Sensory Lab

Nonhuman Senses

• Infrared imaging

• Electrosense

• Vomerolfaction

• Ultrasound detection

• Infrasound detection

• Magnetoreception

• Cutaneous chemosense

Sen

sory

Pat

hw

ay

3. A signal is then sent to the effectors (specific muscle groups).

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.

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 ReflexThe 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 ReflexesBlink 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.

4) Record your observations and compare your threshold with other members of the class

Salty & Sweet

Sour

Bitter

Umami

Fattiness

Calcium RINSE YOUR MOUTH BETWEEN TASTES!!

Piquance

Chemosense: Smell Smell receptors are located in

upper portion of nasal cavity

Characteristics: 1. Sense of smell shows high

degree of adaptation2. Certain odors mask others

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.)

Experiment:

Cutaneous Sensations: TouchJust 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

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.

Finger Back of Neck

DON’T WATCH!!!

Cutaneous SensationsExperiment:

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: TouchExperiments:

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.

Finger Back of Neck

DON’T WATCH!!!

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 vibrateagainst membrane

(oval window)

Ion channels open and cause a receptor potential along auditory nerve

0

Oval window sets

fluid of the cochlea

into motion

Specific portions of the basilar membrane (in the cochlea) move in response to the movement of the

cochlear fluid

Deafness

Nerve deafness:

Due to abnormalities of the cochlea and neural mechanisms

Conduction Deafness:

Due to abnormalities of the auditory canal, tympanic membrane, or ossicles

Mechanoreception - HearingExperiments:

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. Whirl until dizzy2. Attempt to quickly

strike the outstretched finger of partner with your finger

3. Record the direction in which you over-corrected your attempt to make contact

VisionBlind 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