The human heart is an organ that pumps blood all through the physique by the circulatory system.
In people, the heart is roughly the measurement of a giant fist and weighs between 280-340 grams in males and 230-280 grams in females.
The human heart has 4 chambers; two higher chambers (auricle) and two decrease chambers (ventricles).
The correct atrium and proper ventricle collectively make up the “proper heart”, and the left atrium and left ventricle make up the “left heart”. A muscular wall referred to as the septum divides the heart into two areas.
The outer wall of the heart consists of three layers. The outermost wall layer or epicardium is the inside wall of the pericardium.
The center layer, or myocardium, comprises the contracting muscle. The inside layer, or endocardium, is the overlaying that comes into contact with blood.
The tricuspid valve and mitral valve type the atrioventricular (AV) valves that join the atria and ventricles.
CIRCULATION OF BLOOD
The heart circulates blood in two methods: the pulmonary circuit and the systemic circuit. In the pulmonary circuit, deoxygenated blood leaves the proper ventricle of the heart by way of the pulmonary artery and goes to the lungs, then returns to the left atrium of the heart by way of the pulmonary vein as oxygenated blood.
In the systemic circuit, oxygenated blood leaves the physique by way of the left ventricle and passes by the aorta (predominant artery) and from there into the arteries and capillaries, the place it provides oxygen to the physique’s tissues.
The deoxygenated blood returns by the veins to the vena cava (predominant veins) and re-enters the proper atrium of the heart.
The heart is additionally a muscle, so it additionally wants a contemporary provide of oxygen and vitamins.
The heart comprises electrical cells, which, along with contraction, produce a heartbeat.
STAGES OF HEART CONTRACTION
A wholesome heart contraction happens in 5 phases. In the first stage (early diastole), the heart relaxes. The atrium then contracts to push blood into the ventricle. Then the ventricles start to contract with out altering quantity.
Then the ventricles proceed to contract whereas they’re empty. Lastly, the ventricles cease contracting and chill out. The loop repeats like this.
Valves hold blood flowing in a single path by the heart, stopping backflow.