared to the fingertip, the back of the arm has. lower receptor density and larger receptive field

Fingertips have large receptive fields

What might account for differences in thresholds among your classmates?

Genetics- genetic differences in the density and/or sensitivity oof the various taste receptors

What do your results suggest about the number of tactile receptors located in each area?

Higher density (number) of tactile receptors on fingertips, lower in other areas

Based on this experiment, what might be different about the stimulus threshold for roods vs. cones?

Rods: very low threshold (which means highly sensitive to light so they work in diim/dark light) Cones: high threshold (which means not very sensitive so they only work in bright light)

How does warming food enhance the flavor?

It enhances aromatic compounds becoming vapors that act on olfaction

What accounts for the blind spot?

It is where the optic disc is. There are no photoreceptors in the optic disc

Whats the usual stimulus to the retina?

Light-photons

Why would vestibular and visual inconsistencies result in nausea and vomiting?

Many neurotoxins also produce visual and vestibular discrepancies so nausea prevents from consuming more toxin and vomiting rides the body of the toxins

In the powerpoint, you saw that the threshold for bitter is very low. What is the leading theory for this low threshold, and why does bitter induce vomiting?

Many plant toxins are bitter alkaloids so we know to avoid them, or if bitter s high enough, it induces vomiting to bid the body of toxins

Proprioception:

Mechanoreceptor

Select the statement that does NOT fit in explaining why properly placed pressure on the eyelid can induce the perception of light: -All signals (action potentials) sent by the optic nerve are perceived as light in the visual cortex -Properly placed pressure can physically depolarize photoreceptors -Light is the normal sensory modality for photoreceptors in the retina -Mechanoreceptors in the eyelid send signals to the visual cortex

Mechanoreceptors in the eyelid send signals to the visual cortex

If the fast freeze does not actually cool the area, how might menthol produce the perception of cool?

Menthol binds and stimulates the cool receptor

Can you still walk along the line? What other sensory systems must make up for altered vestibular input? If your vestibular system were damaged, how well could other sensory systems compensate?

No. Visual and proprioception could coordinate

Pain sensation:

Nociceptor

Was there any significant difference between the surface T of the hand sanitizer control area and the fast freeze test area?

Not typically. Some groups showed cooler temps with fastfreeze-prbobably experimental artifact and not significant

Purkinje tree shadow:

Retinal blood vessels

Low threshold, highly sensitive, black and white, periphery of retina:

Rods

What does this experiment say about the location of rods and cones in the retina?

Rods- periphery of retina. Cones- center of retina

Blind spot:

Optic nerve/optic disc

Select the statement that is NOT true regarding tonic and phasic receptors and sensory adaptation: -Light touch, odors, and moderate temperature changes are all rapidly adapting sensory modalities -Tonic receptors sustain sensory signaling for the duration of the stimulus -Phasic receptors allow us to "phase out" unimportant sensory information -Phasic receptors report new or changing information, but do not fire for the duration of the stimulus -Pain is transmitted via rapidly adapting phasic receptors

Pain is transmitted via rapidly adapting phasic receptors

What type of receptors are involved?

Phasic

Vision:

Photoreceptor

Why do two so very different types of stimuli to the eyes, light and touch, give rise to similar sensations?

Pressure on the eyeball is transmitted through the vitreous to the retina where the retina physically depolarizes photoreceptors. All action potentials on the optic nerve are interpreted as light

Make a list of all of the things that one must be aware of in order to successfully walk across a balance beam.

Proprioception, visual, and vestibular systems

What other sensations contribute to overall palatability of food?

Texture, visual appeal

Two very different phenomena - bitter taste and visual/vestibular discrepancies - can both induce vomiting and it is theorized that this is for the same evolutionary reason. Select the statement below that does NOT support this evolutionary origin of vomiting hypothesis: -Many plant toxins are alkaloids which are bitter -Of the 5 taste sensations, bitter has the lowest threshold -The human body has a high tolerance for bitter compounds -Visual/vestibular discrepancies can induce vomiting -Motion sickness and toxins (such as alcohol) can cause visual/vestibular discrepancies

The human body has a high tolerance for bitter compounds

Why do we normally not appreciate a blind spot?

The retinal fills in what it "thinks" should be there

Why does the vestibular system continue to signal rotational movement even though the movement has stopped?

The vestibular fluid continues to spin by inertia. This signals the brain that the body is still spinning and so the eyes go into nystagmus to attempt to focus

Hot & Cold:

Thermoreceptor

Hold your lab manual at arms length and begin reading. Now move the manual from side to side, about bone foot to the left and one foot to the right of center. Are you able to read the page?

Usually not

Now, holding the manual at the same distance, begin reading, and move your head from side to side. Now are you able to read the page? As your head moves from side to side, are your eyes moving with the head?

Usually yes. The eyes are not moving with the head. They are locked in focus on the object via the VOR.

In the wrap-up, you saw a video of a patient with dysfunctional proprioceptors. This video demonstrated the importance of what sensory systems in balance?

Visual and Vestibular

How many different types of olfactory receptors do we have?

We have at least 400 genes for olfactory receptors

What is the leading theory for why we do not see the Purkinje tree with normal vision?

When light enters through the pupils in normal vision, it sets up a reflex whereby the retina (or maybe the brain) suppress the image of the retinal blood vessels shadow. We shined a string light through the side of the eye and by-passed the pupil

Why does plugging the nose alter the taste of flavor of a substance?

With nose plugged, we only appreciate basic taste because aromatic molecules cannot waft up to the olfactory neurons which account for flavor