An organelle is a specialized cellular structure in eukaryotic cells analogous to an organ in the body.Organelles are discrete structures within the cell that perform a specialized function. Most are surrounded by internal membranes and can be seen in the light or the electron microscope.n organelle is a specialized cellular structure in eukaryotic cells analogous to an organ in the body.
irregular pulse or heart palpitations; chest pain; pale skin; sweating; What causes abnormal heart rhythms? A number of things may cause an abnormal heartbeat, including high blood pressure. Other common causes are: Coronary heart disease. This serious heart problem occurs when cholesterol and other deposits block the coronary arteries. Medications
1 Atrial fibrillation (AFib) is an irregular heartbeat (arrhythmia) often, but not always, resulting in a fast heart beat (greater than 100 bpm) at rest. 2  Causes of AFib are numerous; for example: 3  overactive thyroid,  alcohol use,