Which of the following physiologic principles would be considered a function of the somatic nervous system?

A) Proteins:
Proteins are generally too large to diffuse freely across the cell membrane. They require specific transport mechanisms, such as endocytosis or transport proteins, to move in and out of cells. The hydrophilic nature of most proteins further complicates their passage across the lipid bilayer.

B) Enzymes:
Like proteins, enzymes are large molecules that do not freely diffuse across cell membranes. Enzymes, being proteins, also need specialized transport mechanisms or need to be secreted or endocytosed to enter or exit cells.

C) Hormones:
Many hormones, particularly lipid-soluble ones like steroid hormones, can diffuse freely across the cell membrane. These hormones pass through the lipid bilayer due to their hydrophobic nature and bind to intracellular receptors, initiating cellular responses. However, water-soluble hormones (e.g., insulin) typically do not diffuse freely but interact with receptors on the cell surface.

D) Electrolytes:
Electrolytes (such as sodium, potassium, calcium, and chloride ions) are charged particles that cannot pass freely through the lipid bilayer due to the hydrophobic interior of the cell membrane. They require specific ion channels or transporters to move in and out of the cell. Diffusion of electrolytes is facilitated through these channels, but it is not a simple diffusion process as seen with small, uncharged molecules.

A) Inhibit cyclooxygenase that is necessary for prostaglandin synthesis:
NSAIDs primarily work by inhibiting the enzyme cyclooxygenase (COX), which plays a crucial role in the conversion of arachidonic acid into prostaglandins. Prostaglandins are chemicals that promote inflammation, pain, and fever in response to injury or infection. By blocking COX, NSAIDs reduce the production of prostaglandins, thereby decreasing inflammation and alleviating pain and fever.

B) Exert direct actions to cause relaxation of smooth muscle:
NSAIDs do not directly cause the relaxation of smooth muscle. While some other classes of drugs (e.g., bronchodilators) target smooth muscle relaxation, NSAIDs primarily work by reducing the production of prostaglandins, which in turn alleviates inflammation and pain. They do not have a significant effect on smooth muscle tone itself.

C) Suppress prostaglandin activity by blocking tissue receptor sites:
NSAIDs do not block the receptor sites for prostaglandins; rather, they inhibit the cyclooxygenase enzyme, which is responsible for the synthesis of prostaglandins. This reduces the overall production of prostaglandins, rather than blocking their activity at the receptor level.

D) Interfere with neuronal pathways associated with prostaglandin action:
While NSAIDs reduce prostaglandin production, they do not directly interfere with neuronal pathways associated with prostaglandin action. They act primarily by inhibiting the cyclooxygenase enzyme to reduce the synthesis of prostaglandins at the site of injury or inflammation, rather than by modulating specific neural pathways.