Give me a note on heart for science class 10 NCERT
If u give then 35 points are yours ; )
Answers
Answer:
The heart is a muscular organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to the lungs.
Structure-
The human heart is about the size of a human fist and is divided into four chambers, namely two ventricles and two atria. The ventricles are the chambers that pump blood and atrium are the chambers that receive blood. Among which both right atrium and ventricle make up the “right heart,” and the left atrium and ventricle make up the “left heart.” The structure of the heart also houses the biggest artery in the body – the aorta.
Working-
The right atrium receives blood from the upper and lower body through the superior vena cava and the inferior vena cava, respectively, and from the heart muscle itself through the coronary sinus. The right atrium is the larger of the two atria, having very thin walls. The right atrium opens into the right ventricle through the right atrioventricular valve(tricuspid), which only allows the blood to flow from the atria into the ventricle, but not in the reverse direction.
The right ventricle pumps the blood to the lungs to be reoxygenated.
The left atrium receives blood from the lungs via the four pulmonary veins. It is smaller than the right atrium but has thicker walls. The valve between the left atrium and the left ventricle, the left atrioventricular valve(bicuspid), is smaller than the tricuspid. It opens into the left ventricle and again is a one-way valve.
The left ventricle pumps the blood throughout the body through the aorta, which is the largest artery in the body. The walls of the left ventricle are the thickest among all the chambers.
The Heart is the muscular pumping organ that pushes the blood around the body.
Blood transports carbon dioxide to the lungs for oxygen from the cells for removal and carries oxygen from the lungs to the heart and heart pump the blood to all the cells of the body.
Heart has different chambers such as right atrium, left atrium, right ventricle, left ventricle to prevent the mixing of oxygenated blood and carbon dioxide rich blood.
The thin walled upper chamber, left atrium, relaxes and oxygenated blood enters it.
Left atrium then contracts and the next chamber left ventricle, expands and thus blood enters it.
When the left ventricle contracts the blood is pumped out to all the cells of the body.
Deoxygenated blood from the body reaches the right upper chamber, right atrium when it expands.
As the right atrium contacts, the lower chamber, right ventricle, dilates.
Separation of right and left side of heart allows efficient supply of oxygen to the body and useful for animals that have high energy needs to maintain their body temperature.
In some animals, body temperature depends on the temperature in the environment and thus they do not use energy to maintain body temperature.
Amphibians and reptiles have three chambered heart and allows some mixing of oxygen and deoxygenated blood.
Fishes have two chambered heart and the blood is pumped to the gills for oxygenation and transported directly to all the cells of the body.
When blood goes through the heart twice during each cycle, the process is called as double circulation.
In fish, blood goes only once through the heart and thus fish shows single circulation.