The Human Heart

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Function

What does the heart do?

The right side of the heart - Pumps blood to the lungs, where oxygen is added to the blood and carbon dioxide is removed.

The left side of the heart - Pumps blood to the rest of the body, where oxygen and nutrients are delivered to tissues and waste products (e.g. carbon dioxide) are transferred to the blood for removal by other organs (e.g. lungs and kidneys).

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Anatomy

Where is the heart?

The heart is located in the front of the chest. It sits slightly behind and to the left of the sternum (breastbone). The ribcage protects the heart. The heart is slightly on the left side of the body. It sits between the right and left lungs.

🤓 Fun Fact 🤓
The left lung is slightly smaller to make room for the heart in the left chest.

What makes up the heart?

1. Walls

The heart walls are the muscles that contract and relax to send blood throughout the body. A layer of muscular tissue called the septum divides the heart walls into the left and right sides. The heart walls have three layers which are the;

• Endocardium - inner layer


• Myocardium - muscular middle layer


• Epicardium - protective outer layer

🤓 Fun Fact 🤓
The epicardium is one layer of the pericardium. The pericardium is a protective sac that covers the entire heart. It produces fluid to lubricate the heart and keep it from rubbing against other organs.

2. Chambers

You have 2 chambers on the top (atrium) and 2 on the bottom (ventricle), one on each side of the heart which are the;

• Right atrium - The right atrium pumps the blood to the right ventricle. 2 large veins deliver deoxygenated blood to the right atrium. The superior vena cava carries blood from the upper body. The inferior vena cava brings blood from the lower body.


• Right ventricle - The lower right chamber pumps the deoxygenated blood to the lungs through the pulmonary artery. The lungs reload blood with oxygen.


• Left atrium - After the lungs fill blood with oxygen, the pulmonary veins carry the blood to the left atrium. This upper chamber pumps the blood to the left ventricle.


• Left ventricle - The left ventricle is slightly larger than the right. It pumps oxygenated blood to the rest of the body.

🤓 Fun Fact 🤓
The plural of atrium is atria.

3. Valves

The heart valves are like doors between the heart chambers. They open and close to allow blood to flow through.

The atrioventricular (AV) valves open between the upper and lower heart chambers. They include;

• Tricuspid valve - Door between the right atrium and right ventricle.


• Bicuspid valve - Door between the left atrium and left ventricle.

Semilunar (SL) valves open when blood flows out of the ventricles. They include;

• Aortic valve - Opens when blood flows out of the left ventricle to the aorta (artery that carries oxygenated blood to the body).


• Pulmonary valve - Opens when blood flows from the right ventricle to the pulmonary arteries (the only arteries that carry deoxygenated blood to the lungs).

🤓 Fun Fact 🤓
Mitral valve is the other name for Bicuspid valve.

4. Blood vessels

The heart pumps blood through three types of blood vessels:

• Arteries - Carry oxygenated blood from the heart to the body’s tissues. The exception is the pulmonary arteries, which go to the lungs.


• Veins - Carry deoxygenated blood back to the heart.


• Capillaries - Small blood vessels where the body exchanges oxygenated and deoxygenated blood.

🤓 Fun Fact 🤓
The heart receives nutrients through a network of coronary arteries. These arteries run along the heart’s surface. They serve the heart itself.

5. Electrical conduction system

The heart’s conduction system is like the electrical wiring of a house. It controls the rhythm and pace of the heartbeat which includes;

• Sinoatrial (SA) node - Sends the signals that make the heart beat.


• Atrioventricular (AV) node - Carries electrical signals from the heart’s upper chambers to its lower ones.

The heart also has a network of electrical bundles and fibers which are;

• Left bundle branch - Sends electric impulses to the left ventricle.


• Right bundle branch - Sends electric impulses to the right ventricle.


• Bundle of His - Sends impulses from the AV node to the Purkinje fibers.


• Purkinje fibers - Make the heart ventricles contract and pump out blood.

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Care

How to keep the heart healthy?

• Exercise frequently.


• Limit the sodium intake.


• Maintain a healthy Body Mass Index (BMI) for the sex and age.


• Include plenty of fruits, vegetables and whole grains in the diet.


• Manage the daily stress with healthy habits such as meditation or allocating selfcare time.

Coded by Lohveena Shivas