Sponge: Set up Cornell Notes on pg. 43

Topic: 12.2 Touch: Pressure/Temperature

Essential Question:1. What happens when warm and cold receptors receive signals below 50o or above 115o?

2.1 Atoms, Ions, and Molecules

12.2 Touch: Pressure/Temperature

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Touch and Pressure Receptors

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Touch and Pressure Senses

1. Free nerve endings• common in epithelial tissues and are the simplest receptors

•sensation of touch/pressure/itching

2. Tactile (Meissner’s) corpuscles• abundant in hairless portions of skin

• lips, palms, fingertips, soles, external genital organs• detect fine touch- moving objects over skin;

distinguish between two points on the skin

3. Lamellated (Pacinian) corpuscles• common in deeper subcutaneous tissues, tendons, and ligaments

•detect heavy pressure and vibrations

The sense of touch and pressure derive from three kinds of receptors that sense mechanical forces that deform or displace tissue (MECHANORECEPTORS)

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Temperature Senses

Warm receptors•sensitive to temperatures above 77o F•unresponsive to temperature above 113oF

•rapidly adapt (sitting in a hot spa)Cold receptors

•sensitive to temperature between 50oF and 68oF•Unresponsive to temperatures below 50o

•rapidly adapt (swimming in the ocean)

Pain receptors• respond to temperatures below 50oF (freezing sensation)• respond to temperatures above 113oF (burning sensation)

Intermediate temperatures:•The brain interprets sensory input from different combinations of these receptors as a particular temp sensation

THERMORECEPTORS

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Lab Report 30:Receptors and General Senses

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• Complete Part A (on your own) using your notes, your book, and your lab manual

• Pg. 442-444 in book and notebook

Part A-Receptors (Fill in the blank)

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Part B- Sense of TouchObjective: To investigate the distribution of touch receptors in your lab partner’s skin1. Prepare a 2.5 cm square, with .5 cm on each side, on the inner wrist near the palm

2. Person #1 rests wrist on the table and closes their eyes

3. Take a sharp pencil and LIGHTLY touch a random square on your partner’s grid

4. Your partner will report when touch is felt+ = felt o = not reported

5. Test all 25 squares (RANDOMLY)

Make 2 other grids on other places on your partners body (upper arm, foot, lower leg, forearm, palm etc) Switch Partners.

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Part C Two-Point ThresholdObjective: To test your partner’s ability to recognize the difference between 1-2 points of skin being stimulated simultaneously (same time)

1. Person #1 rests their wrist on the table and closes their eyes

2. Using forceps, hold them tightly together and touch the skin of your partners index finger (pointer)

3. Move the forceps tips 1 mm apart

4. Repeat until your partner can feel both points

5. Measure (mm) the distance between the two points

This point is their two-point threshold- the point where two receptors are simultaneously being stimulated.

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Lab Report 30 Due TOMORROW

• Homework: Part A – Pg. 442-444 in book and notebook

• Classwork:– Finish Parts B/C/D

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Part D Sense of TemperatureObjective: To investigate the distribution of warm/cold receptors in your lab partner’s skin1. Prepare a 2.5 cm square, with .5 cm on each side, on your partner’s palm

2. Person #1 rests wrist on the table and closes their eyes

3. Heat the probe by placing it in a cup of hot water for approx 60 secs.

4. Wipe off probe and immediately place on a random square on your grid

Your partner will report when temperature is felt+ = felt o = not reported

5. Repeat on same grid with cold water

Switch Partners

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