A given receptor is described based on each classification criterion: receptor distribution, stimulus origin, and modality of stimulus. The eyes, for example, are because they are located in the head (receptor distribution); because they detect stimuli outside the body (stimulus origin); and because they detect light (modality of stimulus). In comparison, receptors that detect stretch of blood vessels are classified as because they are distributed throughout the body, because they detect stimuli within the body, and because they detect changes in distension of the organ wall.

Mr. j, age 42, is a construction worker in las vegas. he recently noticed that a mole on his face seemed to be getting larger and darker. at first he did not worry because he was in the sun a lot and assumed the change may have been caused by sunburn. after a month, not only was the mole larger and darker, but it appeared to be “bumpy.” his doctor diagnosed a malignant melanoma skin cancer following biopsy of the nevus. mr. j reports pain in his right shin that does not go away when he puts his feet up or sleeps. discussion questions 1. relate mr. j’s skin changes to the warning signs for malignant melanoma. (see malignant melanoma.) 2. discuss the normal progression of this malignancy. what is the significance of the bone pain that mr. j is experiencing? (see malignant melanoma.) 3. discuss the treatment available for this patient and the prognosis for recovery. (see malignant melanoma.)