Monocytes differentiate into large phagocytic cells.

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. A decrease in membrane thickness:Thinner respiratory membranes allow gases to diffuse more rapidly between alveolar air and blood. A decrease in thickness enhances gas exchange rather than slowing it.

B. An increase in alveolar surface area:A larger surface area provides more sites for diffusion, improving the efficiency of gas exchange. This change accelerates, rather than impedes, oxygen and carbon dioxide transfer.

C. An increase in membrane thickness:Thickening of the alveolar-capillary membrane, as occurs in conditions like pulmonary fibrosis or edema, increases the diffusion distance. This slows down the movement of oxygen and carbon dioxide between alveoli and blood, reducing gas exchange efficiency.

D. A decrease in nitrogen solubility:Nitrogen is largely inert and not actively exchanged in the lungs. Changes in its solubility have minimal effect on oxygen or carbon dioxide diffusion, so it does not significantly slow gas exchange.

E. An increase in respiratory rate:A higher respiratory rate enhances the ventilation of alveoli and maintains the concentration gradient for diffusion. This actually promotes faster gas exchange rather than slowing it.