The heart is a muscular structure that is situated in the front of the chest. It pumps blood all through the body in a process called circulation. Apart from the heart, the blood vessels and blood as a unit constitute the cardiovascular system.
Table of Contents
- Functions of the Human Heart
- Types of Circulation
- Structure of the HumanHeart
- Structure of the Heart Wall
- Chambers of the Heart
- Blood Vessels
- Facts about Human Heart
- Important Questions about the Human Heart
- Practise Labelling the Human Heart Diagram
Introduction to the Human Heart
The human heart is one of the most important organs responsible for sustaining life. It is a muscular organ with four chambers. The size of the heart is the size of about a clenched fist.
The human heart functions throughout a person’s lifespan and is one of the most robust and hardest working muscles in the human body.
Besides humans, most other animals also possess a heart that pumps blood throughout their bodies. Even invertebrates such as grasshoppers possess a heart like pumping organ, though they do not function the same way a human heart does.
Also Refer:Human Circulatory System
Position of Heart in Human Body
The human heart is located between the lungs in the thoracic cavity, slightly towards the left of the sternum (breastbone). It is derived from the embryonic mesodermal germ layer.
The Function of Heart
The function of the heart in any organism is to maintain a constant flow of blood throughout the body. This replenishes oxygen and circulates nutrients among the cells and tissues.
Following are the main functions of the heart:
- One of the primary functions of the human heart is to pump blood throughout the body.
- Blood delivers oxygen, hormones, glucose and other components to various parts of the body, including the human heart.
- The heart also ensures that adequate blood pressure is maintained in the body
There are two types of circulation within the body, namely pulmonary circulation and systemic circulation.
Pulmonary circulation (blue) and Systemic circulation (red)
Types of Circulation
- Pulmonary circulation is a portion of circulation responsible for carrying deoxygenated blood away from the heart, to the lungs and then bringing oxygenated blood back to the heart.
- Systemic circulation is another portion of circulation where the oxygenated blood is pumped from the heart to every organ and tissue in the body, and deoxygenated blood comes back again to the heart.
Now, the heart itself is a muscle and therefore, it needs a constant supply of oxygenated blood. This is where another type of circulation comes into play, the coronary circulation.
- Coronary circulation is an essential portion of the circulation, where oxygenated blood is supplied to the heart. This is important as the heart is responsible for supplying blood throughout the body.
- Moreover, organs like the brain need a steady flow of fresh, oxygenated blood to ensure functionality.
In a nutshell, the circulatory system plays a vital role in supplying oxygen, and nutrients and removing carbon dioxide and other wastes from the body. Let us gain a deeper insight into the various anatomicalstructures of the heart:
Structure of the HumanHeart
The human heart is about the size of a human fist and is divided into four chambers, namely two ventricles and two atria. The ventricles are the chambers that pump blood and the atrium are the chambers that receive blood. Among these both the right atrium and ventricle make up the “right heart,” and the left atrium and ventricle make up the “left heart.” The structure of the heart also houses the biggest artery in the body – theaorta.
The right and the left region of the heart are separated by a wall of muscle called the septum. The right ventricle pumps the blood to the lungs for re-oxygenation through the pulmonary arteries. The right semilunar valves close and prevent the blood from flowing back into the heart. Then, the oxygenated blood is received by the left atrium from the lungs via the pulmonary veins. Read on to explore more about the structure of the heart.
External Structure of Heart
One of the very first structures which can be observed when the external structure of the heart is viewed is the pericardium.
The human heart is situated to the left of the chest and is enclosed within a fluid-filled cavity described as the pericardial cavity. The walls and lining of the pericardial cavity are made up of a membrane known as the pericardium.
The pericardium is a fibre membrane found as an external covering around the heart. It protects the heart by producing a serous fluid, which serves to lubricate the heart and prevent friction between the surrounding organs. Apart from the lubrication, the pericardium also helps by holding the heart in its position and by maintaining a hollow space for the heart to expand itself when it is full. The pericardium has two exclusive layers—
- Visceral Layer:Itdirectly covers the outside of the heart.
- Parietal Layer: Itforms a sac around the outer region of the heart that contains the fluid in the pericardial cavity.
Structure of the Heart Wall
The heart wall is made up of 3 layers, namely:
- Epicardium – Epicardium is the outermost layer of the heart. It is composed of a thin-layered membrane that serves to lubricate and protect the outer section.
- Myocardium – This is a layer of muscle tissue and it constitutes the middle layer wall of the heart. It contributes to the thickness and is responsible for the pumping action.
- Endocardium – It is the innermost layer that lines the inner heart chambers and covers the heart valves. Furthermore, it prevents the blood from sticking to the inner walls, thereby preventing potentially fatal blood clots.
