The adrenal medulla develops from neural tissue and secretes two hormones, epinephrine and norepinephrine. These two hormones are secreted in response to stimulation by sympathetic nerve, particularly during stressful situations. A lack of hormones from the adrenal medulla produces no significant effects.
Premature ventricular contractions (PVCs, PVC) are premature heartbeats originating from the ventricles of the heart. Premature ventricular contractions are premature because they occur before the regular heartbeat. The heart has four chambers. The upper two chambers are the atria, and the lower two chambers are the ventricles.
Primary Cause of Chickenpox. The primary cause of Chickenpox is the result: 1  of transmission of an infectious agent by another person by one or more of the following: saliva, air, cough, fecal-oral route, surfaces, blood, needles, blood transfusions, sexual contact, mother to fetus, etc.hickenpox: Related Medical Conditions. To research the causes of Chickenpox, consider researching the causes of these these diseases that may be similar, or associated with Chickenpox: 1  Varicella-zoster virus (VZV). 2  Shingles (or herpes zoster). 3  Red.