1. : the final chemical messenger and "trigger" for muscle contraction. it binds to troponin. 2. : a neurotransmitter released at motor end plates by the axon terminals. 3. : it diffuses across the cell membrane resulting in depolarization. 4. : activates synaptic vesicles in axon terminals to fuse with plasma membrane of axon terminal. 5. : where the axon of a motor neuron connects with the muscle fibers. 6. : breaks down ach into its building blocks, rendering it inactive.

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.)