A sense of impending doom is a medical symptom that consists of an intense feeling that something life-threatening or tragic is about to occur, despite no apparent danger. Causes can be either psychological or physiological. Psychological causes can include an anxiety disorder (e.g., panic disorder), depression, or bipolar disorder. A sense of impending doom often precedes or accompanies a panic attack. Physiological causes could include a pheochromocytoma, heart attack, blood transfusion, anaphylaxis, or use of some psychoactive substances. The feeling can also be a transient side effect of adenosine administration, likely due to its activation of adenosine receptors. Due to adenosine's extremely short half-life, this effect is typically short-lived. A sense of impending doom can also present itself as a postoperative complication encountered after surgery.
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Pheochromocytoma in the context of Adenocarcinoma
Adenocarcinoma (AC) is a type of cancer made of cells from glands. They can occur in many parts of the body. Adenocarcinomas are part of the larger grouping of carcinomas, but are also sometimes called by more precise terms omitting the word, where these exist. Adenocarcinomas are defined as neoplasia of epithelial tissue that has glandular origin or glandular characteristics. Thus invasive ductal carcinoma, the most common form of breast cancer, is adenocarcinoma but does not use the term in its name. However, esophageal adenocarcinoma does, to distinguish it from the other common type of esophageal cancer, esophageal squamous cell carcinoma. Several of the most common forms of cancer are adenocarcinomas, and the various sorts of adenocarcinoma vary greatly in all their aspects, so that few useful generalizations can be made about them.
In the most specific usage, the glandular origin or traits are exocrine; endocrine gland tumors, such as a VIPoma, an insulinoma, or a pheochromocytoma, are typically not referred to as adenocarcinomas but rather are often called neuroendocrine tumors. Epithelial tissue sometimes includes, but is not limited to, the surface layer of skin, glands, and a variety of other tissue that lines the cavities and organs of the body. Epithelial tissue can be derived embryologically from any of the germ layers (ectoderm, endoderm, or mesoderm). To be classified as adenocarcinoma, the cells do not necessarily need to be part of a gland, as long as they have secretory properties. Adenocarcinoma is the malignant counterpart to adenoma, which is the benign form of such tumors. Sometimes adenomas transform into adenocarcinomas, but most do not.
Pheochromocytoma in the context of Sympathoadrenal system
The sympathoadrenal system is a physiological connection between the sympathetic nervous system and the adrenal medulla and is crucial in an organism's physiological response to outside stimuli. When the body receives sensory information, the sympathetic nervous system sends a signal to preganglionic nerve fibers, which activate the adrenal medulla through acetylcholine. Once activated, norepinephrine and epinephrine are released directly into the blood by adrenomedullary cells where they act as the bodily mechanism for "fight-or-flight" responses. Because of this, the sympathoadrenal system plays a large role in maintaining glucose levels, sodium levels, blood pressure, and various other metabolic pathways that couple with bodily responses to the environment. During numerous diseased states, such as hypoglycemia or even stress, the body's metabolic processes are skewed. The sympathoadrenal system works to return the body to homeostasis through the activation or inactivation of the adrenal gland. However, more severe disorders of the sympathoadrenal system such as pheochromocytoma (a tumor on the adrenal medulla) can affect the body's ability to maintain a homeostatic state. In these cases, curative agents such as adrenergic agonists and antagonists are used to modify epinephrine and norepinephrine levels released by the adrenal medulla.