1 The bitch has been pushing hard for an hour with no results. 2  A puppy presents rear end first and the head is too large to clear the pelvic bones.  There has been more than two hours between births, but you can still feel puppies inside.
Bronchus / Bronchi / Bronchioles. The airways of the lungs. When a person takes in a breath of air, the air travels through the nose or mouth, into the larynx, then into the trachea, which is the main passageway into the lungs. The trachea divides into a right and left main bronchus.
1 Lungs-these are the balloon-like structures that temporarily hold air in the body. 2  Bronchial tube-the trachea breaks up into these smaller tubes to enter the right and left lungs. 3  Bronchioles-within the lungs the bronchi split into these even smaller tubes which attach to the alveoli.