Explain what they are, their functions and where they are found. Then go into detail about two organs, with their functions, what tissues they are made of and where they are found in the body.
Tissues: Tissues are groups of similar cells that have specific functions. In this piece of work I’ll talk about these types of cells:
Epithelial are the lining of internal and external surfaces and body cavities, including tubes/channels (ducts) carrying secretions from glands. Epithelial tissues can be made of several layers of cells (called compound epithelia), or a single layer known as simple epithelia. The lowest layer of cells is attached to the basement membrane for support and connection. Part of the basement membrane is secreted by the epithelial cells. There are nerve supplies to epithelia but they are supplied with oxygen and nutrients from deeper tissues by diffusion. Seeing as they are surface cells, they’re exposed to friction, their capacity for growth and repair is greater than other tissues and this usually occurs during sleep.
Simple epithelia: Simple epithelia cells can be either squamous, cubiodal, columnar or ciliated. Squamous epithelial cells are flat, with each nucleus forming a lump within the centre. ‘squamous’ means ‘scaly’ in reference to flatness of the cells. They fit closely together. As these cells are rather delicate they cannot offer much protection and their main function is to allow materials pass through via diffusion and osmosis. Simple squamous epithelium is found within the walls of:
-Bowman’s capsule of nephrons
Cuboidal epithelial cells are normally cube-shaped with spherical nuclei. They often line ducts and tube and allow other materials to pass through in a similar way to squamous epithelia. They normally occur in glandular tissues making secretions.
They can be found in:
-glands like the thyroid gland and breast tissue.