In this section, you will learn and understand, how much does human heart weigh, the working of the human heart, and some diseases related to the human heart.
If we talk about the weight of the human heart, we shall come to know that the weight of man and woman are not equal. A man’s heart weighs approximately 10 ounces, while a woman’s heart weighs about 8 ounces.
Like the hearts of birds and other mammals, the human heart is a muscular organ, consisting of four chambers i.e. two atria (Singular atrium) and two ventricles. Atria are the upper chambers (left and right) receiving blood from body parts, while ventricles are lower chambers (left and right) pumping blood to the body. The bulk of the walls of heart chambers is made of Cardiac muscles (The term cardiac is related to the heart). The human heart is situated between the lungs, in the thorax under the breastbone. The heart’s outer wall consists of three layers. The outermost wall layer or epicardium is the inner wall of the pericardium, the middle layer contains the muscles that contract. In the inner layer which is called the endocardium, between the heart walls and pericardium, there is a fluid, called pericardium fluid which reduces friction between heart walls during contraction, otherwise, they may rupture. In humans, the heart is roughly the size of a large fist and weighs about between 280g to 340g in men and 230g to 280g, in women according to Henry Gray’s “Anatomy of the Human body”.
WORKING
The human heart works like a double pump. It receives oxygenated blood (blood with more oxygen) from the lungs and transfers it to the body tissues, at the same time receiving de-oxygenated blood (blood with less oxygen) from the body and transferring it to the lungs to get oxygen. The human heart is generally felt to be on the left side because of the stronger chamber of the heart i.e. left ventricle.
The right atrium receives deoxygenated blood from body parts through the major veins, the superior and inferior vena cava. After contraction of the right atrium, blood passes to the right ventricle. The opening between the right atrium and right ventricle is guarded by the tricuspid valve because it has three flaps. When the right ventricle contracts, the blood passes to the pulmonary trunk, which leads blood to the lungs. The tricuspid valve prevents the backflow of blood from the right ventricle to the right atrium. The pulmonary semilunar valve which is present at the base of the pulmonary trunk prevents the backflow of blood from the pulmonary trunk to the right ventricle
The oxygenated blood from the lungs is brought up by the pulmonary vein to the left atrium. The left atrium contracts and pumps blood to the left ventricle. The walls of the left ventricle are the thickest ones, about half an inch in thickness. When the left ventricle contracts, the oxygenated blood passes to the aorta, which transfers blood to all parts of the body except the lungs. The opening between the left atrium and left ventricle is guarded by a bicuspid valve, as it contains two flaps. The bicuspid valve prevents the backflow of blood from the left ventricle to the left atrium. Similarly, an aortic semilunar valve which is present at the base of the aorta prevents the backflow of blood from the aorta to the left ventricle. In the heart, both atria are filled and contract together to pump blood to both ventricles, similarly both ventricles after filling pump blood out of the heart. A wall of muscle called the septum separates the two sides of the heart. The heart contains the electrical “pacemaker” cells, which cause it to contract, producing a heartbeat. There are two circulations, “pulmonary and systemic” taking place simultaneously. A brief description of both circulations is demonstrated below:
- Pulmonary circulation
The pathway on which deoxygenated blood is carried from the heart to the lungs and in return oxygenated blood is carried from the lungs to the heart is termed pulmonary circulation.
- Systemic circulation
The pathway on which oxygenated blood is carried from the heart to body tissues and in return deoxygenated blood is carried from body tissues to the heart is known as systemic circulation.
The average human heart beats 70 times per minute. It would beat about 2.2 billion times during a lifetime of 60 years.
HEART DISEASES
- Atherosclerotic disease:
Cardiovascular disease symptoms may differ between men and women. Men have more likely to have chest pain, while women are more likely to have different symptoms along with chest problems such as nausea and extreme fatigue as well as shortness of breath. Symptoms of atherosclerosis are given below:
Symptoms
- Pain in the neck jaw, throat, upper abdomen, or back,
- Shortness of breath,
- Chest pain, chest pressure, and chest discomfort,
- Weakness or coldness in legs or arms if the blood vessels in those parts become narrow.
Treatment
- A number of clinical trials with satins, which have an anti-inflammatory action have demonstrated that reducing inflammation has a major therapeutic benefit.
- Several significant anti-inflammatory targets have been identified and associated therapeutics have been developed for the treatment of atherosclerosis, these include phospholipase A2 inhibitors and anti-leukotrienes, and anti-cytosine therapeutics.
- Heart arrhythmias
It is an abnormal heartbeat. In this problem, the heart beats too quickly, too slowly, or beats irregularly.
Symptoms of heart arrhythmias are;
- Dizziness
- Fainting(syncope)
- Chest or discomfort
- Shortness of breath
- Slow heartbeat
- Quick heartbeat
- Fluttering in the chest cavity
Treatment
Treatment of heart arrhythmias may involve the use of an implantable device.
- Pacemaker
A pacemaker is an implantable device that assists to control abnormal heart rhythms. In case of an abnormal heart rate, the pacemaker emits electrical impulses that stimulate the heart to beat at a normal rate.
- Implantable Cardioverter defibrillator (ICD)
It is a device that detects abnormal heart rhythm, it sends low or high-energy shocks to reset the heart to a normal rhythm. An ICD does not prevent an abnormal heart rhythm from occurring, it just treats it, if it happens.
- Surgery
In some conditions, surgery may be recommended treatment for heart arrhythmias,
- Maze procedure
In this procedure, a surgeon makes a series of surgical incisions in the heart tissues in the upper half of the heart i.e. atria to create a sequence or maze of scar tissue. The reason is that the scar tissues don’t conduct electricity, it only interferes with stray electrical impulses that cause some type of arrhythmia. The procedure is effective but because it requires surgery, it is generally reserved for those who do not to other treatments.
- Coronary Bypass Surgery
If there is severe coronary artery disease in addition to arrhythmias the patient requires coronary bypass surgery. This procedure may improve the flowing of blood to the heart.