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.
These bronchioles give rise to the air sacs in the lungs called the alveoli. The lungs are the largest organs in the lower respiratory tract. The lungs are suspended within the pleural cavity of the thorax. The pleurae are two thin membranes, one cell layer thick, which surrounds the lungs.he lower airways or lower respiratory tract includes the portion of the larynx below the vocal cords, trachea, bronchi and bronchioles. The lungs can be included in the lower respiratory tract or as separate entity and include the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.