Heart Structure

The heart is a muscular organ, hollow, tetracameral, rhythmically pumping blood into the arteries which it receives through the veins. Although humans weigh about 300 grams and is the size of an adult fist. The heart makes a huge task, daily number of contractions are over 100,000 times and pumping over 7200 liters of blood. Which meets the heart, it is found that is constructed from two atria and two ventricles, completely separated by inter atrial and iterventricular septa. Each atrium ventricle that communicates with atrio-ventricular openings provided with valves that open only in a certain sense, to ventricle. Heart is made of lime concentric layers: endocardium, myocardium and epicardial. endocardium consists of a basal endothelium located in a membrane that is continuous with subendotelial layer composed of collagen fibers, reticulin fibers, elastic fibers, connective cells and numerous rare sensory nerve endings.

Myocardium consists of cardiac muscle fiber bundles oriented Circular atrial wall, and oblique-spiral fibers in the ventricles. In the heart wall. Outside celulelo attack, theire specialized cells in the generation and management of contraction impulse, they are excitoconductor nodal tissue. Epicardial is a thin membrane that covers connective epitelio-cardiac area and the visceral pericardium is the bag. Between foil pericardium is pericardial cavity with a liquid lama, which promotes sliding in time of hearts activity. Vasculature heart, extremely rich is provided by the two coronary arteries are detached from the aortic origin and are divided into branches that are not anastomosis between them.Obstruction of a coronary or its branches causes cardiac necrosis territory served.

Extrinsic innervation of the heart is achieved by sympathetic and parasympathetic autonomic fibers forming the cardiac plexus. Sympathetic fibers from cervical paravertebral ganglia and exercise effects on myocardial stimulation and coronary vasodilators. Parasympathetic nerve fibers from vague wich innerve predominant sinoatrial and atrioventricular nodes and the effect of reducing the activity of the heart.

Properties of heart muscle:

Myocardium which structurally is a striated muscle striated muscle has common properties, but also a number of characteristic properties.

-Owned Regularity heart to contract sequentially as a result of pulses generated by node contractions. These impulses are the result of metabolic changes that occur excitoconductor system.

-Conductivity is the property of myocardial tissue specil driving node where the contraction of the heart throughout the node.

-Excitability is owned myocardium to respond by contraction to appropriate stimuli.

-owned myocardial contractility is ment units to contract appropriately when stimulated. Myocardial contraction and relaxation is called diastole Sisto