Internal Structure of Heart
The internal structure of the heart is rather intricate with several chambers and valves that control the flow of blood.
Chambers of the Heart
Vertebrate hearts can be classified based on the number of chambers present. For instance, most fish have two chambers, and reptiles and amphibians have three chambers. Avian and mammalian hearts consists of four chambers. Humans are mammals; hence, we have four chambers, namely:
- Left atrium
- Right atrium
- Left ventricle
- Right ventricle
Atria are thin and have less muscular walls and are smaller than ventricles. These are the blood-receiving chambers that are fed by the large veins.
Ventricles are larger and more muscular chambers responsible for pumping and pushing blood out into circulation. These are connected to larger arteries that deliver blood for circulation.
The right ventricle and right atrium are comparatively smaller than the left chambers. The walls consist of fewer muscles compared to the left portion, and the size difference is based on their functions. The blood originating from the right side flows through the pulmonary circulation, while blood arising from the left chambers is pumped throughout the body.
In organisms with closed circulatory systems, the blood flows within vessels of varying sizes. All vertebrates, including humans, possess this type of circulation. The external structure of the heart has many blood vessels that form a network, with other major vessels emerging from within the structure. The blood vessels typically comprise the following:
- Veins supply deoxygenated blood to the heart via inferior and superior vena cava, and it eventually drains into the right atrium.
- Capillaries are tiny, tube-like vessels which form a network between the arteries to veins.
- Arteries are muscular-walled tubes mainly involved in supplying oxygenated blood away from the heart to all other parts of the body. Aorta is the largest of the arteries and it branches off into various smaller arteries throughout the body.
Also Refer: Difference between Arteries and Veins
Valves are flaps of fibrous tissues located in the cardiac chambers between the veins. They ensure that the blood flows in a single direction (unidirectional). Flaps also prevent the blood from flowing backwards. Based on their function, valves are of two types:
- Atrioventricular valves are between ventricles and atria. The valve between the right ventricle and right atrium is the tricuspid valve, and the one which is found between the left ventricle and left atrium is known as the mitral valve.
- Semilunar valves are located between the left ventricle and the aorta. It is also found between the pulmonary artery and the right ventricle.
Also Read: Blood and its Composition
Facts about Human Heart
- The heart pumps around 6,000-7,500 litres of blood in a day throughout the body.
- The heart is situated at the centre of the chest and points slightly towards the left.
- On average, the heart beats about 100,000 times a day, i.e., around 3 billion beats in a lifetime.
- The average male heart weighs around 280 to 340 grams (10 to 12 ounces). In females, it weighs around 230 to 280 grams (8 to 10 ounces).
- An adult’s heart beats about 60 to 100 times per minute, and a newborn baby’s heart beats at a faster pace than an adult which is about 90 to 190 beats per minute.
Also Refer:Heart Health
To know more about the human heart structure and function, or any other related concepts such as arteries and veins, the internal structure of the heart, and the external structure of the heart,explore BYJU’S Biology. Also, learn aneasy diagram of the heart, concepts and relevant questions for the human heart for Class 10by downloading BYJU’S – The Learning App.
More to Explore:
- Heart Diseases
- Hepatic Portal System
Frequently Asked Questions
1. What is pulmonary circulation? Explain.
Pulmonary circulation is a type of blood circulation responsible for carrying deoxygenated blood away from the heart, and to the lungs, where it is oxygenated. The system then brings oxygenated blood back to the heart to be pumped throughout the body.
2. Define systemic circulation.
In systemic circulation, the heart pumps the oxygenated blood through the arteries to every organ and tissue in the body, and then back again to the heart through a system of veins.
3. Elaborate on coronary circulation and its significance.
The heart is a muscle, and it needs a constant supply of oxygenated blood to survive and work effectively. This is where coronary circulation fulfils this function through a network of arteries and veins in the heart. The coronary arteriessupply oxygenated blood to the heart, and thecardiac veins drain the blood once it has been deoxygenated by the tissues of the heart.
4. Briefly explain the structure of the human heart.
The human heart is divided into four chambers, namely two ventricles and two atria. The ventricles are the chambers that pump blood and atrium are the chambers that receive the blood. Among which, the right atrium and ventricle make up the “right portion of the heart”, and the left atrium and ventricle make up the “left portion of the heart.”
5. Name the chambers of the heart.
- Left atrium
- Right atrium
- Left ventricle
- Right ventricle
6. What is pericardium? Explain its function.
The pericardium is a fibrous membrane that envelops the heart. It also serves a protective function by producing a serous fluid, which lubricates the heart and prevents friction between the surrounding organs. Furthermore, the pericardium also holds the heart in its position and provides a hollow space for the heart to expand and contract.
7. Explain the three layers of the heart wall.
The heart wall is made up of 3 layers, namely:
- Epicardium – This is the outermost layer of the heart. It is composed of a thin layer of membrane that protects and lubricates the outer section.
