What is Normal Respiratory Rate?
April 29, 2026
What is normal respiratory rate? Normal Respiratory Rate = 15 breaths per minute (range = 12 to 18). A respiration rate under 12 or over 25 breaths per minute while resting may be a sign of an un...
The heart is the engine of the human body. As a specialized muscular pump, its primary role is to circulate blood, delivering oxygen and nutrients to every cell while removing metabolic waste.
Understanding how the heart works is the first step in preventing cardiovascular disease. Here are 7 essential facts about the human heart, its anatomy, and its function.
The heart is a hollow, muscular organ located in the chest cavity, slightly to the left of the breastbone (sternum). Its rhythm is the foundation of life.
Primary Function: It pumps oxygenated blood to the body and deoxygenated blood to the lungs.
Clinical Note: The heart is susceptible to various conditions, including Ischaemic Heart Disease (IHD), such as angina and heart attacks, and Chronic Heart Failure (CHF).
Despite its power, the heart is relatively small. In an average adult, it is roughly the size of a closed fist and weighs between 250 and 300 grams.
Fun Fact: While a human heart is light, the heart of a blue whale can weigh up to 200 kg!
The heart is divided into four distinct chambers that work in perfect synchronization to ensure one-way blood flow.
The Atria: The two upper chambers (Right and Left Atrium) receive blood returning to the heart.
The Ventricles: The two lower chambers (Right and Left Ventricle) are thicker and more muscular, responsible for pumping blood out to the lungs and body.
The Valves: Four internal valves act as “gates” to prevent backflow. These are vulnerable to infections like endocarditis.
A normal resting heart rate for an adult is typically between 60 and 100 beats per minute. This means your heart beats approximately 100,000 times a day, circulating about 5 liters (8 pints) of blood.
Bradycardia: A resting heart rate below 60 BPM.
Tachycardia: A resting heart rate above 100 BPM.
Athletic Variation: For elite athletes, a resting rate of 40 BPM is often normal due to high cardiac efficiency.
The heart sits inside a double-layered sac called the pericardium.
Protection: This sac contains a small amount of lubricating fluid that reduces friction as the heart beats and protects it from infection.
Pericarditis: Inflammation of this sac is called pericarditis, often caused by viral infections or, in some regions, tuberculosis.
Even though the heart is full of blood, it cannot absorb oxygen from the blood inside its chambers. It requires its own dedicated supply.
The Supply Line: The coronary arteries branch off the aorta and wrap around the exterior of the heart to provide the muscle with oxygen-rich blood.
Blockages: When these arteries become narrowed or blocked, it leads to coronary artery disease, the leading cause of heart attacks.
The heart generates its own electricity to coordinate contractions.
The SA Node (Sinoatrial Node): Known as the heart’s natural “pacemaker,” these cells initiate the electrical impulse.
The AV Node (Atrioventricular Node): This acts as a gateway, slowing the signal slightly to allow the ventricles to fill with blood before they contract.
Arrhythmias: Disruptions in this electrical timing can cause irregular heartbeats, such as Atrial Fibrillation (AF).
| Feature | Normal Range / Detail |
| Resting Heart Rate | 60–100 BPM |
| Total Daily Beats | ~100,000 |
| Chamber Count | 4 (2 Atria, 2 Ventricles) |
| Primary Vessel | Aorta |
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