Heart and Blood || Scientific FS
Heart and Blood
What is the heart?
The heart, one of the most vital organs of the human body, is a muscular organ with a circulatory system, which is responsible for pumping life-sustaining blood through the blood vessels spread throughout the body, by repeated, rhythmic contractions. From the movement it begins beating, until the moment it stops, the human heart works tirelessly.
Where in the human body?
The heart is located a little to the left of the middle of the chest, behind the breastbone, and is well protected by the rib cage. It is placed anterior to the vertebral column and posterior to the sternum or breastbone.
What is the size of a normal human heart?
A normal human heart is about the size of a clenched fist and it weighs approximately 250 o 300 grams in females and 300 to 350 grams in males. Right from birth, as the body develops, the heart grows at the same rate as the fist.
What is the internal structure of the heart?
The heart has three layers. The smooth, inside layer of the heart is called the endocardium and is in contact with the blood that the heart pumps. The middle layer is called the myocardium and is composed of cardiac muscle which contracts. The myocardium is surrounded by a fluid-filled sac called the pericardium. The outer layer is called the epicardium, or visceral pericardium since it is also the inner wall of the pericardium. The endocardium merges with the inner lining of blood vessels and covers the heart valves. The right side and the left side of the heart are separated by a thick wall of muscle called the septum.
How many parts does a human heart have?
A human heart has four chambers: the two upper chambers - the left atrium and the right atrium - are also called superior atria, and the two lower chambers - the right and left ventricles - also called inferior ventricles. Doctors commonly refer to the right atrium and right ventricle together as the right heart and to the left atrium and left ventricle as the left heart.
What do the left and right hearts do?
The right heart receives deoxygenated blood from all parts of the body and pumps it to the lungs, while the left heart receives oxygenated blood from the lungs and pumps it to the rest of the body.
What is blood?
Blood is a constantly circulating fluid providing the body with nutrition, oxygen, and waste removal. Blood is mostly liquid, with numerous cells and proteins suspended in it, making blood thicker than pure water.
How is blood carried to and from the heart?
Blood moves through many tubes called arteries and veins, which together are called blood vessels. These blood vessels are attached to the heart. Blood going towards the heart is carried through veins. blood going away from the heart is carried through arteries.
How does blood travel through the heart?
The pathway of blood through the human heart consists of a pulmonary circuit and a systemic circuit. Deoxygenated blood is oxygenated in the pulmonary circuit. Deoxygenated blood flows through the heart in one direction, entering through the superior vena cava (Heart's veins) into the right atrium. From here, it is pumped through the tricuspid valve into the right ventricle before being pumped out through the pulmonary arteries into the lungs. From the lungs, the oxygenated blood flows back toward the heart through the pulmonary veins to the left atrium. From here, it is pumped through the mitral valve into the left ventricle before leaving through the aortic valve to the aorta. in the systematic circuit, blood leaves the heart through the aortic valve to the aorta. in the systemic circuit, blood leaves the heart through the aorta, goes to all the organs of the body through the systematic arteries, and then returns to the heart through the systemic veins.
What is the function of the valves in the heart?
The four valves - tricuspid, pulmonary, mitral, and aortic - found in the human heart ensure that blood only goes one way, either in or out. They open up to let the blood move ahead, then they close quickly to keep the blood from flowing backward.
What is a heartbeat?
A heartbeat is the sound of the pumping of the heart, also called the Cardiac Cycle. The closing of the mitral and tricuspid valves causes the first part of the "lubb-dubb" sound made by the heart as it beats. The second part of the "lubb-dubb" is caused by the closure of the aortic and pulmonary valves. The average human heart beats 72 times per minute and takes less than 60 seconds to pump blood to every cell in the body. normally, with each beat, the right ventricle pumps the same amount of blood into the lungs that the left ventricle pumps out into the body.
How does the heart get its own supply of oxygenated blood?
The heart receives its own supply of oxygenated blood from coronary arteries. Two major coronary arteries branch off from the aorta near the point where the aorta and the left ventricle meet.
What is blood composed of?
Blood is composed of several types of cells, floating around in a fluid called plasma. The most important cells that compose blood are the Red Blood Cell (RBC), the White Blood Cell (WBC), and the Platelets. Plasma is a very relatively clear, yellow-tinted water (92+%), sugar, fat, protein, and salt solution. The average adult has a blood volume of roughly 5 liters.
What are Red Blood Cells?
RBCs are relatively large microscopic cells without nuclei. They are normally makeup 40-50% of the total blood volume. They contain haemoglobin and transport oxygen from the lungs to all the living tissues of the body and carry away carbon dioxide. in men, there is an average of 5200000 RBCs per cubic millimeter, whereas, in women, they are an average of 4600000.
What is Hemoglobin?
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cell of all vertebrates and makes up 95% of an RBC. It in the blood carries oxygen from the respiratory organs (lungs) to the rest of the body where it releases the oxygen to burn nutrients to provide energy to power the functions of the organism and collects the resultant carbon dioxide to bring it back to the respiratory organs to be dispensed from the organism.
What are WBCs?
WBCs, also called leukocytes, protect the body from infection; they attack and destroy foreign particles like dust, pollen, and viruses. They exist in variable numbers and types, but make up a very small part of the blood's volume. A drop of blood can contain anywhere from 7000 to 25000 white blood cells at a time. They are not limited to blood; they occur elsewhere in the body as well, most notably in the spleen, liver, and lymph glands.
What are Platelets?
Platelets, also called thrombocytes, are irregularly shaped, colorless bodies present in the blood. Their sticky surface lets them, along with other substances, form clots to stop bleeding to prevent blood loss. platelets flow freely in the blood in an inactive state; but when an injury is sustained, platelets become sticky to plug the injured area. The mineral calcium, vitamin K and a protein called fibrinogen help the platelets from a clot when the blood is exposed to air.
Where are the Various blood cells made?
The RBCs are produced continuously in our bone marrow from stem cells at a rate of about 2-3 million cells per second. The RBCs have a life span of about 120 days. Most WBCs are produced in our bone marrow from the same kind of stem cells that produce RBCs. Others are produced in the thymus gland, which is at the base of the neck.
Why do different people have different blood groups?
The differences in human blood are due to the presence or absence of certain protein molecules called antigens and antibodies. The most common type of grouping is the ABO grouping, according to which there are four kinds of blood groups: A, B, AB, or O. Another factor that plays an important role in the grouping of blood is a protein called the RH factor. If this is present, the particular blood type is called positive; if not, it is called negative.
The heart comprises less than 0.5 percent of total body weight.
Most of the time, arteries carry oxygenated blood and veins carry deoxygenated blood. But there are exceptions. The pulmonary arteries carry deoxygenated blood and the pulmonary veins carry oxygenated blood.
The Aorta is the largest artery in the body.
The red color of blood is primarily due to the oxygenated RBCs.
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