The Human Circulatory System
The Human Circulatory System
Some Interesting Facts:
The circulatory system in the human body stretches 66,000 miles more than two and a half turns, the center of the Earth.
The heart beats 2.5 billion times during the life of a 75-year-old.
The heart expels 2 ounces of blood with each beat, 5 quarts of blood each minute, 220 million quarts in 70 years.
If the red blood cells from one person were to be stacked in the sky, they would reach 31,000 miles
Each red blood cell has 270,000,000 hemoglobin molecules; each hemoglobin molecule can carry four oxygen molecules.
Blood flow measurement is vital because it provides a window into the delivery of oxygen and nutrients to body organs and cells.
Structure of Human Heart
Location - The heart is the main pumping organ that pumps and also collects blood from the various parts of the body. It is located in the thoracic cavity between the two lungs. Thus, it is protected by the ribs. The size of the human heart is roughly the same as that of the size of a closed fist.
Coverings for protection - The heart is protected by the rib cage. The heart is covered by pericardium. There is a narrow space filled with a fluid called Pericardial fluid that performs the following functions:
Location - The heart is the main pumping organ that pumps and also collects blood from the various parts of the body. It is located in the thoracic cavity between the two lungs. Thus, it is protected by the ribs. The size of the human heart is roughly the same as that of the size of a closed fist.
Coverings for protection - The heart is protected by the rib cage. The heart is covered by pericardium. There is a narrow space filled with a fluid called Pericardial fluid that performs the following functions:
- Protection of heart from mechanical injury and shock
-It provides lubrication and thus reduces friction during a heartbeat
Chambers of the Heart - The human heart has four chambers. The upper two chambers are called auricles and the lower two chambers are called ventricles. Auricles are thin-walled whereas ventricles are thick-walled. Auricles pump blood to the ventricles and ventricles pump blood to all parts of the body. The partition that separates the two auricles is called the interatrial septum and the partition that separates the two ventricles is called the interventricular septum.
The major blood vessels that enter the heart -
1)Superior or Anterior Vena cava - It collects deoxygenated blood from the head, neck, chest, and arms and carries it to the right auricle.
2)Inferior or Posterior Vena cava - It collects deoxygenated blood from the abdomen and legs and carries it to the right auricle.
3)Pulmonary Vein - It carries oxygenated blood from the lungs to the left auricles.
The major blood vessels that leave the heart -
1)Pulmonary artery- it carries deoxygenated blood from the right ventricle to the lungs.
2) Aorta - It collects oxygenated blood from the left ventricle and distributes it to all parts of the body through its branches.
3)Coronary arteries - These are the first two major arteries that arise from the aorta. They supply blood to the heart to perform its functions.
Valves in the heart - Valves are the flaps or cups of tissues that prevent the backflow of blood. they regulate the unidirectional flow of blood.
There are four types of valves present in the heart -
1)Right atrioventricular valve or Tricuspid valve - This valve is located at the aperture between the right auricle and the right ventricle. It prevents the backflow of blood from the right ventricle to the right auricle.
2)Left atrioventricular valve or Bicuspid valve - This valve is located at the aperture between the left auricle and the left ventricle. It prevents the backflow of blood from the left ventricle to the left auricle.
3)Pulmonary semilunar valve - This valve is located at the opening of the right ventricle into the pulmonary artery. It prevents the backflow of blood from the pulmonary artery to the right ventricle.
4)Aortic semilunar valve - This valve is located at the opening of the aorta from the left ventricle. It prevents the backflow of blood from the aorta to the left ventricle.
The Pacemaker - There is a band of muscles in the corner of the right auricle called the sino-atrial node near the opening of the vena cava. There is a band of muscular tissue present in the lower side of the right atrium called the atrioventricular node. From the A-V node, branches arise called Bundle of His. These further give out branches to form a network throughout the walls of ventricles called Purkinje fibers.
Put on your thinking caps
Credits:
1) https://www.shutterstock.com
2) Together with Biology
3)Concise biology Class 10
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