Blood vessels are essential components of the cardiovascular system, serving as conduits for blood flow throughout the body. There are five main types of ...

The walls of blood vessels, whether arteries or veins, have three distinct layers or tunics. Tunica externa is the outermost layer infiltrated with ...

Based on their size and function, arteries can be grouped into three types. The elastic arteries are the largest arteries located close to the heart. They ...

Capillaries are the smallest blood vessels, with a diameter of 8 to 10 μm. They comprise a single layer of endothelial cells surrounded by a basement ...

A capillary bed is a network of 10 to 100 capillaries that run between an arteriole and a venule, facilitating microcirculation. The oxygenated blood ...

Venules are tiny veins that collect oxygen-poor blood from the capillary beds. Their diameter may range between 8 and 100 μm. The postcapillary ...

A vein is a blood vessel that carries deoxygenated blood to the heart. Compared to an artery, a vein has a wider lumen that can measure from 0.5 mm to 3 ...

Veins and venules can intrinsically act as blood reservoirs in the human body, holding approximately 64% of the total blood volume at any given ...

An anastomosis is formed by joining two or more branches of an artery or vein to supply blood to a tissue or organ. One of the critical roles of ...

Blood pressure — BP —  is the hydrostatic pressure that blood exerts on the walls of blood vessels, typically measured in mm Hg. In a ...

When blood flows through the vessels, the friction between the vessel walls and blood creates a resistive force called peripheral or vascular resistance. ...

Blood pressure is commonly measured in the brachial artery of the left arm using a sphygmomanometer. It includes a rubber cuff, a rubber bulb for ...

Venous return refers to the volume of blood flowing back to the heart through systemic veins. It is primarily driven by the pressure difference between ...

The pulse is a pressure wave caused by the expansion and recoil of elastic arteries after each systole. It is a vital sign providing insights into the ...

Capillary exchange refers to the movement of substances between blood and interstitial fluid. It occurs through three mechanisms — diffusion, ...

The nervous system regulates blood pressure through baroreceptor and chemoreceptor reflexes. Baroreceptors in the carotid sinuses and aortic arch respond ...

Hormones play a vital role in the regulation of blood pressure. For instance, the renin-angiotensin-aldosterone system, epinephrine and norepinephrine, ...

Autoregulation is the ability of tissues to maintain blood flow based on their metabolic requirements. It ensures optimal blood flow to support both ...

A normal blood pressure is necessary for healthy bodily functions. But, homeostatic imbalances may abruptly change the blood pressure, causing severe ...

Light to moderate physical activity starts a chain of interlinked cardiovascular responses in the body. Initially, the heart rate slightly increases, ...

Systemic circulation involves a complex network of arteries and veins that facilitate the transport of blood between the heart and various organs of the ...

The aorta is the largest artery in the human body, with a lumen diameter of about 2.5 cm and a wall thickness of about 2 mm. It originates from the left ...

The arch of the aorta, which continues from the ascending aorta, begins at the sternal angle and ends between the T4 and T5 vertebrae on the left side. ...

The thoracic aorta is the proximal, 20 cm long section of the descending aorta. Anatomically, the thoracic aorta is positioned to the left of the ...

The abdominal aorta originates from the aortic hiatus in the diaphragm and extends down to the L4 vertebra. It further branches into the visceral and ...

Blood supply to the head and neck is provided by the common carotid arteries and branches of the subclavian artery. The common carotid arteries, which ...

The upper limbs get blood supply through the arteries arising from the subclavian artery. These arteries initially run laterally between the clavicle and ...

Originating from the abdominal aorta, the right and left common iliac arteries and their branches supply the pelvis and lower limbs. At the sacroiliac ...

Systemic veins drain deoxygenated blood from the tissues and return it to the right atrium of the heart. The coronary sinus, located in the posterior ...

Most of the thorax is drained by a system of veins called the azygos system, comprising the azygos, hemiazygos, and accessory hemiazygos veins. The azygos ...

The inferior vena cava is a large vein, fed by many smaller tributaries, that returns blood from the abdominopelvic organs to the heart. Lumbar veins, ...

The internal jugular, external jugular, and vertebral veins are the three pairs of veins that drain most of the blood from the head and neck. The ...

Veins transporting blood from the upper limbs are classified into deep and superficial categories. The ulnar and radial veins are the two prominent deep ...

Blood from the lower limbs is drained by both superficial and deep veins. The deep veins, such as the posterior tibial vein, formed by the union of the ...

The hepatic portal system transports nutrient-rich, deoxygenated blood from the gastrointestinal tract and spleen to the liver. The hepatic portal vein is ...

The pulmonary circulation transports deoxygenated blood from the right ventricle of the heart to the alveoli within the lungs. After exchanging gases, the ...

The development of blood vessels starts outside the embryo on day 15 or 16 in the mesoderm. Two days later, blood vessels start to form inside the ...

Fetal circulation — the circulatory system of a fetus — enables gas and nutrient exchange between the developing fetus and the mother through ...