Chitin is a primary component in the exoskeletons of arthropods and crustaceans and is also found in the cell walls of fungi. It's a polysaccharide, and it's excreted by the epidermal cells in arthropods.
Definition & Facts. Hemorrhoids, also called piles, are swollen and inflamed veins around your anus or in your lower rectum. External hemorrhoids form under the skin around the anus. Internal hemorrhoids form in the lining of the anus and lower rectum.
Definition of hemorrhoid. Hemorrhoids (Piles) are blood vessels located in the smooth muscles of the walls of the rectum and anus. They are a normal part of the anatomy and are located at the junction where small arteries merge into veins.