Question

Mark the odd one in each of the following series
(i) Purkinje fibers, AV bundle, AV valve, SA node.
(ii) Mitral valve, tricuspid valve, semilunar valve, venous valve.
(iii) Thoracic duct, aorta, pulmonary vein, vena cava.

Answer 1

(i) AV valve:

1. The Purkinje fibers are the branches of the bundle of His originating from the AV node.
2. The atrioventricular node (AV node) present in the lower side of the right auricle strengthens the impulses from the SA node.
3. The sino-atrial node (SA node) present near the opening of the vena cava generates impulses for contraction.
4. The atrioventricular valves (AV valves) that including tricuspid and mitral valves prevent the backflow of blood between auricles and ventricles.
5. The Purkinje fibers, AV node, and SA node belong to the node regions, but the AV valves are heart valves.

(ii) Venous valve:

1. The tricuspid valve or right atrioventricular valve located between the right atrium and the right ventricle prevents the backflow of blood from right ventricle to right auricle.
2. The semilunar valve present at the edge of the pulmonary artery prevents flow of blood from pulmonary trunk into the right ventricle.
3. The mitral or bicuspid or left atrioventricular valve located between the left atrium and the left ventricle prevents the flow of blood from left ventricle to left auricle.
4. The venous valve are present in the veins in the limb region of the legs.
5. The mitral valve, tricuspid valve, and, semilunar valve represent heart valves, but the venous valves represent the valves present in the ;eg.

(iii) Thoracic duct:

1. The thoracic duct is a part of the lymphatic system that passes through the neck.
2. The aorta is a pulmonary artery arises from the left ventricle and supplies oxygenated blood throughout the body.
3. The pulmonary vein is a vein that carries oxygenated blood from the lungs to the left auricle.
4. The vena cava is a vein that drains deoxygenated blood from all other organs and fills the right auricle.
5. The aorta, pulmonary vein, and, vena cava represent the blood vessels of blood circulatory system, but thoracic duct is a part of the lymphatic system.