Plasma makes up around 55% of the blood and serves as the liquid medium that carries blood cells, nutrients, hormones, and waste products.

Red blood cells contain hemoglobin, which binds to oxygen, allowing these cells to transport oxygen from the lungs to tissues throughout the body.

Platelets are cell fragments that play a crucial role in blood clotting, helping to stop bleeding when injuries occur.

White blood cells, specifically a type called lymphocytes, produce antibodies that help fight off infections by targeting foreign pathogens.

Platelets activate and clump together at the site of a wound, forming a clot that helps stop bleeding.

Arteries carry oxygenated blood away from the heart to the body, except for the pulmonary artery, which carries deoxygenated blood to the lungs.

Veins carry blood back to the heart, typically deoxygenated, except for the pulmonary vein, which carries oxygenated blood from the lungs to the heart.

Capillaries have thin walls, which allow gases like oxygen and carbon dioxide, as well as nutrients, to be exchanged between blood and tissues.

Valves in veins ensure that blood flows in one direction back toward the heart, preventing backflow due to lower pressure in these vessels.

Most arteries carry oxygenated blood, except for the pulmonary artery, which carries deoxygenated blood from the heart to the lungs.

The left atrium receives oxygen-rich blood from the lungs through the pulmonary veins and then pumps it into the left ventricle.

The right ventricle pumps deoxygenated blood to the lungs via the pulmonary artery for oxygenation.

In a double circulatory system, there are two circuits: one for oxygenating blood through the lungs (pulmonary circuit) and another for distributing oxygenated blood to the body (systemic circuit).

The coronary arteries provide oxygen and nutrients to the heart muscle itself, ensuring that it functions properly.

The left side of the heart receives oxygenated blood from the lungs and pumps it to the rest of the body.

Gas exchange takes place in the alveoli, small air sacs in the lungs where oxygen is absorbed into the blood, and carbon dioxide is released.

The alveoli provide a large surface area for the exchange of gases between the lungs and the blood.

A concentration gradient allows oxygen to move from the alveoli (where it is in high concentration) into the blood and carbon dioxide to move from the blood (where it is in higher concentration) into the alveoli.

Oxygen is taken into the blood from the alveoli, while carbon dioxide is expelled from the blood into the alveoli for exhalation.

The diaphragm contracts and flattens during inhalation, increasing the volume of the chest cavity and drawing air into the lungs.

Coronary heart disease occurs when fatty deposits build up inside the coronary arteries, restricting blood flow to the heart muscle.

A stent is inserted into a narrowed artery to hold it open, ensuring that blood can flow through it more easily.

Mechanical valves are durable but require lifelong medication to prevent clotting, whereas biological valves (from animals) may have a shorter lifespan but often don’t require such medication.

An artificial pacemaker sends electrical signals to help maintain a regular heartbeat when the heart’s natural pacemaker (SA node) is not functioning properly.

A bypass surgery involves creating a new pathway for blood to flow around a blocked section of an artery, allowing blood to reach the heart muscle.