From Wikipedia-

Anandamide: "The human body synthesizes anandamide from N-arachidonoyl phosphatidylethanolamine, which is itself made by transferring arachidonic acid from phosphatidylcholine (PC) to the free amine of phosphatidylethanolamine (PE).[6][7] Endogenous anandamide is present at very low levels and has a very short half-life due to the action of the enzyme fatty acid amide hydrolase which breaks it down into free arachidonic acid and ethanolamine. Studies of piglets show that dietary levels of AA and other essential fatty acids affect the levels of anandamide and other endocannabinoids in the brain. [8]"

Arachidonic acid: "Arachidonic acid is a polyunsaturated fatty acid that is present in the phospholipids (especially phosphatidylethanolamine, phosphatidylcholine and phosphatidylinositides) of membranes of the body's cells, and is abundant in the brain. It is a precursor in the production of eicosanoids: the prostaglandins, thromboxanes, prostacyclin and the leukotrienes (through enzymes including cyclooxygenase, lipoxygenase and peroxidase). The production of these derivatives, and their action in the body, are collectively known as the arachidonic acid cascade; see Essential fatty acid interactions for details.

Arachidonic acid is freed from phospholipid molecule by the enzyme phospholipase A2. It is also involved in cellular signaling as a second messenger.

Arachidonic acid is one of the essential fatty acids required by most mammals. Some mammals lack the ability to—or have a very limited capacity to—convert linoleic acid into arachidonic acid, making it an essential part of their diet. Since little or no arachidonic acid is found in plants, such animals are obligatory carnivores; the cat is a common example.[2][3] "