Digestion and absorption of food and nutrients takes place in the small intestine.
It means than your stomach is hungry/is empty or that it is upset. It could also mean you have gasses passing through you intestiens.
40 including the eye, mouth, esophagus, urethra, stomach, upper intestiens, lower intestines, anus etc.
There are two. "The internal sphincter controls the bladder's opening into the urethra, and the external sphincter (the pelvic muscles) controls the opening of the urethra below the prostate. In women, there is little definition between the internal and external sphincters."-Rosdahl, Caroline, & Kowalski, Mary. (2008). Textbook of basic nursing. 530 Walnut Street, Philadelphia PA 1910: Lippincott Williams & Wilkins.