Essay on Heart and Vena Cava

Submitted By blob1234
Words: 1434
Pages: 6

The Cardiovascular system:

The heart is a muscular pump that powers blood all around the human body and this is done by a method of blood vessels such as the arteries, capillaries and veins.
In the blood there is dissolved oxygen that is taken to the human body cells and also gets rid of the waste products of the respiration which is water and carbon dioxide. Blood also gives heat all around the human body, hormones, nutrients, salts, urea and also enzymes.

A heart of an adult is placed in the thoracic cavity which is between the lungs so it is safe and protected by the rib cage. Also, an adult’s heart is as big as a fist. Moreover, the heart is enclosed by the hard pericardium membrane that has a thin show of fluid to stop rubbing from taking place.
The heart in the human body is a double pump that each of its sides lays of a muscular higher area which is the atrium and the low area is the ventricle. The left side of the heart pumps oxygenated blood from the lungs to the human body and the right side of the heart pumps deoxygenated blood from the veins to the lungs for oxygen. Both of the sides are set-apart by a septum.
The circulation of the heart is called a double circulation because the blood passes twice direct into the heart in many one cycle.

The outcomes in the cardiac cycle can be represented in levels as the following: Both of the atria undertake, making the blood under pressure in the ventricles. The ventricles are bell-shaped with blood and the raised pressure makes the atrio-ventricular valves close and this makes the first heart sound. Also, the muscles that are in the ventricle walls start to undertake and the force on the blood inside increases and make the semi-lunar valves open in the aorta and also the pulmonary artery. Blood is forced into aorta which is the left side and pulmonary artery which is the right side by the ventricular systole. And these arteries have elastic walls that start to get bigger. The muscle begins to relax when the blood goes from the ventricles. Moreover, for a second the blood falls back that catches the sacks of the semi-lunar that forms them to shut and this makes the second heart sound. Atrio-ventricular valves get forced open with blood when the ventricles in diastole, that has been filled the atria. Once 70% of the ventricles are full then the atria undertake to force the left over blood quickly and then the next cycle starts.

Heart rate is the number of beats that are counted in one minute and stroke volume is the volume of the blood that is forced out of the heart in one beat.
Cardiac output is the amount of blood that is strained from the heart in only one minute. To be able to calculate the heart rate and stroke volume, the amount of blood forced from the left ventricle in only one beat and the amount of beats in one minute would have to be known. The stroke volume has 70cm3 and also a heart rate that is between 60-80 beats per minute of an average individual. However, people who train often have a high stroke volume and a low heart rate.

The power blood brings on the blood vessels wall that it passes through is recognised as blood pressure. Blood pressure can be measured by using specific equipment that is called the sphygmomanometer and it is sometimes shortened to 'sphygmo'. When the ventricles contract the systolic blood pressure reacts to the force of the blood. In the blood vessels the blood pressure is the highest as it is nearest to the heart such as the aorta and the large arteries. Blood pressure can fall quickly as the blood gets strained through the arteries and the arterioles that are medium sized, because these muscular vessels have good resistivity. Moreover, blood pressure is very low in the capillaries and in the veins blood has to be aided back to the heart and this is aided by a muscle pump. In the limbs the veins are placed between muscle groups and because they have more thin walls than the arteries do, and