Top 12 Heart Functions with Parts, Location, & Diagram

Why is babies’ heart rate twice as fast as adults?

Pumping 2,000 gallons blood with 100,000 beats a day, the heart tirelessly works till your last breath.

1 in 3 US women dies of heart disease!

Larger hearts beat slower. How? Read on to discover fascinating facts about the function of heart.

If you know “What is the function of the heart?” it’ll help you ease its workload and prevent a disorder.

Here’re the primary and secondary heart functions in brief.

In addition to elaborating on the heart function, the present article also provides an easy account of human heart structure, parts, diagram, location, and facts.

Also, you’ll get answers to the following FAQs about the heart:

It is the main organ of your body's circulatory system, pumping blood throughout the body.

To understand the heart structure and function, you can call it a muscular pump that contracts at regular intervals in order to squeeze the blood through it into the blood vessels.

Heart Location:

Does the heart lie entirely to the left of the midline?

The location of the heart is in the same compartment which houses and safeguards the lungs – the thorax.

Also called the chest, the thorax sits between the neck and the diaphragm and is partially encased by the ribcage.

Resting on the superior surface of the diaphragm, the heart is located posterior to the costal cartilages and the sternum.

The space occupied by the heart between the pleural cavities is called the middle mediastinum.

And the middle mediastinum can be defined as the space inside the pericardium, which forms a covering around the heart.

According to Arthur Selzer, the heart is in the center of the chest, located slightly more to the left than to the right.

Two-thirds of the organ lies to the left of the midline while the remaining one-third goes to the right of the middle.

Its apex is directed downward and leftward.

So, the organ assumes an oblique position inside the thorax.

Top 12 Heart Functions in Detail:

1. Pulmonary Circulation:

The pulmonary component of the circulatory system begins at the junction between the right ventricle and the pulmonary artery. purify the blood, i.e. restore its oxygen content and eliminate excess carbon dioxide.

The blood that the superior and inferior vena cavae collect from the upper and lower halves of the body, respectively, is deficient in oxygen.

So, the right ventricle pushes this blood into the pulmonary artery via the pulmonic valve.

Here it is to be noted that the pulmonary arteries are one of the two arteries that carry deoxygenated blood, the other being the umbilical arteries.

A pulmonary artery shunts the blood away from the heart to the lung to re-saturate it with oxygen.

Numerous pulmonary capillaries diverged from the right and left pulmonary arteries help the blood take up oxygen and unload carbon dioxide in the lungs.

The blood fully saturated with oxygen is transported back to the heart via the pulmonary vein.

The veins carrying oxygenated blood empties its contents into the left atrium.

The upper left chamber then pushes it into the left ventricle via the left atrioventricular (or mitral) valve.

The oxygen-rich blood leaves the heart and enters the aorta through the aortic valve, which marks the starting point of the systemic circulation.

2. Systemic Circulation:

It starts at the aortic valve where the aorta – the largest artery in your body – joins the left atrium and ends at the junction of the superior and inferior vena cavae with the right atrium.

Its job is to supply the peripheral organs and tissue beds with oxygen-rich blood and return the venous or oxygen-depleted blood back to the pumping organ.

While large and small arteries distribute the blood throughout the body, a network of veins recollects and brings it back for oxygenation.

Serving as a connecting link between the arteries and veins, the capillaries are the exchange vessels.

The main job of the capillaries is to facilitate the exchange of nutrients and fluid between the blood and the interstitial space.

Did you know?

The systemic circulation contains nearly 80 percent of your body’s total blood volume!

The pulmonary and coronary vascular circuits contain 9-12 and 8-11 percent of the total blood volume, respectively.

3. Coronary Circulation:

It begins at coronary ostia where the ascending aorta starts branching off and ends at the junction between the coronary sinus and the right atrium.

Coronary arterial circulation and coronary venous circulation are the two subdivisions of this system.

The former supplies the cardiac muscle tissue with oxygen and nutrients while the latter is concerned with the removal of carbon dioxide and waste products.

The aorta or the ‘gigantic vasa vasorum of the heart’ (as Hyrtl defined it) branches off to form the left and right coronary arteries.

