Question

The help of a well-labelled diagram describes the internal structure of the human heart.

Answer 1

Human heart has four chambers, two atria and two ventricles.
Atria:
Right atrium:

1. Two atria are separated by a septum. The right atrium receives deoxygenated blood from upper part of the body by superior vena cava and inferior vena cava collects blood from he lower part of the body. Coronary sinus brings blood from the heart muscles.
2. Eustachian valve guards the opening of inferior vena cava while the besian valve is present near the opening of coronary sinus.
3. A dperession called fossa ovails is present on the right side of interatrial septum.
4. Right atrium opens into right ventricle.

Left atrium:

1. Oxygeneated blood from lungs comes here via pulmonary veins.
2. Left atrium opens into left ventricle.

Ventricles:

1. Ventricles are the distributing chambers which are separated by interventricular septum.
2. Left ventricle has thickest wall as it pumps blood to all parts of the body.
3. In the opening of right atrium into right ventricle, tricuspid valve (three flaps) is present which controls the transportation of blood from right atrium to right ventricle. Similarly bicuspid valve is present in between left atrium and left venticle. It is also known as mitral valve.
4. These valves are attached to the ventricle by chorac tendineae, which prevents the back flow of blood.

From right ventricle: Pulmonary trunk carries deoxygenated blood to lungs for oxygenation.

From left ventricle: The aorta distributes oxygenated blood to all parts of the body. Pulmonary aorta and systematic aorta have three semilunar valves at the base which prevents back flow of blood.