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Physiological shunts, occur due to the effect of gravity. The highest concentration of blood in the pulmonary circulation occurs in the bases of the pulmonary tree compared to the highest pressure of gas in the apexes of the lungs. Alveoli may not be ventilated in shallow breathing. Shunting may also occur in disease states:
Clinical death is the medical term for cessation of blood circulation and breathing, the two criteria necessary to sustain the lives of human beings and of many other organisms. [1] It occurs when the heart stops beating in a regular rhythm, a condition called cardiac arrest. The term is also sometimes used in resuscitation research.
A ventilation/perfusion scan, [96] also called a V/Q lung scan, is a type of medical imaging using scintigraphy and medical isotopes to evaluate the circulation of air and blood within a patient's lungs, [97] [98] in order to determine the ventilation/perfusion ratio. The ventilation part of the test looks at the ability of air to reach all ...
Mean blood pressure decreases as the circulating blood moves away from the heart through arteries and capillaries due to viscous losses of energy. Mean blood pressure drops over the whole circulation, although most of the fall occurs along the small arteries and arterioles . [ 35 ]
Shock is a medical emergency and requires urgent medical care. If shock is suspected, emergency help should be called immediately. While waiting for medical care, the individual should be, if safe, laid down (except in cases of suspected head or back injuries). The legs should be raised if possible, and the person should be kept warm.
Brain ischemia is insufficient blood flow to the brain, and can be acute or chronic. Acute ischemic stroke is a neurological emergency typically caused by a blood clot blocking blood flow in a vessel in the brain. [15] Chronic ischemia of the brain may result in a form of dementia called vascular dementia. [16]
"Medical bleeding" denotes hemorrhage as a result of an underlying medical condition (i.e. causes of bleeding that are not directly due to trauma). Blood can escape from blood vessels as a result of 3 basic patterns of injury: [citation needed] Intravascular changes — changes of the blood within vessels (e.g. ↑ blood pressure, ↓ clotting ...
The heart did not pump blood around, the heart's motion sucked blood in during diastole and the blood moved by the pulsation of the arteries themselves. Galen believed that the arterial blood was created by venous blood passing from the left ventricle to the right by passing through 'pores' in the interventricular septum, air passed from the ...