Sensory
Lab
Nonhuman Senses
• Infrared imaging
• Electrosense
• Vomerolfaction
• Ultrasound detection
• Infrasound detection
• Magnetoreception
• Cutaneous
chemosense
Sensory Pathway
1. Stimulus is detected by a sensory neuron or
specialized receptor cells. The receptor cell converts
stimuli into an electrical signal.
2. This
action
potential is
now sent to
the CNS
for
integration.
3. A signal is then sent to the effectors
(specific muscle groups).
Reflexes
Functions that should happen while you are free to
think about other matters!!
Best known Tendon Reflex:
Patellar Reflex
Other Reflexes to test today:
Blink Reflex
Light Reflex
Grasp reflex in infants
Patellar Reflex
The tendinous attachments of
muscles have special sensory
receptors:
• Attachment receptors respond to
stretch stimuli
• Receptors relay info to the CNS
• Nerve impulses pass up to the
spinal cord and through a synapse
to the a motor neuron and then to a
nearby muscle—reflexive
response impulses never reach
the brain!!
You will quantify the strength of the patellar reflex in response to different stimuli.
Specific Reflexes
Blink Reflex:
As an object comes near
the eye the eyelids rapidly
close to protect the eye.
You will observe this
reflex reaction.
Light Reflex:
The iris contracts and
relaxes controlling the
amount of light allowed
through the pupil. You
will measure the dilation
of the irises under various
light conditions.
Chemosense: Taste
EXPERIMENT:
1) Locate the various types of taste
receptors
2) Diagram the surface of the tongue
and identify the regions where the
taste sensations are most strongly
experienced.
3) Determine your threshold for salt and
sugar using concentrations of
varying intensities.
Umami
Fattiness
Calcium
Sour
Bitter
Piquance
4) Record your observations and
compare your threshold with other
members of the class
Salty
&
Sweet
RINSE YOUR MOUTH BETWEEN TASTES!!
Chemosense: Smell
Smell receptors are located in
upper portion of nasal
cavity
Characteristics:
1. Sense of smell shows high
degree of adaptation
2. Certain odors mask others
Experiment:
1. Close your eyes and distinguish the odors
2. Smell the camphor until the odor can no longer be detected
and then try to distinguish between oil of cloves and oil of
peppermint. (Repeat with alcohol as masking agent, and
compare the ability of the two substances to affect your ability
to distinguish.)
Cutaneous Sensations: Touch
Just a touch of information:
A given neuron can have a small or
large receptor field over which a
stimulus can affect it
“Sensitive areas” (ex. fingers) contain
the highest density of touch
receptors
Finger
Back of Neck
DON’T WATCH!!!
Experiments:
Distribution of receptors:
1. Mark your: palm, back of hand, back
of arm and back of neck
2. Using an aesthesiometer, stimulate
each ink spot with a minimal and
CONSISTENT stimulus. Locate
those areas with the highest
concentration of sensitivity (touch
receptors) and try to quantify the
differences between body parts.
•
With a pithing needle locate
the distribution of pain receptors
in the same area you did with
the touch receptors
•
Also locate the distribution of
temperature receptors using
one each of cold and warm
glass rods.
Cutaneous Sensations
Experiment:
Warning!!
1. Make sure the intensity isn’t too strong (no one should feel
too much pain!)
2. Use consistent intensity throughout the entire experiment
Cutaneous Sensations: Touch
Experiments:
Tactile Discrimination:
1. Determine a person’s ability
to distinguish two distinct
stimuli using a compass.
2. Make sure the two areas are
applied simultaneously.
3. Quantify the differences in
tactile ability among different
parts of the body.
DON’T WATCH!!!
Finger
Back of Neck
Cutaneous Sensations: Temperature,
intensity, and thermal adaptations
Experiments:
1.
Survey areas on the ventral and dorsal
surfaces of forearm with a cold glass
rod
--Determine whether there are
differences in intensity of cold in
different areas.
2.
Set up three beakers:
Hot water, room temperature water,
cold water.
Place one index finger in the hot and
one in the cold water, then place both in
the room temperature water.
Compare the sensations.
Mechanoreception - Hearing
Sound waves enter
ear through
auditory meatus
Tympanic membrane
moves back
and forth
Movement of tympanic
membrane is transmitted
to ossicles
Ossicles vibrate
against membrane
(oval window)
Oval window
sets
fluid of
the cochlea
into motion
Ion channels open and
cause a receptor potential
along auditory nerve
0
Specific portions of the basilar membrane
(in the cochlea) move in response to the
movement of the cochlear fluid
Deafness
Conduction Deafness:
Due to abnormalities of the
auditory canal, tympanic
membrane, or ossicles
Nerve deafness:
Due to abnormalities
of the cochlea and neural
mechanisms
Mechanoreception - Hearing
Experiments:
Webber’s Conduction - Deafness test:
Place the handle of a vibrating tuning fork
on the mastoid process.
When sound can no longer be heard move
the fork to the front of the ear.
Localization of Sound:
Attempt to locate the position of a time clock
held in different positions
Repeat with one ear closed; record the
position of the clock when you could and
could not locate it.
Cochlear Implant
Mechanoreception - Balance
Balance is determined by
the movement of fluid, the
endolymph, in the labyrinth
(a complex set of tubing in
the inner ear)
Movement of the endolymph
causes nerve impulses
which are signals to the
brain indicating motion,
direction of motion, etc.
Mechanoreception - Balance
Experiment:
1.
2.
3.
Whirl until dizzy
Attempt to quickly
strike the outstretched
finger of partner with
your finger
Record the direction in
which you over-corrected
your attempt to make
contact
Vision
Blind Spot
+
●
Visual Acuity
Myopia and Hypermetropia
Myopia:
Occurs when the lens is too convex or the eyeball is too long
Hypermetropia:
Occurs when the eyeball is too short, the lens is too flat, or there is a
corneal imperfection,
Astigmatism
Other Vision Experiments
• Accommodation
• Eye Dominance
• Afterimages
In your lab report:
•
•
•
•
Abstract
Experimental (brief, but include all)
Results/Observations
Discussion w/ study questions
• Next week: Muscles