Human Circulatory System

Arteries have thicker muscular walls to handle high pressure, lack valves (except at the heart exit), and exhibit pulsatile (jerky) flow. Since all these statements accurately describe differences between arteries and veins, D is the correct choice.

Blood capillaries are composed of a single layer of endothelial cells resting on a basement membrane. They lack the smooth muscle and connective tissue layers found in larger blood vessels to facilitate rapid diffusion.

The splenic artery, which supplies the spleen, is one of the three main branches of the coeliac artery (or celiac trunk). The other branches are the left gastric artery and the common hepatic artery.

The hepatic portal vein is unique because it carries blood from the digestive organs to the liver, where it breaks up into a second capillary bed (sinusoids). This allows the liver to process nutrients and toxins absorbed from the gut.

The carotid arteries are major blood vessels in the neck that supply oxygenated blood to the brain, neck, and face. They are essential for maintaining cerebral perfusion.

The hepatic vein carries blood away from the liver. Since the liver is the site of urea production (via the urea cycle), the blood in the hepatic vein has a high concentration of urea compared to blood entering the liver.

Arteries, including the pulmonary artery, have thicker walls than veins to withstand the pressure of blood being pumped from the heart. Pulmonary veins, like other veins, have thinner walls and contain valves.

Blood from the hepatic artery enters the systemic capillaries, returns to the right atrium, passes to the right ventricle, goes to the lungs, returns to the left atrium, and then to the left ventricle. In a complete circulatory circuit, blood passes through the heart twice (once through the right side, once through the left side).

The hepatic portal vein collects blood from the digestive tract (stomach, intestines, spleen, pancreas) and transports it directly to the liver for processing before it enters the general systemic circulation.

The pulmonary veins are unique because they carry oxygenated blood from the lungs back to the left atrium of the heart, unlike other veins which carry deoxygenated blood.

Veins are used for injections because they have thinner walls, lower pressure, and are generally more accessible than arteries. Injecting into a vein ensures the substance enters the systemic circulation directly.

The right atrium receives blood from three major vessels: the superior vena cava (from the upper body), the inferior vena cava (from the lower body), and the coronary sinus (draining the heart muscle itself).

The hepatic portal vein carries blood rich in nutrients absorbed from the digestive tract directly to the liver. Other veins listed carry deoxygenated blood that has already passed through tissues and lost nutrients.

Arteries carry blood from the heart to various organs of the body under high pressure so they have thick and elastic walls. Veins collect the blood from different organs and bring it back to the heart. The blood is no longer under pressure so, the walls are thin with valves to ensure that blood flows only in one direction.

In arteries the tunica media contains smooth muscle cells & elastic tissue, is thicker than that of veins so it can control and maintain blood pressure.