The skin is the tissue or organ that covers and protects the human body. It is the largest organ of the human body and serves multiple purposes.
epithelium
adhere to surfaces and form colonies. It also protects them from harmful environmental conditions and helps them to access nutrients. The gel-like substance is often referred to as a biofilm or extracellular matrix.
visceral peritoneum
holocrine glands
Tissues are groups of similar cells that perform a common function. There are four categories of tissues in the human body: epithelial, connective, nervous, and muscle.Epithelial tissue protects your body from moisture loss, bacteria, and internal injury. There are two kinds of epithelial tissues:Covering and lining epithelium covers or lines almost all of your internal and external body surfaces; for example, the outermost layer of your skin and other organs, and the internal surface lining of your lymph vessels and digestive tract.Glandular epithelium secretes hormones or other products such as stomach acid, sweat, saliva, and milk.
The purpose of epithelial tissue is to protect the surfaces of internal organs and the outer surfaces of the skin covering the body.
The internal surfaces such as inside blood vessels and lymph nodes are covered by endothelium and the external surfaces are covered by epithelium. "Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands." (Wikipedia)
It is because cells of epithelial tissues are found covering numerous internal and external surfaces of the body and may also be modified to form glandular structures.
Generally speaking they are the internal and external surfaces of a cone. It is also an indication of the orientation of the object.
Covering surfaces
epithelium
adhere to surfaces and form colonies. It also protects them from harmful environmental conditions and helps them to access nutrients. The gel-like substance is often referred to as a biofilm or extracellular matrix.
Skin is the first physical barrier to external damage. It has alerting system owing to pain and temperature sensations. Body's immune system for any possible threat through orifices or surfaces not covered by skin. The norepinephrine signal of fight, flight, freezing with fear on perception of threat from external physical or emotional sources helps prevent from external damage.
Epithelial tissue coats surfaces in the body.
About of Blood's flow:A fluid flow is classified as being internal or external, depending on whether the fluid is forced to flow in a confined channel or over a surface. The flow of an unbounded fluid over a surface such as a plate, a wire, or a pipe is external flow. The flow in a pipe or duct is internal flow if the fluid is completely bounded by solid surfaces. The flow of liquids in a duct is called open-channel flow if the duct is only partially filled with the liquid and there is an free surface, e.g. the flows of water in rivers and irrigation ditches.
hi the plural is epithelium which means a thin layer of tightly packed cells lining internal cavities, ducts, and organs of animals and covering exposed bodily surfaces, especially in wounds that are healing. hope that helps
visceral peritoneum