can you descirbe an stratified epithelium to me and tell me where it is located in the body?

Question

i am doing an assignment and can't find any details on it other than it is related to stratified epithelium, but that is of no help! If you can tell me what it does exactly and where it is located in the body of wither a human or an animal! it would be really helpful! thank you! Clare xx

Answer 1

I would like to restrict myself to your query rather than give a book.
Stratified epithelium has two or more layers of cells. The shape in the outer layer determines the type.There are three types of cells:(1)squamous(flat and polygonal cells),(2)transitional(pear shaped cells), (3)columnar( pillar like cells).
Squamous cells of this category are located in: epidermis, mouth(buccal cavity) cornea, conjunctiva, oesophagus, vagina, parts of female urethra.
Transitional cells of this category occur in: pelvis of kidney, ureter, male urethra, bladder.
Columnar cells of this category occur in: parts of pharynx.

Answer 2

1. Stratified Epitheliums

Stratified squamous non-keratinizing epithelium - This epithelium is found covering wet surfaces which receive significant "wear and tear" - e.g. inside mouth, esophagus, anal canal. It is NOT composed of successive layers of squamous cells, but consists of basal columnar, polymorphic, and surface squamous layers (Stratified Squamous non-keratinized 1).

Transitional epithelium - This epithelium lines the expandable tubes and organs of the body - e.g. bladder. When the bladder is full and the membrane is stretched, it looks like stratified squamous non-keratinized epithelium. When relaxed, the surface cells obtain a rounded morphology (Transitional Relaxed 1).

Stratified squamous keratinizing epithelium - This epithelium has the same morphology as stratified squamous non-keratinized, but with the outer layer undergoing a metamorphosis to tough non-living layer of keratin. It will form the outer layer of the skin (epidermis) and be either thin (Stratified Squamous Keratinized 1) or thick (Stratified Squamous Keratinized 2). In these pictures, two distinctive features are observed, a layer of diamond shaped cells possessing keratohyaline granules and the surface keratin layer.

2. Stratified epithelia are those composed of more than one layer of cells. It is important to remember that a stratified epithelium is classified on the basis of the shape of the cells in the TOP LAYER ONLY. Cells in the lower layers may take any shape, and often do.

Stratified squamous epithelium is the most common stratified type. It lines the oral cavity, the anus, the vagina, and several other openings. The lumen of the esophagus is lined with it, too. The external skin is an extensive sheet of stratified squamous epithelium, with specialization for resistance to abrasion.

Answer 3

Stratified epithelium is composed of more than one layer, it may be stratified cuboidal or stratified columnar. The skin is usually a stratified type of epithelium.

Answer 4

Clare, as stated above, in a nutshell: Human skin.

Stratified: More than one layer of cells. The superficial layer is used to classify the layer. Only one layer touches the basal lamina. Stratified cells can usually withstand large amounts of stress.

See link below:

Answer 5

Skin

Answer 6

Structure
Epithelial tissue covers the whole surface of the body. It is made up of cells closely packed and ranged in one or more layers. This tissue is specialised to form the covering or lining of all internal and external body surfaces. Epithelial tissue that occurs on surfaces on the interior of the body is known as endothelium. Epithelial cells are packed tightly together, with almost no intercellular spaces and only a small amount of intercellular substance. Epithelial tissue, regardless of the type, is usually separated from the underlying tissue by a thin sheet of connective tissue; basement membrane. The basement membrane provides structural support for the epithelium and also binds it to neighbouring structures.

Types of Epithelial Tissue
Epithelial tissue can be divided into two groups depending on the number of layers of which it is composes. Epithelial tissue which is only one cell thick is known as simple epithelium. If it is two or more cells thick such as the skin, it is known as stratified epithelium.

Simple epithelium
Simple epithelium can be subdivided according to the shape and function of its cells.

