The lymphoid organ that destroys worn-out blood cells is indicated by ________

Connective tissue of the skin is developed from ________.

A. melanocytes B. fibroblasts C. collagen D. fascia

As a platelet plug forms, platelets release

A) collagen. B) serotonin. C) creatine. D) fibrin.

Which of the following is not true of ventricles?

a. are called discharging chambers b. pump blood into the arteries c. have thinner walls than atria d. all of the above are true

Facial muscles are unusual in that they

A. are not involved in movement. B. insert and sometimes originate on skin and connective tissue. C. are not involved in facial expression. D. represent a combination of first-class and second-class lever systems. E. are smooth muscles rather than skeletal muscles.