Basic Tissue Types (Module 1) Flashcards
What are the 4 basic tissue types?
Epithelium, connective, muscle and nervous tissue
Lining of the blood or lymphatic vessels may also be termed ____________ and those of the serous body cavities may be termed __________________.
Endothelium, Mesothelium.
Epithelial tissues are supported by a ___________ ___________.
Basement Membrane
Muscle and nervous tissue have a similar structure that is often called the _________ _________.
External Laminae
Provide the type of junction with the 3 examples below:
- Provide mechanical strength
- link cells to form an impermeable barrier
- allow direct communication between cells
- anchoring junctions
- occluding junctions
- communication junctions
List 3 types of layers of cells and 3 types of cell shape
- simple epithelium
- stratified epithelium
- pseudostratified epithelium
- squamous-flattened
- cuboidal - height and width are similar
- columnar-height is at least twice the width
This is composed of flattened, irregularly-shaped cells that form a continuous surface. They are found lining surfaces involved in the passive transportation of either gases or fluids. They may also be found lining the pleural, pericardial and peritoneal cavities.
Simple squamous epithelium.
This is an intermediate form between the squamous and columnar types. In a section perpendicular to the basement membrane, the cells appear square or cuboidal. They are usually found lining small ducts or tubules, which may have excretory, secretory, or absorptive type functions. Examples of these would be the small collecting ducts of the kidney, salivary glands, and pancreas.
Simple cuboidal epithelium.
This epithelium is similar to cuboidal except that the cells are taller and appear columnar in sections cut at right angles of the basement membrane. The height of the cells may vary from low to tall depending on site and or function. Nuclei may be located at the base, center, or apex. They are most often found on highly absorptive or secretory surfaces. A good example is the mucosal lining of the small intestine, where both luminal digestion and absorption occur. They may also be found in the stomach and gall bladder.
Simple columnar epithelium.
these are columnar cells with the surface specialization of cilia. The cilia are motile projections from the luminal surface. The action of the cilia will propel a fluid or minute particle over the epithelial surface by beating in synchronic rhythm with adjacent cells. An example is the oviduct or fallopian tube found in the female reproductive tract, in this case, the fluid current that the cilia generates, propels the ovum or egg from the ovary to the uterus.
Simple columnar ciliated epithelium
These cells appear, in section, to have more than one layer of cells. But, becuase all of the cells rest on the basement membrane, even though they all do not reach the luminal surface, it is an example of simple epithelium. the nuclei are present at different levels and create the illusion of cellular stratification. These cells are mainly confined to the larger airways of respiratory system. For this reason they are termed respiratory epithelium.
Pseudostratified columnar ciliated epithelium.
This consists of a variable number of layers of cells, which undergo morphological and functional transition from the cuboidal basal layer to the extremely flattened outer surface layers. The cuboidal undergo regular mitotic divisions, so cells are continually rising to the outer surface. As this occurs, the cells will first maturate and then degenerate as they move farther away from the source of nutrition proveded by the connective tissue below the basal layer and basement membrane. The degenerate surface of cells are sloughed continuously and replaced by deeper layers. The rate of mitosis in the basal layer normally equals the rate of cells lost at the surface. It can withstand moderate abrasion, but not desiccation. This type of epithelia is found lining the oral cavity, pharynx, vagina, and areas that are subject to minimal abrasion and that are kept moistened by glandular secretion.
Stratified squamous epithelium
During the maturation process, the epithelium undergoes a process called keratinization. This results in the formation of a tough, non-cellular surface layer consisting of protein, keratin and the remnants of degenerated epithelial cells. The skin is the most common example.
Stratified squamous keratinizing epithelium.
This epithelium consists of two or three layers of cuboidal cells. It is mainly confined to the lining of the larger excretory ducts, such as in the salivary glands, pancreas, and sweat glands. The stratified epitheium provides a bit more robust lining than the simple epithelium found in smaller ducts.
Stratified cuboidal epithelium
This is a relatively rare type of epithelium. It consists of two layers of columnar cells and is found in the ocular conjunctiva and the largest ducts of salivary glands and may also be found in parts of the urethra.
Stratified columnar epithelium
This is a form of stratified epithelium that is highly specialized to accomodate a great deal os stretching and to withstand the toxicity of urine. It is almost exclusively confined to the urinary tract. In the non-distended state the epithelium appears to be four to five cells layers think, and basal cells are cuboidal, polygonal or dome shaped. When stretched, the epithelium appears only two to three layers think with extremely flattened intermediate and surface layers.
Transitional epithelium.
Glands possessing tubular secretory units
Tubular
glands that possess sac-like secretory units, appearing grape like and somewhat spherical
Acinar or alveolar
Glands that possess a combination of tubular and alveolar or acinar secretory units
Tubuloacinar
Glands that produce water secretions that may contain enzymes
Serous
