hydrochloric acid and other digestive enzymes to break down food. Food moves from the stomach into the small intestine. The first part of the small intestine is the duodenum. As food moves through the duodenum, it mixes with bile, a fluid that neutralizes stomach acid and emulsifies fat. The pancreas releases enzymes that aid in digestion so that nutrients can be broken down and pass through the intestinal mucosa into the blood and travel to the rest of the body. The pancreas doesn't produce starch processing enzymes because cats don't eat a diet high in carbohydrates. Since the cat digests low amounts of glucose, the pancreas uses amino acids to trigger insulin release instead. Food then moves on to the jejunum. This is the most nutrient absorptive section of the small intestine. The liver regulates the level of nutrients absorbed into the blood system from the small intestine. From the jejunum, whatever food that has not been absorbed is sent to the ileum which connects to the large intestine. The first part of the large intestine is the cecum and the second portion is the colon. The large intestine reabsorbs water and forms fecal matter. There are some things that the cats are not able to digest. For example, cats clean themselves by licking their fur with their tongue, which causes them to swallow a lot of fur. This causes a build-up of fur in a cat's stomach and creates a mass of fur. This is often thrown up and is better known as a hairball. The short length of the digestive tract of the cat causes cats' digestive system to weigh less than other species of animals, which allows cats to be active predators. While cats are well adapted to be predators they have a limited ability to regulate catabolic enzymes of amino acids meaning amino acids are constantly being destroyed and not absorbed. Therefore, cats require a higher protein proportion in their diet than many other species. Cats are not adapted to synthesize niacin from tryptophan and, because they are carnivores, can't convert carotene to vitamin A, so eating plants while not harmful does not provide them nutrients. Genitalia Female genitalia In the female cat, the genitalia includes the uterus, the vagina, the genital passages and teats. Together with the vulva, the vagina of the cat is involved in mating and provides a channel for newborns during parturition,