The heart is a myogenic muscular organ found in all animals with a circulatory system (including all vertebrates), that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions. The term cardiac (as in cardiology) means "related to the heart" and comes from the Greek kardia, for "heart".
The vertebrate heart is composed of cardiac muscle, which is an involuntary striated muscle tissue found only in this organ, and connective tissue. The average human heart, beating at 72 beats per minute, will beat approximately 2.5 billion times during an average 66 year lifespan. It weighs approximately 250 to 300 grams (9 to 11 oz) in females and 300 to 350 grams (11 to 12 oz) in males.
Human Heart
The human heart has a mass of between 250 and 350 grams and is about the size of a fist. It is located anterior to the vertebral column and posterior to the sternum.
It is enclosed in a double-walled sac called the pericardium. The superficial part of this sac is called the fibrous pericardium. This sac protects the heart, anchors its surrounding structures, and prevents overfilling of the heart with blood.
The outer wall of the human heart is composed of three layers. The outer layer is called the epicardium, or visceral pericardium since it is also the inner wall of the pericardium. The middle layer is called the myocardium and is composed of muscle which contracts. The inner layer is called the endocardium and is in contact with the blood that the heart pumps. Also, it merges with the inner lining (endothelium) of blood vessels and covers heart valves.
The human heart has four chambers, two superior atria and two inferior ventricles. The atria are the receiving chambers and the ventricles are the discharging chambers. The pathway of blood through the human heart consists of a pulmonary circuit and a systemic circuit. Deoxygenated blood flows through the heart in one direction, entering through the superior vena cava into the right atrium and is pumped through the tricuspid valve into the right ventricle before being pumped out through the pulmonary valve to the pulmonary arteries into the lungs. It returns from the lungs through the pulmonary veins to the left atrium where it is pumped through the mitral valve into the left ventricle before leaving through the aortic valve to the aorta.
Heart Diseases
  • Coronary heart disease
    Coronary heart disease refers to the failure of the coronary circulation to supply adequate circulation to cardiac muscle and surrounding tissue
  • Cardiomyopathy
    Cardiomyopathy literally means "Heart muscle disease" (Myo= muscle, pathy= disease); it is the deterioration of the function of the myocardium (i.e., the heart muscle) for any reason
  • Cardiovascular disease
    Cardiovascular disease is any of a number of specific diseases that affect the heart itself and/or the blood vessel system, especially the veins and arteries leading to and from the heart
  • Ischaemic heart disease
    Ischaemic heart disease – another disease of the heart itself, characterized by reduced blood supply to the organs
  • Heart failure
    Heart failure, also called congestive heart failure (or CHF), and congestive cardiac failure (CCF), is a condition that can result from any structural or functional cardiac disorder that impairs the ability of the heart to fill with or pump a sufficient amount of blood throughout the body
  • Hypertensive heart disease
    Hypertensive heart disease is heart disease caused by high blood pressure, especially localised high blood pressure
  • Inflammatory heart disease
    Inflammatory heart disease involves inflammation of the heart muscle and/or the tissue surrounding it
  • Valvular heart disease
    Valvular heart disease is disease process that affects one or more valves of the heart