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A slow heart rate of 60 or less beats per minute is defined as bradycardia. A fast heart rate of more than 100 beats per minute is defined as tachycardia. An arrhythmia is defined as one that is not physiological such as the lowered heart rate that a trained athlete may naturally have developed; the resting heart rates may be less than 60 bpm.
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.
In heart pacemaker cells, phase 0 depends on the activation of L-type calcium channels instead of the activation of voltage-gated fast sodium channels, which are responsible for initiating action potentials in contractile (non-pacemaker) cells. For this reason, the pacemaker action potential rising phase slope is more gradual than that of the ...
Activation of RyR2 causes it to open, releasing even more Ca 2+ into the cell, this release of calcium is called a calcium spark. This means that the initial flow of Ca 2+ into the cell, causes a larger release of Ca 2+ within the cell, therefore the process is called calcium induced calcium release (CICR). [8]
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 ...
The bundle of His (BH) [1]: 58 or His bundle (HB) [1]: 232 (/ h ɪ s / "hiss" [2]) is a collection of heart muscle cells specialized for electrical conduction.As part of the electrical conduction system of the heart, it transmits the electrical impulses from the atrioventricular node (located between the atria and the ventricles) to the point of the apex of the fascicular branches via the ...
The heart is a muscular organ found in humans and other animals. This organ pumps blood through the blood vessels. [1] Heart and blood vessels together make the circulatory system. [2] The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs. [3]
T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into the center of skeletal and cardiac muscle cells.With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potential into the cell, and also play an important role in regulating cellular calcium concentration.