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Ischemia: A decrease or restriction of circulating blood flow to a region of the brain which deprives neurons of the necessary substrates (primarily glucose); represents 80% of all strokes. A thrombus or embolus plugs an artery so there is a reduction or cessation of blood flow.
Cardiac physiology or heart function is the study of healthy, unimpaired function of the heart: involving blood flow; myocardium structure; the electrical conduction system of the heart; the cardiac cycle and cardiac output and how these interact and depend on one another.
The lumped parameter model consists in a system of ordinary differential equations that adhere to the principles of conservation of mass and momentum balance. The model is obtained exploiting the electrical analogy where the current represents the blood flow, the voltage represents the pressure difference, the electric resistance plays the role of the vascular resistance (determined by the ...
The blood pressure in the circulation is principally due to the pumping action of the heart. [32] The pumping action of the heart generates pulsatile blood flow, which is conducted into the arteries, across the micro-circulation and eventually, back via the venous system to the heart.
This is typically secondary to stroke, injury, or cardiac arrest due to heart attack. Most ischemic neurons that die do so due to the activation of chemicals produced during and after ischemia. [2] The ischemic cascade usually goes on for two to three hours but can last for days, even after normal blood flow returns. [3]
In a healthy heart all activities and rests during each individual cardiac cycle, or heartbeat, are initiated and orchestrated by signals of the heart's electrical conduction system, which is the "wiring" of the heart that carries electrical impulses throughout the body of cardiomyocytes, the specialized muscle cells of the heart.
A healthy heart has four chambers, each separated by valves that open and close to control blood flow between the chambers. When the heart beats, oxygen-poor blood enters the right atrium. The blood then flows into the right ventricle, where it pumps into the pulmonary artery to travel to the lungs for oxygen. Oxygen-rich blood returns to the ...
In diagrams illustrating the Frank–Starling law of the heart, the y-axis often describes the stroke volume, stroke work, or cardiac output. The x-axis often describes end-diastolic volume , right atrial pressure , or pulmonary capillary wedge pressure .