What actually is our heart? It is said to be a dark cone-shaped muscular organ found in the thoracic cavity protected by our ribs. It is also said that the heart is about the size of our fist, but I don't know if that's true.
Our human heart is one superb design! It has four chambers. They are the left and right atrium, and the left and right ventricle. It's pretty much the same as in what was taught in form 3. There are valves in the heart too, to prevent the black flow of blood.
Our heart, is pretty similar to a car engine. It's the most important and vital part of all. WIthout it, we're useless, quite similar to a car if the engine's gone. There are two nodes in the heart.
At the right atrium wall, near the entrance of the vena cave, there are a group of specialized cells called the sino-atrial node, short form SA node. This is the first node found in the heart.This node acts like a pacemaker, which initiates the heart beat. This SA node generates a wave of excitatory impluses to the two atria, causing them to contract simultaneously. Blood is then forced from the atria to the ventricles.
The second node, found in our heart, is the atrio-ventricular node, short form AV node. This node is located at the base of the right atrium. The impulses created by the AV node are conducted by specialized muscle fibres, called the Purkinje fibres, to the ventricular walls. What an odd name, hor? This causes the both ventricles to pump the blood out of the heart.
The whole process of the contraction, or also known as systole, and relaxation, also known as diastole, of the heart all occurs in a single heartbeat. The heart beats pretty fast, eh? This whole process can be called as a cardiac cycle. An average human heart pumps at about 72 heartbeats per minute. That's 1.2 beats per second.
Our heart is a really magnificent masterpiece created in the image of God. God has planned every single detail perfectly. He pictured the heart without a single flaw. Thank You GOD!