This is a muscular organ comprised of Cardiac muscle that provides blood throughout the body.
Cardiac muscle is an involuntary muscle that contracts on its own.
The heart beats (contracts) around 70 times a minute.
The Heart is made up of 4 Chambers or Cavities
1.) Right Atrium
2.) Right Ventricle
3.) Left Atrium
4.) Right Atrium
Heart Contraction or Pulmonary Circulation
Step 1: Blood (without oxygen) returns to the heart and enters the Right Atrium
Step 2: Blood from the Right Atrium is pushed into the Right Ventricle.
Step 3: Blood from the Right Ventricle is pushed into the lungs where it is oxygenated.
Step 4: Blood returns from the Lungs (with oxygen) and enters the Left Atrium.
Step 5: Blood from the Left Atrium is pushed into the Left Ventricle.
Step 6: Blood from the Left Ventricle is pushed out of the heart and around the entire body.
This entire system is referred to as Pulmonary Circulation.
4 major Valves of the heart
1.) Tricuspid Valve
2.) Pulmonary Valve
3.) Mitral Valve
4.) Aortic Valve
Blood flow with valve involvement
The blood enters the right atrium and enters the right ventricle through a valve called the tricuspid valve.
It then is pumped from the right ventricle to the pulmonary arteries through the pulmonary valve.
Within the – carbon dioxide is released and oxygen enters the blood stream.
The blood is pumped back to the heart by the pulmonary veins and enters the left atrium.
It then enters the left ventricle via the mitral valve.
Blood leaves the heart through the last valve via the aortic valve and is pumped throughout the body.
Coronary circulation is the vessels that supply the heart itself with blood
When blood leaves the heart it passes through arteries.
From arteries blood enters arterioles and finally into capillaries.
These are the thinner aspects of the blood vessels. Capillaries allow blood or nutrients to get into the tissues and cells.
Carbon dioxide and other wastes are collected into venules which flows into veins.
The blood is then returned to the heart.
The heart itself is enclosed in a sac referred to as the Pericardium
Two aspects of the pericardium include:
1.) Fibrous pericardium
2.) Serous pericardium
How does the heart beat at a constant rate?
This answer lies within the specific cells of the heart.
There is a specific area in heart called the sinoatrial node (SA node) that regulate heartbeat.
The cells involved are called pacemaker cells.
These cells send an electrical pulse throughout the heart that tells it to contract.
The impulse travels the following route:
First, the impulse begins in the SA node
Second, It travels from the SA node to the right and left atria within milliseconds.
Then the impulse travels to the AV node
Next to the Bundle of His
Then to the Right and Left bundle branches
Finally to the Purkinje fibers to the Right and Left ventricles.
If the SA node has lost function either temporarily or permanently then cells from the atrioventricualar node (AV node) will then become the â€œpacemakerâ€ cells.
Examination of the Heart or its Electrical System
Valve problems of the heart
Other Disorders of the Heart
Genetic problems with the heart