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Orthostatic hypotension, also known as postural hypotension, [2] is a medical condition wherein a person's blood pressure drops when they are standing up (orthostasis) or sitting down. Primary orthostatic hypotension is also often referred to as neurogenic orthostatic hypotension. [ 3 ]
Orthostatic intolerance occurs in humans because standing upright is a fundamental stressor, so requires rapid and effective circulatory and neurologic compensations to maintain blood pressure, cerebral blood flow, and consciousness. When a human stands, about 750 ml of thoracic blood are abruptly translocated downward.
Postural orthostatic tachycardia syndrome (POTS) is a condition characterized by an abnormally large increase in heart rate upon sitting up or standing. [1] POTS is a disorder of the autonomic nervous system that can lead to a variety of symptoms, [10] including lightheadedness, brain fog, blurred vision, weakness, fatigue, headaches, heart palpitations, exercise intolerance, nausea ...
Multiple system atrophy (MSA) is a rare neurodegenerative disorder [1] characterized by tremors, slow movement, muscle rigidity, and postural instability (collectively known as parkinsonism), autonomic dysfunction and ataxia. This is caused by progressive degeneration of neurons in several parts of the brain including the basal ganglia ...
The baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure causes the heart rate to decrease. Decreased blood pressure decreases baroreflex activation and causes heart ...
Dysautonomia, autonomic failure, or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic. [5]
35094-2. Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" refers to the pressure in a brachial artery, where it is most commonly measured.
Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. [1] In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. [1] Heart rates above the resting rate may be normal (such as with exercise) or abnormal (such as with electrical problems within the heart).