Squamous (pavement) epithelium.
Squamous cells have the appearance of thin, flat plates. The shape of the nucleus usually corresponds to the cell form and help to identify the type of epithelium. Squamous cells, for example, tend to have horizontall flattened, elliptical nuclei because of the thin flattened form of the cell. They form the lining of cavities such as the mouth, blood vessels, heart and lungs and make up the outer layers of the skin.


Simple sqaumous epithelium


Simple Cuboidal Epithelium.
As their name implies, cuboidal cells are roughly square or cuboidal in shape. Each cell has a spherical nucleus in the centre. Cuboidal epithelium is found in glands and in the lining of the kidney tubules as well as in the ducts of the glands. They also constitute the germinal epithelium which produces the egg cells in the female ovary and the sperm cells in the male testes.


Simple cuboidal epithelium


Simple Columnar Epithelium
Columnar epithelial cells occur in one or more layers. The cells are elongated and column-shaped. The nuclei are elongated and are usually located near the base of the cells. Columnar epithelium forms the lining of the stomach and intestines. Some columnar cells are specialised for sensory reception such as in the nose, ears and the taste buds of the tongue. Goblet cells (unicellular glands) are found between the columnar epithelial cells of the duodenum. They secrete mucus or slime, a lubricating substance which keeps the surface smooth.


Simple columnar epithelium


Ciliated Columnar Epithelium
These are simple columnar epithelial cells, but in addition, they posses fine hair-like outgrowths, cilia on their free surfaces. These cilia are capable of rapid, rhythmic, wavelike beatings in a certain direction. This movement of the cilia in a certain direction causes the mucus, which is secreted by the goblet cells, to move (flow or stream) in that direction. Ciliated epithelium is usually found in the air passages like the nose. It is also found in the uterus and Fallopian tubes of females. The movement of the cilia propel the ovum to the uterus.


Ciliated columnar epithelium


Glandular Epithelium
Columnar epithelium with goblet cells is called glandular epithelium. Some parts of the glandular epithelium consist of such a large number of goblet cells that there are only a few normal epithelial cells left. Columnar and cuboidal epithelial cells often become specialised as gland cells which are capable of synthesising and secreting certain substances such as enzymes, hormones, milk, mucus, sweat, wax and saliva. Unicellular glands consist of single, isolated glandular cells such as the goblet cells. Sometimes a portion of the epithelial tissue becomes invaginated and a multicellular gland is formed. Multicellular glands are composed of clusters of cells. Most glands are multicellular including the the salivary glands.


Glandular epithelium

Stratified Epithelium.
Where body linings have to withstand wear and tear, the epithelia are composed of several layers of cells and are then called compound or stratified epithelium. The top cells are flat and scaly and it may or may not be keratinised (i.e. containing a tough, resistant protein called keratin). The mammalian skin is an example of dry, keratinised, stratified epithelium. The lining of the mouth cavity is an example of an unkeratinisied, stratified epithelium.


Stratified epithelium


Functions of Epithelial Tissue
Protection
Epithelial cells from the skin protect underlying tissue from mechanical injury, harmful chemicals, invading bacteria and from excessive loss of water.

Sensation
Sensory stimuli penetrate specialised epithelial cells. Specialised epithelial tissue containing sensory nerve endings is found in the skin, eyes, ears, nose and on the tongue.

Secretion
In glands, epithelial tissue is specialised to secrete specific chemical substances such as enzymes, hormones and lubricating fluids.

Absorption
Certain epithelial cells lining the small intestine absorb nutrients from the digestion of food.

Excretion
Epithelial tissues in the kidney excrete waste products from the body and reabsorb needed materials from the urine. Sweat is also excreted from the body by epithelial cells in the sweat glands.

Diffusion
Simple epithelium promotes the diffusion of gases, liquids and nutrients. Because they form such a thin lining, they are ideal for the diffusion of gases (eg. walls of capillaries and lungs).

Cleaning
Ciliated epithelium assists in removing dust particles and foreign bodies which have entered the air passages.

Reduces Friction
The smooth, tightly-interlocking, epithelial cells that line the entire circulatory system reduce friction between the blood and the walls of the blood vessels.

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