Many people do not fully understand what hemorrhoids are, are hemorrhoids dangerous? Medically, hemorrhoids occur when the body has excessive dilation of the hemorrhoid plexus, anyone is at risk of this disease. In simpler terms, hemorrhoids are pathologies of a vascular system from arterioles, veins, and arteriovenous anastomosis to smooth muscle and connective tissue lined by the normal epithelium of the posterior duct. subject.