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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 heart is a muscular organ found in most animals. This organ pumps blood through the blood vessels of the circulatory system. [1] The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to the lungs. [2] In humans, the heart is approximately the size of a closed fist and is located ...
The circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. [ 1 ][ 2 ] It includes the cardiovascular system, or vascular system, that consists of the heart and blood vessels (from Greek kardia meaning heart, and from Latin vascula ...
The resting heart rate of a newborn can be 120 beats per minute (bpm) and this gradually decreases until maturity and then gradually increases again with age. The adult resting heart rate ranges from 60 to 100 bpm. Exercise and fitness levels, age and basal metabolic rate can all affect the heart rate. An athlete's heart rate can be lower than ...
Cardiac muscle. Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, the others being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall of the heart. The cardiac muscle (myocardium) forms a thick middle layer between the ...
The American Heart Association states the normal resting adult human heart rate is 60–100 bpm. An ultra-trained athlete would have a resting heart rate of 37–38 bpm. [3] Tachycardia is a high heart rate, defined as above 100 bpm at rest. [4] Bradycardia is a low heart rate, defined as below 60 bpm at rest.
The heart derives from embryonic mesodermal germ layer cells that differentiate after gastrulation into mesothelium, endothelium, and myocardium.Heart induction occurs in the anterior mesoderm during gastrulation through interactions with adjacent endoderm (both extra-embryonic and definitive) mediated primarily by endogenous inhibitors of WNT signaling such as DKK1.
See media help. The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. [1] It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, called systole. [1]