Answer the following question with complete details:
 
Give a detailed explanation of the functions performed by epithelial tissues.
Answer variants:
cuboidal epithelium
stratified cuboidal
columnar epithelium
respiratory tract
squamous epithelium
heart
 
a. The inner walls of blood vessels are formed by
 
b. The inner lining of the small intestine consists of -
 
c. Lining of kidney tubules is made up of -
 
d. Epithelial cells with cilia are found in -