So, the first destination of the oxygenated blood that leaves the left ventricle is the heart itself.

The right coronary artery divides to form conus branches anteriorly and the sinoatrial branch posteriorly.

Many divisions and sub-divisions of the right and left arteries terminate in the capillary beds of the myocardium.

These capillary beds are joined by the reverse hierarchy of venules and small and large veins.

Most of the large veins converge to form the coronary sinus – the main venous channel. Other veins directly empty into the right atrium.

Like that of other organs, the coronary circulation also has a network of arteries and veins.

But it differs in that it does not go through the vena cava and directly empties into the upper right chamber.

4. Splanchnic Circulation:

Splanchnic circulation refers to the circulatory circuit committed to the blood supply to the splanchnic organs like the spleen, pancreas, liver, and gastrointestinal tract.

It involves all blood flow originating from three major arteries, viz. the celiac, the superior mesenteric, and the inferior mesenteric.

Splanchnic circulation receives about 25 percent of the total cardiac output.

The components of the splanchnic circulation include splenic, pancreatic, hepatic, small intestinal, and gastric circulations.

All these circulations are arranged in parallel with one another.

Did you know?

The splanchnic circulation can act as a blood reservoir and help regulate cardiac output.

A large meal can result in a 30 to 100% increase in blood flow to the splanchnic organs as they are involved in digestion and absorption.

5. Cutaneous Circulation:

It refers to the blood flow to ‘cutis’ or the skin tissue.

Local metabolic factors do not control the cutaneous circulation.

The requirements of the skin for oxygen and nutrients are relatively small.

Maintenance of the body temperature is the primary job of the cutaneous circulatory circuit.

Fluctuations in the internal and ambient body temperatures can affect blood flow to the skin.

6. Cerebral Circulation:

The metabolically active regions of the brain are irrigated by this circulatory network.

Involving the internal carotid and vertebral arteries, this supply network is tasked with the selectively and specifically pushing the blood to the master organ.

Another job of the cerebral circulation is to defend the brain from fluctuations in the concentrations of oxygen, carbon dioxide, and cerebral perfusion pressure.

7. Pumping Interstitial Fluid:

Researchers have recognized and appreciated the role of the heart in pumping the interstitial fluid from the blood into the extracellular space.

Afterwards, the lymphatic system is tasked with returning the excess fluid in the interstitial space back to the heart.

8. Generation of electrical impulse:

You owe your life to the rhythmic contractions of the heart.

70 times/min is the average rate of the contraction of an adult’s heart at rest.

A well-organized contraction of various parts of the organ is essential for the proper functioning of the circulatory system.

Specialized cells distributed through the heart serve as the sites for the origination and conduction of electrical impulses.

Such cells consist of the pacemaker and the conducting system.

While the pacemaker is responsible for the initiation of cardiac action, the conducting system is tasked with the distribution of the electrical impulses throughout the heart.

The specialized cardiac cells can be grouped into 3 types of structures: nodes, bundles with branches, and the terminal part of the branches.

Here the 2 nodes consist of larger accumulations of cells and the bundles are nerve-like conduits.

The upper and lower nodes are called the S-A (sinoatrial) and the A-V nodes, respectively.

While all the specialized cells have the capacity to generate an electrical impulse, it is the S-A node that acts as the primary pacemaker and has the fastest rate of discharge.

Did you know?

The process involved in the regulation of electrical impulses is analogous to the discharge and recharge of a battery.

9. Distribution of Nutrients:

Delivering a required amount of nutrients is one of the principal tasks assigned to the cardiovascular system.

After breakdown in different segments of the gastrointestinal canal, the digested food particles enter the bloodstream from the small intestine.

As a result of heart function, every cell finds what it needs delivered to its doorstep.

All the body tissues need different types of nutrients to extract energy from.

They include carbohydrates, proteins, lipids, enzymes, vitamins, and minerals.

The nutrients are also used as raw materials for growth, reproduction, and maintenance of various systems.

10. Oxygen Supply:

Oxygen is the most essential fuel for all the tissues in your body.

This fuel is delivered to every individual cell via the blood circulatory system.

