Cardiovascular system

Car­dio­vas­cu­lar sys­tem in the close cir­cu­la­to­ry trans­port sys­tem. They trans­port res­pi­ra­to­ry gas­es and excre­to­ry prod­uct through the medi­um of blood to var­i­ous parts of the body.

It con­sist of blood pump­ing sta­tion ‘The heart’ and its cham­ber, the blood vessels.

The Heart

The human heart is a mus­cu­lo­tendi­nous organ which lies in the left upper part of chest cav­i­ty. The right bor­der is under­neath the right side of the Ster­num. The base of the heart is sit­u­at­ed below and the medi­al through the left nip­ple. 2/3 of the heart sit­u­at­ed on the left side and lies oblique­ly. The left bor­der of the heart is 9cm on the left of mid line. The heart is about 10 cm long and it weighs about 280 to 300 gram in male and 260 to 280 gram in female.

Struc­ture or lay­er of the heart

The heart con­sists of three layer: 

1. The out­er lay­er out­er­most lay­er is called peri­cardi­um. peri­cardi­um forms a bag like struc­tur­al called peri­car­dial sac. The peri­car­dial sac con­tain a flu­id called peri­car­dial flu­id which pre­vent fric­tion dur­ing each heartbeat.
2. The mid­dle lay­er is called myocardi­um. It is made up of car­diac mus­cles and fibroblast.
3. The inner­most lay­er is call endocardium.

Cham­ber of the heart

The heart is made up of four cham­ber. The two Cham­bers of right side is known as right Atri­um and right ven­tri­cle. The two Cham­ber of left side is known as left Atri­um and left ven­tri­cle. These four Cham­bers are formed by two Sep­ta inter atri­al sep­tum and inter ven­tric­u­lar septum.

Right Atri­um

It is above and to the right of the heart. It has thin walls with an appendage called the auri­cle. Supe­ri­or Vena cava brings the Co2 con­tained blood (deoxy­genat­ed blood) from upper part of the body where as infe­ri­or Vena cava brings the blood from low­er part of the body to the right atri­um. Besides these two open­ing there is an anoth­er open­ing of coro­nary sinus which brings the blood from coro­nary veins of the heart muscles.

Right Ven­tri­cle

This ven­tri­cle is present on the right side just below the right Atri­um. It has thick wall as com­pared to the right Atri­um but thin­ner then the wall of left ven­tri­cle. Right ven­tri­cle open in the pul­monary trunk. This trunk car­ries blood to the lungs for oxy­gena­tion. The pul­monary trunk divides into two branch­es, the right Pul­monary artery that pass­es to the right lung and the left Pul­monary artery that pass­es to the left lung for pul­monary cir­cu­la­tion. The pul­monary trunk has a semi-lunar valve with three curved semi­lu­nar cus­pid. This valve closed to pre­vent the back­flow of the blood into the right ven­tri­cle at the start of the ven­tric­u­lar dias­tole. There is a big open­ing between the right Atri­um and the right ven­tri­cle called the right artrio ven­tric­u­lar open­ing. This open­ing is guard­ed by a tri­cus­pid valve. This valve pre­vents the back of flow of blood into the right atri­um in the begin­ning of systole.

Left Atri­um

It is sit­u­at­ed not to the left as much as to the back of the heart. It has thin walls like that of the right Atri­um. There are four open­ing of four pul­monary veins to, on each side. These Pul­monary vein brings oxy­genat­ed blood to the left Atri­um for pass­ing the blood to the left ventricle. 

Left Ven­tri­cle

It is sit­u­at­ed on the ante­ri­or aspect of the left side of the heart. The apex of the heart is formed by the tip of the left ven­tri­cle. The wall of the left ven­tri­cle are three times thick­er than the right ven­tri­cle. It has to pump the blood all over the body which is named as sys­temic cir­cu­la­tion. The aor­ta is the biggest artery of the body starts from the left ven­tri­cle. Its open­ing like that of Pul­monary trunk is guard­ed by semi­lu­nar valve. This valve has three curved semi­lu­nar cus­pid, which pre­vent the back­flow of blood into the left ven­tri­cle in the begin­ning of ven­tric­u­lar dias­tole result­ing in the sec­ond sound of the heart. Left Atri­um opens into the left ven­tri­cle through an open­ing called left atri­oven­tric­u­lar open­ing gau­rd­ed by a bicus­pid or mitral valve. Bicus­pid valve Guards against the back­flow of blood into the left Atri­um at the begin­ning of sys­tole. some ten­dons aris­es from the low­er order of mitral valve, they are chor­dae­tend­i­nae which is attached to the pap­il­lary mus­cles of ven­tric­u­lar walls.