- Myocardium – This is a layer of muscle tissue that constitutes the middle layer wall of the heart. It is responsible for the heart’s “pumping” action.
- Endocardium – The innermost layer that lines the inner heart chambers and covers the heart valves. Prevents blood from sticking, thereby avoiding the formation of fatal blood clots.
8. Explain the three major blood vessels of the human body.
The blood vessels comprise:
- Veins– It supplies deoxygenated blood to the heart via inferior and superior vena cava, eventually draining into the right atrium.
- Capillaries– They are minuscule, tube-like vessels which form a network between the arteries and veins.
- Arteries – These aremuscular-walled tubes responsible for supplying oxygenated blood away from the heart to all other parts of the body.
9. What is the function of the heart valves? Provide examples of various valves.
Valves are flaps of tissues that are present in cardiac chambers between the veins. They prevent the backflow of blood. Examples include the atrioventricular valves, tricuspid valves, mitral valves and the semilunar valves.
10. What is meant by myocardial infarction?
Myocardial infarction is a serious medical condition where the blood flow to the heart is reduced or entirely stopped. This causes oxygen deprivation in the heart muscles, and prolonged deprivation can cause tissues to die.
Label the Heart Diagram below:
Practice your understanding of the heart structure. Drag and drop the correct labels to the boxes with the matching, highlighted structures.
Instructions to use:
- Hover the mouse over one of the empty boxes.
- One part in the image gets highlighted.
- Identify the highlighted part and drag and drop the correct label into the same box.
- After finishing all the labelling, check your answers.
The heart is a fist-sized organ that pumps blood throughout your body. It's the primary organ of your circulatory system. Your heart contains four main sections (chambers) made of muscle and powered by electrical impulses. Your brain and nervous system direct your heart's function.What are the functions of heart Short answer? ›
It's the muscle at the centre of your circulation system, pumping blood around your body as your heart beats. This blood sends oxygen and nutrients to all parts of your body, and carries away unwanted carbon dioxide and waste products.What is the basic anatomy of heart? ›
The heart is made up of: 4 chambers (2 atria and 2 ventricles) that get blue (deoxygenated) blood from the body. They pump out red (oxygen-rich) blood back to it: The atria get blood coming back to the heart.How many main functions does the heart have? ›
The two main functions of the heart are to pump deoxygenated blood to the lungs in order to receive oxygen, and then to pump oxygenated blood out to all body parts. The circulatory system works to pump blood all throughout the body, carrying with it important molecules such as oxygen and nutrients.What are the 5 main parts of the heart? ›
The heart is made up of four chambers. The upper two chambers are called atria (singular: atrium) and the lower two are known as ventricles (singular: ventricle). Muscular walls, called septa or septum, divide the heart into two sides.What is the most important function of the heart? ›
Your heart is a vital organ. It is a muscle that pumps blood to all parts of your body. The blood pumped by your heart provides your body with the oxygen and nutrients it needs to function.What is 10 heart function? ›
A normal heart pumps blood out of its left ventricle at about 50 to 70 percent — a measurement called an ejection fraction, according to the American Heart Association. “Don was at 10 percent, which is basically a nonfunctional heart,” Dow said. “When a heart is pumping at only 10 percent, a person can die very easily.What are the 4 main arteries of the heart? ›
The right coronary artery, the left main coronary, the left anterior descending, and the left circumflex artery, are the four major coronary arteries.How does the heart function step by step? ›
The right ventricle pumps the low-oxygen blood to the lungs to pick up a fresh supply of oxygen. The left atrium receives to high-oxygen blood from the lungs and pumps it to the left ventricle. The left ventricle pumps the high-oxygen blood to the rest of the body.What muscle is the heart made of? ›
The muscle layer of the heart is termed the myocardium and is made up of cardiomyocytes. The myocardium is found in the walls of all four chambers of the heart, though it is thicker in the ventricles and thinner in the atria.
The heart is a hollow muscular organ about the size of a closed fist. It's in the centre of your chest, behind the breastbone. Each heartbeat sends blood that's rich in oxygen and nutrients to all parts of your body.How big is the heart? ›
The heart weighs between 7 and 15 ounces (200 to 425 grams) and is a little larger than the size of your fist. By the end of a long life, a person's heart may have beat (expanded and contracted) more than 3.5 billion times.What are the 3 main structures of the heart? ›
The outer layer of the heart wall is the epicardium, the middle layer is the myocardium, and the inner layer is the endocardium.Where exactly is your heart? ›
The heart is a complex organ that pumps blood throughout the body. It sits in the chest, slightly left of center, behind the breastbone, and between the lungs.Where is heart located? ›
Overview. The heart and lungs are located in the thorax, or chest cavity. The heart pumps blood from the body to the lungs, where the blood is oxygenated.What carries blood to the heart? ›
A network of arteries and veins also carry blood throughout the body: Arteries transport blood from the heart to the body tissues. Veins carry blood back to the heart.What is the scientific name of heart? ›
The heart is one of the most vital organs of our body. It's the organ in the middle of our circulation system, pumping blood around the body as it beats. The blood sends oxygen and nutrients to the body and carries away unwanted carbon dioxide and waste materials.What are the 4 types of heart failure? ›
- Left-sided heart failure. Left-sided heart failure is the most common type of heart failure. ...
