symptoms of heart and blood vessel disorders
heart and blood vessel disorders
Dizziness or Light Headedness When Standing Up
Dizziness or light-headedness when standing up occurs as a result of abnormal blood pressure regulation. Normally, when people stand, gravity causes blood to pool in the veins of the legs and trunk. This pooling lowers the blood pressure and the amount of blood the heart pumps to the brain. Low blood flow to the brain causes the dizziness and other symptoms. To compensate, the nervous system quickly increases the heart rate and constricts blood vessels, which rapidly returns blood pressure to normal before symptoms can develop. The part of the nervous system responsible for this compensation is the Overview of the Autonomic Nervous System . Many disorders can cause problems with blood pressure regulation and lead to dizziness when standing up. Categories of causes include Malfunction of the autonomic nervous system due to disorders or drugs Decreased ability of the heart to pump blood Decreased blood volume (hypovolemia) Faulty hormonal responses Causes differ depending on whether symptoms are new or have been present for some time. The most common causes ofnewdizziness when standing up include Decreased blood volume (as may result from dehydration or blood loss) Drugs Prolonged bed rest An underactive adrenal gland (adrenal insufficiency) The most common causes of dizziness when standing up that has been present for along time (chronic)include Age-related changes in blood pressure regulation Drugs Malfunction of the autonomic nervous system 