A major venous vessel that carries oxygen-depleted blood from the upper part of the body to the heart. Interesting fact: The superior vena cava is one of the largest veins in the human body.

The largest vein in the body, which carries blood from the lower limbs and torso to the heart. Interesting fact: The inferior vena cava passes through the diaphragm and enters the right atrium of the heart.

The main and largest artery in the body, carrying oxygen-rich blood from the left ventricle to the rest of the body. Interesting fact: The aorta has wall thicknesses of about 2 mm and a diameter of up to 3 cm in an adult.

The heart is a hollow, muscular, cone-shaped organ, weighing about 300 grams, located in the thoracic cavity behind the sternum and slightly to the left. It consists of four chambers: two atria and two ventricles, functioning as a pump to circulate blood throughout the body. The heart rhythmically contracts and relaxes, providing circulation for the transport of oxygen and nutrients, as well as the removal of metabolic wastes. The heart is surrounded by the pericardium (heart sac), which consists of two layers and contains a small amount of fluid to reduce friction during contractions. This structure reduces wear and protects the heart from external influences, ensuring its efficient operation. Interesting fact: The human heart beats an average of 70 times per minute, pumping about 5 liters of blood.

A large artery that supplies blood flow to the lower limbs. Interesting fact: The femoral artery is a continuation of the external iliac artery and one of the main arteries where the pulse is checked in cases of trauma or shock.

A vein that returns blood from the lower limbs to the heart. Interesting fact: The femoral vein is used in medicine for venous access in emergency situations, as it is one of the most accessible large veins.

A liquid connective tissue consisting of plasma and formed elements (erythrocytes, leukocytes, platelets), performing transport, thermoregulatory, and regulatory functions. Plasma: A clear fluid containing mineral salts, proteins, glucose, vitamins, known as serum without fibrinogen. Erythrocytes: Nucleus-free, contain hemoglobin for gas transport. Leukocytes: Colorless cells, formed in the bone marrow and lymphatic system, provide immunity. Platelets: Involved in blood clotting, originate from the bone marrow.