NANP Board Practice Exam

What begins the arachidonic acid (AA) cascade?

1. Release of AA from cell membrane phospholipids through phospholipase A2 activity

2. Release of EPA from cell membrane phospholipids

3. Production of series 2 prostaglandins

4. Inhibition of COX1 and COX2 enzymes

The correct answer is: Release of AA from cell membrane phospholipids through phospholipase A2 activity

The correct response identifies the process that initiates the arachidonic acid cascade. The cascade begins with the release of arachidonic acid from cell membrane phospholipids, which is facilitated by the enzyme phospholipase A2. This process is crucial because arachidonic acid serves as a key precursor for the synthesis of various eicosanoids, including prostaglandins, thromboxanes, and leukotrienes. When phospholipase A2 acts on membrane phospholipids, it liberates arachidonic acid, setting off a series of enzymatic reactions that produce these important signaling molecules. Understanding this cascade is essential for grasping how inflammatory responses and various physiological processes are regulated in the body. The other options do not initiate the cascade. The release of EPA is related but pertains to a different pathway involving omega-3 fatty acids, while the production of series 2 prostaglandins happens later in the cascade after the arachidonic acid has been released. The inhibition of COX1 and COX2 enzymes results from the actions on the products formed later in the cascade, rather than starting it.