An agent that is smaller than a virus causes scrapie. It is either a protein called a prion or it is another substance closely associated with the prion protein. Scientists still have a lot to learn about the scrapie agent and exactly how it works.
Tissue valves are made with tissues from porcine (pig) heart valves or bovine (cow) cardiac tissue because they function like human heart valves. Once the tissue is removed from the animal, it is chemically treated to preserve the tissue and prevent immulogic reactions once it is placed in a patient.
The epiglottis is a flap controlled by smooth muscles. The heart has smooth muscle tissue lining. The diaphragm is made of smooth muscle tissue.There are no skeletal muscles in the circulatory system.onnective tissue supports, protects, and binds other tissues together. The collagen fibers that are found between connective tissue cells provide strength and flexibility. Some examples of connective tissues are bone, cartilage, blood, and adipose (fat).