Heart

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Shape and size with humans

The shape of the heart resembles well cone big as a fist and a rounded off, whose point points to the left in front downward and somewhat. The heart sits with humans usually easily to the left transferred behind the breastbone (see further below under topography), in rare cases to the right transferred (the so-called Dextrokardie - Rechtsherzigkeit), usually with Situs inversus (mirror-wrong organ arrangement).

The healthy heart weighs about 0.5% of the body weight and on the average between 300 and 350 g, whereby it reacts during durable load rather with (low-risk) the enlargement of heart muscle cells already existing - starting from approx. 500 g, the critical heart weight in such a way specified, the risk of a lack supply of the heart with oxygen, increased now, increases, since the supplying Koronararterien along-grows not equally.

Basic structure

The heart of the mammals consists of two parts.

• The right heart half, which pumps the blood by the cycle of the lung (small cycle).
• The left heart half, which carries the blood by the remaining body (large cycle).

Since the total container resistance of the body cycle is approximately five times larger than that of the lung cycle must perform, the left Herzkammer (see below) an accordingly larger Druckarbeit and therefore a clearly stronger wall thickness exhibits than the rights. The filling and impact volume of both Herzkammern are however alike.

Structure

Wall layers

The heart lies behind the breastbone in the thorax in a bindegewebigen heart bag (Perikard, Pericardium fibrosum), which encloses the heart completely. The internal layer of the heart bag (Pericardium serosum) strikes at the outlet of the large blood vessels (see below) into the Epikard over, which rests upon directly the heart. Between Perikard and Epikard lies then a Spaltraum filled with liquid, which makes possible friction-poor shifts hearts in the heart bag.

These complicated conditions become more descriptive, if one understands oneself the heart bag as a ballon locked filled with air and. The own hand closed to the fist represents the heart. If one imprints the ballon with the fist so far that she is completely enclosed by the balloon, then a layer of the ballon of the fist (the "“heart"”) fits directly. This layer, which corresponds to the Epikard, changes at the transition to the arm to an outside layer. This outside layer corresponds to the Perikard. Between both is an area filled with air, which is comparable to the Spaltraum filled with liquid of the heart bag.

Under the Epikard is a fat layer, in which the heart wreath/ring containers (see below) run. The thick muscle layer (myocardium) consists of specialized muscle tissue, which occurs only in the heart. The interiors are lined by the Endokard, which forms also the Herzklappen (see below).

Area and containers

Right and left heart half consist in each case of a chamber (ventricle) and a forecourt (atrium). These areas are separated by the heart septum. This becomes into the forecourt septum (septum interatriale) and the Kammerscheidewand (septum interventriculare) partitions.

The blood can flow in the heart areas only into a direction, since between the forecourts and chambers and the containers following to the chambers Herzklappen are, which work like valves. In right forecourt the upper and lower Hohlvene (Vena cava superior et inferior) flows. They supply the oxygen-poor (venous) blood from the large cycle to the heart. Between right forecourt and right chamber is the Trikuspidalklappe, which prevents a current reversal of the blood with the chamber contraction (Systole, see below) like a valve into the forecourt. It possesses three portions, which are fastened to the chamber musculature like sails over chord threads (therefore it also sail flap). Over a common trunk (Truncus pulmonalis) the two Lungenarterien leave the right chamber. Also between chamber and Lungenarterien is a Herzklappe, the Pulmonalklappe. This kind of the flaps is called because of its form also pocket flap. The Lungenarterien supplies the oxygen-poor blood to the lung cycle.

By usually four Lungenvenen the oxygen-rich (arterial) blood from the lung cycle flows to the left forecourt. From here it arrives over a further sail flap, the Mitralklappe at the left chamber. The Ausstrom takes place over the Aorta, which possesses like the Lungenarterie a pocket flap (Aortenklappe).

Note: Arterien transport the blood from the heart to the organs, Venen from the organs to the heart. Arterien of the body cycle lead oxygen-rich (arterial) blood, during Arterien of the lung cycle oxygen-poor (venous) blood lead. Turned around the blood in the Venen of the body cycle oxygen-poor (venously ), that the Lungenvenen oxygen-rich (arterially).

While a heart cycle fill first the forecourts, while the chambers eject the blood at the same time into the Arterien. If the chamber musculature relaxes, the sail flaps open by the decrease of pressure in the chamber and the blood flows in from the forecourts. This is supported by pulling the forecourts (Vorhofsystole together). The Kammersystole follows: the chamber musculature pulls, the pressure rises, the sail flaps together closes and the blood can only by the pocket flaps opened now into the Arterien leak out. A return flow of the blood from the Arterien during the relaxation phase (Diastole) is prevented by the conclusion of the pocket flaps. The direction of flow is determined thus alone by the flaps.

All four flaps of the heart are approximately in one level, the valve level, and are together hung up at a Bindegewebsplatte, the heart skeleton.

Topography with humans

The heart lies within the heart bag (Perikard) in the Mediastinum: Laterally border separately by parietale and viszerale Pleura the left and right lung on the heart. Down mount the heart the Zwerchfell, which grew together with the heart bag. Up the bronchial tube (trachea) divides into the two main bronchi (Bifurcatio tracheae), whose is crossed left by the aortic arch. Behind the left forecourt the esophagus lies in direct contact. Before the heart the breastbone (Sternum) is, in the upper range lies it before the outgoing large containers. Between breastbone and heart the thymus lies.

The heart lies thus practically directly behind the front body wall at height second to fifth rib. The heart basis above hands to the right about two centimeters out over right edge of breastbone. Down the heart point approaches scarcely to a meant senkrechte line, which runs by the center of the left (link Medioklavikularlinie).

Heart wreath/ring containers

From the initial part of the Aorta the heart wreath/ring containers (Koronararterien) rise. They supply the heart muscle with blood. The oxygen-poor blood from the heart muscle is led by the Herzvenen into the sine coronarius, which flows directly in right forecourt.

There is a left and a right Koronararterie:

• Link Koronararterie (Arteria coronaria sinistra, coronary a'rtery, if LCA l'eft) for the heart front
  • Main trunk
    • R'amus interventricularis anterior (RIVA, left anterior d'escending, LOD)
    • R'amus circumflex'us (RCX)
• Right Koronararterie (Arteria coronaria dextra, r'ight coronary a'rtery, RCA), which at the back plate into the Ramus interventricularis posterior changes, before it delivers it however still the A. marginalis more dexter, which right edge of heart supplies.
• Koronarvenen: the Vena runs in front cardiaca/cordis interventricularis anterior in the Sulcus interventricularis with the R. interventricularis anterior, which on height of splitting the A. coronaria sin. into its two Rami into V. cardiaca/cordis magna changes, which become for their part the sine coronarius. The sine coronarius takes up V. from the rear side cardiaca/cordis media and from the right edge of heart V. cardiaca/cordis parva.