Body Fluids and Circulation Test - 7

During tricuspid valve regurgitation, as the right ventricle contracts to pump blood forward to the lungs, some blood leaks backward into the right atrium, increasing the volume of blood in the atrium. This enlarges the right atrium which can change the pressure in the nearby chambers and blood vessels.

In earthworms, closed circulatory system is present; thus, sinus is absent.

Acetylcholine increases the heartbeat of neurogenic heart. Such hearts are found in annelids and most arthropods.

Heart block is a disease of heart in which impulses are interrupted in the conducting system of heart at any point. It is caused when the bundle of His does not function properly, due to which the impulses do not reach the ventricle.

During adulthood, spleen is involved in the synthesis of lymphocytes.

Lymph fills the spaces between tissues, between the cells of organs and between cells and connective tissues. Tissue fluid serves as the "middleman" for the exchange between blood and body cells. The lymphatic system collects tissue fluid, and as lymph, the collected fluid combines with the blood to maintain its volume. So, the correct answer is option D.

Myoglobin is an iron- and oxygen-binding protein found in the muscle tissue of vertebrates in general and in almost all mammals. It is related to hemoglobin, which is the iron- and oxygen-binding protein in blood, specifically in the red blood cells.

Sinus venosus is the first chamber in the heart of fish, amphibians, reptiles, which receives blood from the veins and contracts to force the blood into the atrium.

Lymph nodes are oval or bean-shaped bodies placed in the lymphatic vessels. They act as filters and are sites where lymphocytes are formed. The main groups of lymph nodes lie in the neck, axilla, thorax, abdomen and groin.