As a major organ of the circulatory circuit, the heart helps all the tissues ‘breathe’.

While ‘breathing’, cells extract oxygen from the bright-red arterial blood and deposit carbon dioxide in its place.

11. Hormones Delivery:

The hormones produced by a specific type of tissue need to be distributed to all cells of the body.

And the circulating blood renders its services for the execution of this job.

Secreted into the extracellular fluid, hormones readily enter the blood through passive diffusion caused by steep concentration gradients.

12. Disposing of Wastes:

The principal waste product of tissues is carbon dioxide.

Other waste products include salts, excess water, and nitrogenous wastes.

As the principal organ of the circulatory system, your heart plays an important role in the transportation of the unwanted substances to the point of their removal.

Human Heart Diagram:

What is Heart

As you can see in the human heart diagram, there are 4 chambers in this tireless pumping organ.

All the chambers work in a perfectly coordinated manner for the successful execution of different heart functions.

The right chambers contain unclean or the deoxygenated blood.

On the other hand, the left chambers contain clean or oxygenated blood.

Just look at the different parts of the heart to get a better understanding of the heart function.

Heart Structure and Parts

The heart structure consists of connective tissue and cardiac muscles.

The latter is a type of involuntary muscle.

Here’re some interesting facts about the heart parts and functions.

The cardiac muscle contracts and relaxes on its own without requiring you to deliberately apply force.

Your heart is a delicate organ.

Any damage to it will cause an interruption in the heart functions.

So, it gets protection from the rib cage.

Concerning shape, it looks like a cone.

The base of this cone is positioned upward which gradually tapers down to the apex.

The pumping organ is roughly the size of a wrist.

It measures 12 cm, 8 cm, and 6 cm along the length, width, and thickness, respectively.

The effect of the exercise on the muscles of the heart organ is the same as shown by the skeletal muscles.

That is, as an outcome of exercise, they grow both in size and strength.

That is why well-trained athletes usually have much larger hearts.

Such a thing also enhances heart function.

1. Cardiac Chambers

While a frog’s heart is 3-chambered, a human heart has 4 chambers.

The upper 2 chambers are called the left and right atria.

The lower 2 chambers are called the left and right ventricles.

The right atrium and ventricle contain oxygen-depleted blood collected from the upper and lower parts of the body through the superior and inferior vena cavae.

On the other hand, the left atrium and ventricle contain oxygen-rich blood, which is pumped through the whole body through the aorta.

2. Heart Layers

An inner lining, the heart muscle, and the outer covering are the 3 major layers of the heart.

These layers are called endocardium (inner), myocardium (middle), and pericardium (outer).

The outer layer or pericardium can be distinguished into an outer lining or epicardium and a loose sac.


You might know all cells within your heart’s conducting system are capable of electrical impulse formation.

While some are actively involved in the rhythmic contractions, others usually serve as standby pacemakers.

In other words, different accumulations of cells or pacemakers are activated at different times in priority order.

Researchers have identified three types of pacemakers existing in your heart, i.e. primary, secondary, and tertiary.

1. Primary Pacemaker:

Owing to the highest discharge rate, the SA node has been designated as the leading primary pacemaker.

The SA or sinoatrial node is found at the junction of the right atrium and the superior vena cava.

The discharge of the electrical potential from the SA node or the primary pacemaker activates the conduction system.

An electrical impulse traveling through the conducting system induces contraction of the cardiac muscle.

The discharge of electrical potential is termed as depolarization.

After depolarization, the specialized cells in the SA node start rebuilding electrical potential for the next impulse.

The regeneration of electrical potential is called repolarization.

You can note that the process of the depolarization and repolarization in the heart is analogous to the discharge and recharge of a battery!

2. Secondary Pacemaker:

The secondary pacemaker consists of the lower part of the AV node at its junction with the bundle of His.

You can locate the AV node in the lower septal wall of the atrium.

And the bundle of His emerges from the lower part of the AV node and enters the junction between the ventricles and the atria.

In comparison with that of the primary one, its rate of discharge is considerably low – just around 50 times/min.

It is activated only when its primary counterpart stops to discharge.

