Anastomoses | Arteries |
Arterioles | Capillaries |
Blood vessels that carry oxygenated blood away from the heart (except pulmonary arteries, which carry deoxygenated blood). | Connections between blood vessels that allow blood to bypass capillary networks, ensuring circulation even if a vessel is blocked. |
The smallest blood vessels where gas, nutrient, and waste exchange occurs between blood and tissues. | Small arteries that regulate blood flow into capillaries through vasoconstriction and vasodilation. |
Veins | Venules |
Endothelium | External elastic lamina |
Small veins that collect blood from capillaries and transport it to larger veins. | Blood vessels that return deoxygenated blood to the heart (except pulmonary veins, which carry oxygenated blood). |
A layer of elastic fibers found in muscular arteries, providing flexibility and recoil. | The innermost layer of blood vessels, composed of simple squamous epithelial cells, which reduces friction and facilitates exchange. |
Internal elastic lamina | Tunica externa |
Tunica intima | Tunica media |
The outermost layer of a blood vessel, made of connective tissue, providing support and anchoring. | A layer of elastic fibers between the tunica intima and tunica media in arteries, allowing for stretch and recoil. |
The middle layer of a blood vessel, composed of smooth muscle and elastic tissue, responsible for vasoconstriction and vasodilation. | The innermost layer of a blood vessel, consisting of endothelium and a thin connective tissue layer. |
Vaso vasorum | Elastic artery |
Muscular artery | Continuous capillary |
Large arteries (e.g., the aorta) with a high proportion of elastic fibers, allowing them to stretch and recoil with each heartbeat. | Small blood vessels that supply the outer layers of large blood vessels with nutrients and oxygen. |
A type of capillary with tightly connected endothelial cells, allowing only small molecules to pass (found in muscles, lungs, and the brain). | Medium-sized arteries with more smooth muscle, allowing them to regulate blood flow through vasoconstriction and vasodilation. |
Fenestrated capillary | Sinusoidal capillary |
Blood viscosity | Colloid osmotic pressure |
Large, leaky capillaries with wide gaps between endothelial cells, allowing passage of large molecules and cells (found in the liver, spleen, and bone marrow). | Capillaries with pores (fenestrations) that allow rapid exchange of fluids and small solutes (found in kidneys and intestines). |
The pressure exerted by plasma proteins (mainly albumin) that pulls water into the blood vessels from the surrounding tissues. | The thickness of blood, which affects its ability to flow; higher viscosity increases resistance and slows circulation. |
Filtration | Hydrostatic pressure |
Mean arterial pressure (MAP) | Net filtration pressure (NFP) |
The pressure exerted by blood against the walls of capillaries, pushing fluid out into the surrounding tissues. | The process by which fluid moves out of capillaries into surrounding tissues due to hydrostatic pressure. |
The difference between hydrostatic and colloid osmotic pressures, determining whether fluid moves into or out of capillaries. | The average pressure in the arteries during one cardiac cycle, ensuring adequate blood flow to organs. |
Pulse pressure | Reabsorption |
Systemic circuit | Pulmonary circuit |
The process of fluid moving back into capillaries from surrounding tissues due to colloid osmotic pressure. | The difference between systolic and diastolic blood pressure, indicating the force of each heartbeat. |
The circulation of blood between the heart and the lungs, where blood is oxygenated. | The part of the circulatory system that carries oxygenated blood from the heart to the body and returns deoxygenated blood to the heart. |
Tissue perfusion | Precapillary sphincters |
Total peripheral resistance (TPR) | Turbulence |
Rings of smooth muscle at the entrance of capillary beds that regulate blood flow based on tissue needs. | The delivery of oxygen and nutrients to tissues via the blood supply. |
Irregular, chaotic blood flow that increases resistance and can contribute to clot formation. | The overall resistance of blood flow in the circulatory system, influenced by vessel diameter, blood viscosity, and vessel length. |
Vascular resistance | Vasoconstriction |
Vasodilation | W4 |
The narrowing of blood vessels due to contraction of smooth muscle, increasing blood pressure and reducing blood flow. | The resistance blood encounters as it flows through vessels, primarily determined by vessel diameter. |
D4 | The widening of blood vessels due to relaxation of smooth muscle, decreasing blood pressure and increasing blood flow. |