Cardio IQ Test: Cardiovascular System Quiz

Veins are thin-walled blood vessels that carry blood to the heart under relatively low pressure. Unlike arteries, which carry oxygenated blood away from the heart under higher pressure, veins transport deoxygenated blood back to the heart. The thin walls of veins allow for the expansion and contraction of the blood vessels as blood flows through them. This low-pressure system helps to prevent the backflow of blood and allows for efficient return of blood to the heart.

Venules are small veins that collect blood from capillaries and deliver it to larger veins. Capillaries are microscopic blood vessels that connect arterioles and venules, allowing for the exchange of oxygen, nutrients, and waste products between the blood and tissues. Therefore, venules and capillaries work together in the circulatory system to transport blood from the smallest blood vessels (capillaries) to larger ones (venules) for further circulation throughout the body.

The tunica intima of the veins is composed of endothelium. The endothelium is a single layer of cells that lines the inner surface of blood vessels, including veins. It acts as a barrier between the blood and the surrounding tissues, regulating the exchange of substances such as oxygen, nutrients, and waste products. The endothelium also plays a role in maintaining blood vessel tone and preventing clot formation. Therefore, it is the correct answer for the composition of the tunica intima of veins.

In adults, all veins except for the pulmonary veins carry deoxygenated blood. This is because the pulmonary veins are responsible for carrying oxygenated blood from the lungs back to the heart. Venous walls are similar to arterial walls but their lumens have greater diameters. The lumen refers to the inner space or opening of a blood vessel, and in veins, it is typically larger than in arteries to accommodate the lower pressure and slower flow of deoxygenated blood.

Veins that are larger than 2 millimeters in diameter have one-way valves positioned in such a way that they can conduct blood against the force of gravity. These valves prevent the backflow of blood and ensure that it flows in one direction, towards the heart. This is important because gravity tends to pull blood downwards, and without the valves, blood would accumulate in the lower extremities. The valves open when blood flows towards the heart and close to prevent backflow, allowing efficient circulation throughout the body.

The outermost and most prominent layer of the veins is called the tunica externa. This layer contains a significant amount of collagen and elastic fibers. These fibers provide strength and elasticity to the veins, allowing them to withstand the pressure and stretching that occurs during blood circulation.

The correct answer is tunica interna, tunica media, tunica externa. Arteries and veins both have three layers, known as tunics. The innermost layer is called the tunica interna, which is made up of endothelial cells and provides a smooth surface for blood flow. The middle layer is called the tunica media, which contains smooth muscle cells and elastic fibers that help regulate blood pressure and control vessel diameter. The outermost layer is called the tunica externa, which consists of connective tissue and provides support and protection to the vein.

The veins have a poorly developed tunica media, which is the middle layer of the vein wall. This layer is composed of smooth muscle and elastic tissue. Due to their poor development, the walls of the veins will collapse when they are empty.

Veins found in the extremities normally contain valves. The extremities refer to the outermost parts of the body, such as the arms and legs. Valves in veins help to prevent the backflow of blood and ensure that it flows in one direction towards the heart. Given that veins in the extremities are responsible for carrying blood back to the heart, it is essential for them to have valves to facilitate proper circulation.

The valves of the veins are usually composed of 2 cusps formed by inward extensions of the tunica interna. They are arranged to permit blood flow toward the heart and not backward in the opposite direction. In other words, they prevent backflow.