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From Earths surface to the top of the stratosphere (50 km) is just under 1% of Earth's radius. The mesosphere (/ ˈ m ɛ s ə s f ɪər, ˈ m ɛ z-, ˈ m iː s ə-,-z ə-/; [1] from Ancient Greek μέσος (mésos) 'middle' and -sphere) is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere.
Heart failure is caused by chronic oxygen deprivation due to reduced blood flow, which weakens the heart over time. Arrhythmias are caused by inadequate blood supply to the heart that interferes with the heart's electric impulse. The coronary arteries can constrict as a response to various stimuli, mostly chemical. This is known as a coronary ...
This is a list of arteries of the human body. The aorta; The arteries of the head and neck. The common carotid artery. The external carotid artery; The triangles of the neck; The internal carotid artery; The arteries of the brain; The arteries of the upper extremity The subclavian artery; The axilla. The axillary artery; The brachial artery ...
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Real-time MRI of the human heart The human heart is in the middle of the thorax, with its apex pointing to the left. [15] The human heart is situated in the mediastinum, at the level of thoracic vertebrae T5–T8. A double-membraned sac called the pericardium surrounds the heart and attaches to the mediastinum. [16]
The right heart pumps deoxygenated blood to the lungs in the pulmonary circulation. In the human heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle. The right atrium is the upper ...
While the patient is exercising, images of the heart in motion are generated. [34] Ischemia can be detected by visualizing abnormalities in the movement of the heart and the thickness of the heart wall during exercise. [34] Some people may be unable to exercise in order to achieve a sufficient heart rate for a useful test.
The heart is a muscular organ situated in the mediastinum.It consists of four chambers, four valves, two main arteries (the coronary arteries), and the conduction system. The left and right sides of the heart have different functions: the right side receives de-oxygenated blood through the superior and inferior venae cavae and pumps blood to the lungs through the pulmonary artery, and the left ...