Answers: 1.Circulatory system-pumping blood to and from the body and lungs with the heart 2.Digestive system-digestion and processing food with salivary glands, esophagus, stomach, liver, gallbladder, pancreas, intestines, rectum, and anus.
During the tie, the male turns around so the dogs are back to back and can defend themselves. The tie typically lasts 20 to 40 minutes. It may be just a few minutes, and dogs can mate successfully without becoming tied at all. The evolutionary reason for the tie is unknown, but it's assumed that if a male dog is tied to a female, it prevents other males mating with her. Unwanted Mating.
Shoelaces are typically tied off at the top of the shoe using a simple bow knot. Besides securing the shoe, this also takes up the length of shoelace exposed after tightening. The common bow consists of two half knots tied one on top of the other, with the second half-knot looped in order to allow for quick untying.