Which of the following is a component of the lymphatic system?

A. The atrioventricular (AV) valves separate the atria from the ventricles. The right AV valve is called the tricuspid valve, and the left AV valve is the mitral valve. These valves ensure that blood flows from the atria into the ventricles without flowing back. This is the correct answer.

B. The pulmonary valve is located between the right ventricle and the pulmonary artery. It does not separate the atria and ventricles.

C. The aortic valve separates the left ventricle from the aorta and prevents blood from flowing back into the ventricle after contraction. It does not separate the atrial and ventricular chambers.

D. The semilunar valves, which include the pulmonary and aortic valves, are located at the exit of the ventricles but do not separate the atria from the ventricles.

A. Calcium plays a critical role in blood clotting. It is involved in the coagulation cascade and is necessary for the activation of clotting factors that help stop bleeding.

B. Calcium is not involved in acid buffering. This function is primarily carried out by buffers such as bicarbonate in the blood.

C. While calcium does help regulate some functions of cells and tissues, it does not primarily contribute to extracellular osmotic pressure; this is more a function of proteins and other ions.

D. ATP production mainly occurs in mitochondria and is driven by the metabolism of glucose and fatty acids, not by calcium directly. Calcium does, however, play a role in cellular processes like muscle contraction.