3. Tertiary Pacemaker:

When the primary and secondary impulse formation systems stop working, the tertiary pacemaker is tasked with assuming their role.

It is the tertiary center in the ventricular conducting system.

The tertiary pacemaker acts as the 3rd line of defense against the failure of the impulse to reach the lower chambers of the heart.

The tertiary pacemaker consists of the lower divisions of the conducting system, including the Purkinje network.

The Purkinje network is formed from the division and subdivision of the principal branches (left and right bundle branches) of the bundle of His.

Being slower than that of both the primary and secondary pacemakers, its rate of discharge is just about 30 to 40 times per minute.

An interruption in the connection between the Purkinje system and the AV node serves as a trigger for the activation of the tertiary impulse formation unit.

In this case, the atria and the ventricles contract at different rates.

It is because, obeying the primary pacemaker, the atria contract at a faster rate. And, under the influence of the tertiary pacemaker, the ventricles contract at a slower pace.

Heart Valves:

To separately manage systemic and pulmonary circulations, your heart needs to maintain the unidirectional flow of the blood.

A few-word answer to “What is the function of the heart valves?” is they maintain a one-way flow of the blood.

So, they act like the check valves like those installed in the water supply system in your home.

The 4 heart valves are bicuspid, tricuspid, pulmonary, and aortic.

Two of them are located between the heart chambers to control the flow of the blood from the atria to the ventricles.

The remaining two valves – pulmonary and aortic – control the flow of the blood out of the ventricles.

1. The Mitral Valve:

Consisting of two leaflets, it is also called a bicuspid valve.

It is located between the left atrium and the left ventricle.

The mitral valve prevents the backflow of blood from the lower left chamber to the upper left chamber.

2. The Tricuspid Valve:

Having 3 leaflets, the tricuspid valve is located between the right atrium and the right ventricle.

It stops the flow of deoxygenated blood back from the lower right chamber to the upper right chamber.

The tricuspid valve regulates the pulmonary blood flow.

3. The Pulmonary Valve:

This check valve is located at the junction between the pulmonary artery and the right ventricle.

In the presence of this valve, the oxygen-depleted blood from the pulmonary artery does not leak into the lower right chamber of the heart.

4. The Aortic Valve:

Located between the largest artery – the aorta – and the left ventricle, the aortic valve regulates the flow of the oxygen-rich blood from the heart to the various tissues and organs of the body.

Coronary Arteries and Veins

The coronary arteries and veins collectively make up the blood circulatory network dedicated to the heart muscle.

Like other arteries, the coronary arteries too contain oxygenated blood.

Similarly, the coronary veins collect deoxygenated blood from the heart tissue and carry it to the right atrium for oxygenation.

Heart’s Functional Anatomy:

Sound knowledge of the heart’s functional anatomy would help you maintain and enjoy cardiac health.

The heart functions involve the supply of oxygenated blood to all parts of the body.

The circulatory system consists of three main types of blood vessels: arteries, veins, and capillaries.

Arteries carry oxygenated blood and distribute it to different parts of the body.

On the other hand, the veins receive unclean blood, containing carbon dioxide and waste products, from the body parts and take it back to the heart.

The heart contains both the oxygenated and deoxygenated blood.

It is its job to keep both separately in order to avoid contamination of the pureblood.

The right chambers of the heart receive blood, devoid of oxygen, from the veins.

This blood then goes to the lungs to receive oxygen and get rid of carbon dioxide.

Afterward, this oxygen-rich blood goes back to the heart from where it reaches all the body parts through the arteries.

In this way, every individual cell can get oxygen.

This oxygen will assist in the process of extracting energy from food.

Read on to get a bit detailed explanation of “How does the heart function?”

A double-walled membrane, the pericardium, separates the right and left chambers.

That way it prevents oxygen-rich blood from mixing up with the one without oxygen.

So, the heart functions go smoothly.

Deoxygenated blood enters the right atrium.

The valve present between the right atrium and the right ventricle is the tricuspid valve.

It opens to let the blood flow into the right ventricle.

The valve then closes to prevent the backward flow of the blood.

This deoxygenated blood enters the pulmonary artery and moves to the lungs to replenish its oxygen content.

