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 muscle tissues make up the heart. The muscle tissues have to pump the blood, and fibrous tissue that are made up of the valves. The three tissues that are in the heart are the epicardium, myocardium, and endocardium. The epicardium is the top layer of the heart.It is really made up of two layers.est Answer: I believe that the heart is made up of muscle tissue, epithelial tissue, and nervous tissue, but I'm not sure.. You are correct, but missing one: The heart is made up of CARDIAC MUSCLE (there are three distinct tyes of muscle tissue: skeletal, smooth and cardiac).