- Right-sided heart failure. The right heart ventricle is responsible for pumping blood to your lungs to collect oxygen. ...
- Diastolic heart failure. ...
- Systolic heart failure.
A score of 120/80 is optimal, and 140/90 is normal for most people. Higher readings mean that arteries aren't responding right to the force of blood pushing against artery walls (blood pressure), directly raising the risk of heart attack or stroke.
High blood pressure and other conditions that make your heart work harder are the main causes of heart failure with preserved ejection fraction. Conditions that stiffen the chambers of the heart such as obesity and diabetes are also causes of this type of heart failure.What is heart blockage called? ›
This condition is called atherosclerosis. The buildup is called plaque. Plaque can cause the arteries to narrow, blocking blood flow. The plaque can also burst, leading to a blood clot.Which artery is the most important? ›
The most important artery is called the left anterior descending artery (LAD). It feeds blood to the whole front wall of the heart, which represents much more muscle than the area fed by either of the other two coronary arteries.How does heart happen? ›
A heart attack occurs when an artery that sends blood and oxygen to the heart is blocked. Fatty, cholesterol-containing deposits build up over time, forming plaques in the heart's arteries. If a plaque ruptures, a blood clot can form. The clot can block arteries, causing a heart attack.Is the heart a muscle or a bone? ›
Your heart is actually a muscular organ. An organ is a group of tissues that work together to perform a specific function. In the case of your heart, this function is pumping blood throughout your body. Additionally, the heart is largely made up of a type of muscle tissue called cardiac muscle.How many layers does the heart have? ›
The walls of the heart are composed of three layers: Epicardium - the outer layer. Myocardium - the middle, muscular layer. Endocardium - the inner layer.What are the cells of the heart? ›
The human heart is composed of four major cell types—cardiac fibroblasts (CFs), cardiomyocytes, smooth muscle cells (SMCs), and endothelial cells (ECs)1.Why is the heart on the left side? ›
The heart's left ventricle has to be bigger as it pumps oxygen rich blood round the whole body, meaning the heart is skewed to the left. The heart is located fairly centrally beneath the breastbone, but it does protrude towards the left.What is the strongest muscle in the heart? ›
Cardiac muscle makes up the wall of the heart and is responsible for the forceful contraction of the heart.Is the heart hollow or solid? ›
Your heart is in the center of your chest, near your lungs. It has four hollow chambers surrounded by muscle and other heart tissue.
The biggest solid internal organ is your liver, followed by your brain, lungs, heart, and kidneys.How heavy is a heart? ›
The human heart weighs less than 1 pound, however, a man's heart is 2 ounces heavier than a woman's heart, on average.What shape is a heart? ›
According to the Heart Institute, "The heart is shaped like an upside-down pear." As for its size... A normal, healthy heart is the size of an average clenched adult fist.What are the 4 main functions of the heart? ›
- Function: Its significant role is to pump blood throughout the body. Enables transport of oxygen-rich blood to all components of the body. Helps regulate adequate blood pressure throughout the body. Transfers nutrients to cells, tissues, and all parts of the body.
- Final answer:
- Pumping oxygenated blood to other body parts.
- Pumping hormones and other vital substances to different parts of the body.
- Receiving deoxygenated blood and carrying metabolic waste products from the body and pumping it to the lungs for oxygenation.
- Maintaining blood pressure.
The function of the heart is to contract and pump oxygenated blood to the body and deoxygenated blood to the lungs.What is the heart made of? ›
The heart wall consists of three layers: the endocardium, myocardium and epicardium. The endocardium is the thin membrane that lines the interior of the heart. The myocardium is the middle layer of the heart. It is the heart muscle and is the thickest layer of the heart.What are the 10 function of heart? ›
It supplies oxygen and nutrients to the tissues and removes carbon dioxide and waste from the blood. It also helps to maintain adequate blood pressure throughout the body. Heart pumps the blood throughout the body, hence playing an important role in maintaining body temperature.Is the heart a Muscle or an organ? ›
The heart is a hollow muscular organ about the size of a closed fist. It's in the centre of your chest, behind the breastbone. Each heartbeat sends blood that's rich in oxygen and nutrients to all parts of your body.