Question

Explain the internal structure of heart?

Answer 1

The heart is a cone shaped hollow muscular organ. It lies in the thoracic cavity, just behind the breastbone (sternum) in between the lungs. It tips slightly towards the left hand side of the body.
The human heart weighs less than a pound (about 300 grams) and is roughly the size of an adult fist.
Structure of Heart:
The heart is a muscular cone-shaped organ about the size of a clenched fist of the same person. It is located in the upper body (chest area) between the lungs, and with its pointed end (called the apex) downwards, forwards, and pointing towards the left. The heart is a pump consisting of four chambers. It is vertically divided into two halves (left and right) by a septum. Each half is further divided into upper and lower halves, which communicates through atrio-ventricular valves. The two upper chambers are called atria (singular-atrium) and the two lower chambers are called ventricles.

Answer 2

Internal Structure of the Heart

Written by Marie-Luise Blue
The heart is a strong muscular pump that circulates and pumps about 2,000 gallons of blood each day and contracts and expands about 100,000 times per day. The normal heart is only as big as an average clenched fist and sits behind the breast bone, or sternum, slightly to the left in between the lungs. Large blood vessels leave and enter the heart and help to keep it in position. The internal structure of the heart consists of four hollow spaces, or chambers, divided by a tissue wall, called the cardiac septum. The flow of blood through the heart is regulated by four valves.


Cardiac Septum
A muscular tissue, the cardiac septum, divides the heart into a right and left side. Each side of the heart has an upper chamber or atrium, and a larger, lower chamber, or ventricle. The two sides of the heart have different functions, but they work together to shuttle the blood to all parts of the body.
Chambers
The right atrium is a thin-walled chamber that receives oxygen-poor, or deoxygenated, blood from the upper and lower parts of the body. It also receives deoxygenated blood from the muscular walls of the heart. The right ventricle fills with the deoxygenated blood from the right atrium and pushes the blood into the pulmonary arteries, which lead into the lungs. The blood is oxygenated in the lungs. The left atrium is also a thin-walled chamber that receives oxygenated blood from the lungs by means of four pulmonary veins. The left ventricle has a very thick muscular wall. When this ventricle contracts, oxygenated blood is forced through the aorta and its artery branches to all parts of the body.
Valves
The heart has four valves that open to let the blood flow when the heart contracts. Each valve has a set of flaps, called cusps or leaflets. The valves allow the blood to flow in only one direction and healthy valves close tightly to stop the blood from flowing backwards. A stethoscope can detect the sound of the heart valves opening and closing. The tricuspid valve is located between the right atrium and the right ventricle and the pulmonary valve on the right ventricle regulates the opening to the pulmonary artery. The mitral valve is situated between the left atrium and the left ventricle, while the aortic valve on the left ventricle controls the opening to the aorta.
Pacemaker
The rate at which the heart beats is controlled by electrical impulses mediated by the involuntary, or autonomic, nervous system. One nerve, coming from the brain, speeds up the heart beat, while another slows it down. The nerves terminate in a group of cells, located in the wall of the right atrium, called the sinus node or pacemaker.