Which of the following is considered a PRIMARY (not secondary) lymphoid organ?  

  Bronchoconstriction results from relaxation of smooth muscle in the walls of airways.  

  Which of the following features is not common to both lymphatic vessels and circulatory veins?  

  Like blood, lymph flows both to and from the heart.  

  Which lymphoid organ cleanses the lymph… serves predominately in immune surveillance and in filtering lymph?  

  Suppose that following an automobile accident, a broken rib penetrates into the pleural cavity, causing air to accumulate in the space between the visceral and parietal pleura. This condition is known as a….  

  Acidity in human sweat is part of which type of immune system?  

  Put the following terms in the correct sequence of levels according to the structural (or biological) hierarchy.  NOTE:  it starts with POPULATION at the top and ATOM at the bottom.  

  When central chemoreceptors detect a drop in the pH (= becomes more acidic… you’re welcome) of the cerebrospinal fluid (CSF),  

  Air flows out of the body during expiration because…