Q 1.Parasympathetic neuron stimulation of the pacemaker region of the heart_______________the heart rate 2.Adrenergic stimulation by ___________ usually secreted by the adrenal medulla, and by ___________________, secreted from sympathetic nerve endings, can produce both excitatory and inhibitory effects. 3. Unlike somatic motor neurons, autonomic motor neurons always involve ______ neurons in the efferent pathway. 4. The hypothalamus does not contain the control center for the homeostatic regulation of 5. What structure is the integrating center for thermoregulation? (Be specific)