The tonsils located at the base of the tongue are the

A. Thymus:The thymus is essential for the development and maturation of T lymphocytes, particularly in infants and young children. Removing the thymus at one year of age would severely impair adaptive immunity, leaving the child highly susceptible to infections.

B. Spleen:While the spleen plays a significant role in filtering blood and mounting immune responses, its removal is less immediately catastrophic in a one-year-old than removal of the thymus. Children can survive with partial immune support from other lymphoid tissues.

C. Appendix:The appendix contains lymphoid tissue but is not essential for immune function. Its removal has minimal long-term impact on immunity, even in young children.

D. Lymph node:Lymph nodes contribute to local immune responses, but their removal does not drastically impair systemic immunity. Other nodes can compensate for the loss of individual lymph nodes.

E. Palatine tonsil:Tonsils provide localized immune surveillance in the oropharynx. Removal may slightly reduce immune defense in that area, but systemic immunity remains largely intact.

A. Lymph transport is faster than that occurring in veins:Lymph moves much more slowly than blood in veins. Its movement relies on low-pressure mechanisms rather than a central pump like the heart, so this statement is incorrect.

B. Under normal conditions, lymph vessels are very high-pressure conduits:Lymphatic vessels operate under low pressure. They have thin walls and rely on external forces, valves, and vessel contractions to move lymph, not high internal pressure.

C. Lymph transport depends on the movement of adjacent tissues, such as skeletal muscles:Lymph flow is aided by skeletal muscle contractions, respiratory movements, and rhythmic contractions of smooth muscle in the vessel walls. These mechanisms compress lymphatic vessels, helping push lymph toward the thoracic duct and ultimately the bloodstream.

D. Lymph transport is only necessary when illness causes tissue swelling:Lymph circulation is continuous under normal conditions to maintain fluid balance and immune surveillance. Swelling during illness increases demand, but transport is always required.