19. Alzheimer’s disease in human is associated with the deficiency of(A) dopamine(B) glutamic acid(C) acetylcholine(D) gamma aminobutyric acid

22. Which of the following statements about prostaglandins is true?(A) They are one of the types of target cells(B) They are produced by endocrine glands.(C) They travel throughout the body by circulating in the blood.(D) All of the above are true.(E) None of the above is true.