The chordae tendineae of the AV valves are anchored to the _______ of the ventricles.

A. Glucose:Serum contains glucose similarly to plasma because glucose is a small, soluble molecule that is not involved in the clotting process. Its concentration remains largely unchanged whether the blood is clotted or anticoagulated, allowing energy transport to cells.

B. Albumin:Albumin, the most abundant plasma protein, helps maintain osmotic pressure and transport various substances. It is present in both plasma and serum because it does not participate in clot formation and remains in the fluid after clotting.

C. Nitrogenous wastes:Nitrogenous wastes such as urea, creatinine, and ammonia are dissolved in both plasma and serum. These metabolic byproducts are carried in the blood for excretion by the kidneys, and their presence is independent of fibrinogen or clotting proteins.

D. Platelets:Platelets are cellular fragments responsible for initiating clot formation. While plasma contains platelets, serum is obtained after clotting, which consumes platelets along with fibrin, so serum is essentially cell-free regarding platelets.

E. Fibrinogen:Fibrinogen is a soluble plasma protein crucial for clot formation. When blood clots, fibrinogen is converted into insoluble fibrin, forming the clot matrix. Consequently, serum, which is the liquid portion after clotting, lacks fibrinogen, distinguishing it from plasma.

A. Lymph node:Lymph nodes are important for filtering lymph and mounting immune responses, but their removal does not typically cause severe harm because other nodes can compensate, even in young children.

B. Appendix:The appendix contains lymphoid tissue but is not essential for immune function. Its removal rarely causes significant immunologic compromise at any age.

C. Palatine tonsil:Tonsils contribute to local immune defense in the oral and pharyngeal region, but their removal in young children is usually well tolerated, with other lymphoid tissues compensating.

D. Spleen:The spleen is important for filtering blood and responding to certain pathogens, particularly encapsulated bacteria. While removal increases infection risk, children can often survive post-splenectomy with vaccinations and prophylaxis.

E. Thymus:The thymus is crucial in early life for T lymphocyte maturation and the establishment of adaptive immunity. Removal in a one-year-old would severely impair immune system development, making it much more harmful than thymectomy in adults, whose T cell repertoire is already largely established.