This oxygen-rich blood then comes back to the heart through the pulmonary vein.

The left atrium welcomes this oxygenated blood into its cavity.

The mitral valve between the left atrium and the left ventricle opens to let the blood flow into the left ventricle.

It then closes to prevent the backward flow of blood.

Finally, there is pumping of the blood into the aorta from where it is distributed to the rest of the body through the arteries.

So, you can say that the main function of the heart is to supply all the body cells with oxygen and nutrients through the circulatory network.

Function of the Blood and Blood Vessels:

You might already know a bit about the function of the blood.

Primarily, it serves as a circulatory fluid.

The blood carries the respiratory gases and nutrients to every individual cell in the body.

On its return, it brings carbon dioxide – a waste respiratory gas – for its discharge out of the body.

On the other hand, the function of blood vessels is to serve as a passage for the blood to flow through.

The blood vessels are of three types.

It is the capillaries where the exchange of gases and nutrients takes place with the individual cells.

The Human Heart Facts

Here are some of the human heart facts which will add a lot to the existing pool of your knowledge about the tireless pumping organ.

  • Every 3rd US woman dies of a heart condition!
  • The divers slow down their heartbeat to economize the use of oxygen.
  • An adult’s heart beats 80 times/min but it reduces to 60 beats/min when you are asleep!
  • With the lungs being relatively non-functional, the fetus uses the placenta to get oxygen from the mother’s uterus.
  • After the flow of blood from the placenta is cut and the fetus takes its first breath, the heart chambers undergo final septation.
  • Your heart lies between the right and left lungs which occupy the lateral spaces called the pleural cavities.
  • The average rate of your heartbeat is 72 times per minute. In one day, the heart beats over a hundred thousand times!
  • An average heart can pump around two thousand gallons of blood throughout the body every day.
  • The heart can continue to beat for a while even if you separate it from the body if there is a supply of oxygen.
  • The heart muscles can contract in response to the electrical impulses.
  • In response to exercise, the cardiac muscles tend to grow both in size and strength. This is the very reason that the hearts of athletes are much larger.

Diseases of the Heart

Coronary Artery Disease

The blood vessels that transport blood to the heart become narrow due to deposition of plaque.

It forces the heart to work harder.

As a result, the heart muscle gradually becomes weak.

This fatal disease is caused by a high blood cholesterol level.

Myocardial Infarction

It is one of the most dangerous heart diseases.

More commonly known as heart attack, myocardial infarction may lead to death on the spot if the individual is unable to get prompt medical help.

A heart attack more commonly occurs in patients who are already suffering from coronary artery disease.

The flow of blood to the heart is either reduced or there is a complete blockage.

It deprives the heart cells of oxygen.

Consequently, all the heart functions come to an end.

Congestive Heart Failure

It is a common heart disease that develops as a result of coronary artery disease or a heart attack.

The heart of the patient suffers from damage and is unable to perform the heart function up to its full capacity.

As a result, insufficient blood is pumped.

And the body's oxygen requirements are not fulfilled.

The patients experience fatigue and shortness of breath.

Other Topics Of Heart

  • Are the heart and the spleen equal in size?
  • Why do the athletes have much larger hearts?
  • What prevents impure blood from contaminating impure blood?
  • How does the systemic circulation differ from the pulmonary circuit?
  • Which heart condition is the most common cause of death worldwide?
  • How long does it take to die after the heart stops beating?
  • Who believed the heart weighed no more than a feather?
  • Is it true about the heart – the bigger the better?
  • How can you use your brain to slow down your heartbeat?
  • How long does it take the heart to circulate the blood throughout the body?
  • How do the hearts of a fetus and an adult differ?
  • What is a heart block?
  • Why is babies’ heart rate twice as fast as adults?

About the Author

Posted by: M. Isaac / Senior writer

A graduate in biological sciences and a PhD scholar (NCBA&E University, Lahore), M. Isaac combines his vast experience with a keen and critical eye to create practical and inherently engaging content on the human body. His background as a researcher and instructor at a secondary school enables him to best understand the needs of the beginner level learners and the amateur readers and educate them about how their body works, and how they can adopt a healthier lifestyle.

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