Endothelium is what type of epithelium

Protection from mechanical and chemical forces. Correct answer: Protection from mechanical and chemical forces. Explanation : Stratified epithelia are composed of two or more layers of epithelial cells. Which of the following best describes the role of epithelial tissue in the human body?

Possible Answers: Support and connect different types of tissues and organs. Act as a regulatory barrier between two locations in the body.

Correct answer: Act as a regulatory barrier between two locations in the body. Explanation : Epithelial tissue lines the blood vessels, organs, and cavities in the human body. Epithelial cells can be which of the following morphologies? Possible Answers: Cuboidal.

Correct answer: All of these. Explanation : Epithelial cells can be categorized by morphology, or shape. Which of the following is not a function of epithelial tissue? Possible Answers: Muscle contractions. Correct answer: Muscle contractions. Explanation : Epithelial tissue acts as a barrier in the human body. Which of the following best describes the morphology of squamous cells in epithelial tissue?

Possible Answers: They are taller than they are wide. Correct answer: They are wider than they are tall. Explanation : Epithelial cells have three distinct morphologies: squamous, cuboidal, and columnar. Copyright Notice. View AP Biology Tutors. Faith Certified Tutor. Andrew Certified Tutor. Julia Certified Tutor.

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Cells lining the respiratory tract secrete mucous that traps incoming microorganisms and particles. A glandular epithelium contains many secretory cells. Epithelial cells are typically characterized by the polarized distribution of organelles and membrane-bound proteins between their basal and apical surfaces.

Particular structures found in some epithelial cells are an adaptation to specific functions. Certain organelles are segregated to the basal sides, whereas other organelles and extensions, such as cilia, when present, are on the apical surface. Cilia are microscopic extensions of the apical cell membrane that are supported by microtubules.

They beat in unison and move fluids as well as trapped particles. Ciliated epithelium lines the ventricles of the brain where it helps circulate the cerebrospinal fluid. The ciliated epithelium of your airway forms a mucociliary escalator that sweeps particles of dust and pathogens trapped in the secreted mucous toward the throat. It is called an escalator because it continuously pushes mucous with trapped particles upward. In contrast, nasal cilia sweep the mucous blanket down towards your throat.

In both cases, the transported materials are usually swallowed, and end up in the acidic environment of your stomach. Cells of epithelia are closely connected and are not separated by intracellular material. Three basic types of connections allow varying degrees of interaction between the cells: tight junctions, anchoring junctions, and gap junctions Figure 4.

At one end of the spectrum is the tight junction , that are located in the apical region of most epithelial cells. The plasma membranes of adjoining cells are fused at various locations. As a result, intercellular spaces are closed off, preventing movement of substances between epithelial cells. An anchoring junction includes several types of cell junctions that help stabilize epithelial tissues. Anchoring junctions are common on the lateral and basal surfaces of cells where they provide strong and flexible connections.

There are three types of anchoring junctions: desmosomes, hemidesmosomes, and adherens. Desmosomes occur in patches on the membranes of cells. The adhesion molecule, cadherin , is embedded in these patches and projects through the cell membrane to link with the cadherin molecules of adjacent cells. These connections are very strong and are especially important in holding cells together.

Hemidesmosomes, which look like half a desmosome, link cells to the extracellular matrix, for example, the basal lamina. While similar in appearance to desmosomes, they include the adhesion proteins called integrins rather than cadherins. Adherens junctions use either cadherins or integrins depending on whether they are linking to other cells or matrix.

The junctions are characterized by the presence of the contractile protein actin located on the cytoplasmic surface of the cell membrane. The actin can connect isolated patches or form a belt-like structure inside the cell.

These junctions influence the shape and folding of the epithelial tissue. In contrast with the tight and anchoring junctions, a gap junction forms an intercellular passageway between the membranes of adjacent cells to facilitate the movement of small molecules and ions between the cytoplasm of adjacent cells.

These junctions allow electrical and metabolic coupling of adjacent cells, which coordinates function in large groups of cells. Epithelial tissues are classified according to the shape of the cells and number of the cell layers formed Figure 4. Cell shapes can be squamous flattened and thin , cuboidal boxy, as wide as it is tall , or columnar rectangular, taller than it is wide.

Similarly, the number of cell layers in the tissue can be one—where every cell rests on the basal lamina—which is a simple epithelium, or more than one, which is a stratified epithelium and only the basal layer of cells rests on the basal lamina.

Transitional describes a form of specialized stratified epithelium in which the shape of the cells can vary. The shape of the cells in the single cell layer of simple epithelium reflects the functioning of those cells. The cells in simple squamous epithelium have the appearance of thin scales. Squamous cell nuclei tend to be flat, horizontal, and elliptical, mirroring the form of the cell.

The endothelium is the epithelial tissue that lines vessels of the lymphatic and cardiovascular system, and it is made up of a single layer of squamous cells. Simple squamous epithelium, because of the thinness of the cell, is present where rapid passage of chemical compounds is observed. The alveoli of lungs where gases diffuse, segments of kidney tubules, and the lining of capillaries are also made of simple squamous epithelial tissue.

The mesothelium is a simple squamous epithelium that forms the surface layer of the serous membrane that lines body cavities and internal organs. Its primary function is to provide a smooth and protective surface.

Mesothelial cells are squamous epithelial cells that secrete a fluid that lubricates the mesothelium. In simple cuboidal epithelium , the nucleus of the box-like cells appears round and is generally located near the center of the cell. These epithelia are active in the secretion and absorptions of molecules.

Simple cuboidal epithelia are observed in the lining of the kidney tubules and in the ducts of glands. Endothelial cells covering the blood vessel wall can regulate blood flow in blood vessels, which can release NO — the vasodilator factor that promotes blood circulation and helps to control blood pressure. Endothelial cells can also secrete a variety of proteins leading to blood disorders, but involving Hemostatic function. Such as the role in Glomerular internal is to filter the blood.

The epithelial cells that make up the skin protect the subcutaneous tissue from damage, bacterial ingress, dangerous chemicals, and avoid excessive loss of moisture. Epithelial cells of skin will secrete sweat to regulate body temperature if necessary. The epithelial cells that cover the pancreas secrete enzymes to promote digestion. In addition, epithelial cells on the surface of the small intestine absorb nutrients from digestive food. The epithelial cells on the surface of the respiratory tract form mucosa, which can secrete mucus to prevent inhalation of bacteria from entering the lungs with the virus.

Skin, nose, tongue, eyes and other organs exposed to nerve endings on the secretion of specialized epithelial cells, they can identify the sensory stimulation.

In short, the main function of epithelial cells involves the secretion, absorption, protection. Endothelial cells are monolayer structures, and water molecules with oxygen molecules are easily passed through endothelial cells into the tissue surrounding the endothelial cells. In addition, endothelial cells lack packed endothelial morphology, the gap between cells contribute to the passage of liquid and material diffusion.

Epithelial cells have a variety of structures to protect the body from external environmental damage. Epithelial cells are tight integration to each other like the bricks, there is a little gap between the cells.