EXPLORATION
Activity 1
Students will draw and label and identify the sensory receptors of the skin.
Students who have difficulties with fine motor skills may color and identify the sensory receptors.
This activity is from "The Anatomy Coloring Book". Authors, Wynn Kapit/Lawrence M. Elson
photo taken from "The Anatomy Coloring Book"/Authors: Kapit & Elson
1 - Epidermis
2 - Dermis
3 - Superficial Fascia
Sensory receptors make up a vast network of body-wide sensors that inform the central nervous system about the environment both within and outside the body. Such receptors are the terminals or endings of sensory nerve cells. in response to one of the variety of stimulations by energy states or forces (light waves, different degrees of mechanical contact, muscle stretch, certain chemical concentrations, etc.), a receptor will initiate an electrochemical reaction (impulse), which rapidly passes down the axon of a sensory nerve cell o the central nervous system. In response to this impulse, a quick reflex movement or a thoughtful, decisive move may be made, or possibly no reaction will be observed at al. here you are coloring those receptors found in or near the skin-receptors that make you aware of changes in the external environment (and which are constantly advising the central nervous system of the state of things even though you may not be aware of it).
Test these receptors on yourself as you color.
PAIN (a)
Free Nerve Endings (a)
One of two types of nerve endings that reach into the epidermis, free nerve endings are generally believed to fire in response to strong and painful stimulation. These endings are also found throughout the connective tissues of the body.
TOUCH (b)
Merkel's Discs (b)
Meissner's Corpuscles (b1)
Root Hair Plexuses (b2)
These receptors have a very low threshold of sensitivity and will therefore fir with the faintest touch, as you can test on yourself. The hair follicle is invested with free endings as well as the encapsulated discs of Merkel, which reaches up into the epidermal layers. Meissner's corpuscles consist of a core of nerve fibers and cells surrounded by other cell layers.
PRESSURE (c)
Pacinian Corpuscles (c)
The Pacinian corpuscle consists of a nerve ending surrounded by many layers of flattened cells. (Deformation of these capsules in the superficial fascia (and elsewhere) cause the nerve terminal to fire, resulting in an awareness of pressure above a certain threshold. They are also sensitive to vibration.
COLD (d)
Krause Corpuscles (d)
HEAT (e)
Ruffini Corpuscles (e)
These receptors of temperature are generally bulb-shaped and consist of nerve endings surrounded by several layers of flattened satellite cells. Experimental evidence for their cold/hot sensing function is scanty.
Activity 2
Students will view microscope slides of touch receptors. Vater-Pacini Corpuscle is located in deep layers of dermis in both hairy and glabrous skin (finger). It responds to vibration. Meissner's Plexus is a touch receptor which senses light touch. The teacher will facilitate student/teacher discussion of microscope slide using the flex camera. Students will draw, label and explain the function of each slide in their Science Journal.
Meissner's Corpuscles - (photo taken by r. pope-brown, using flex camera and microscope. slide from carolina biological supply)
Pacini's Corpuscles - (photo taken by r. pope-brown, using flex camera and microscope. slide from carolina biological supply)