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Histology week 2
Epithelium
| Question | Answer |
|---|---|
| The surface of the epithelium facing the lumen usually is very different from the other surfaces of the epithelium. As a result, epithelia are ____. | polarized |
| Cells involved in absorption of substances from the lumen will frequently utilize ____ to increase the surface area of the apical membrane. | microvilli |
| Microvilli are cylindrical structures consisting of a core of a few dozen tightly-bundled ___ filaments covered by the plasma membrane. | actin |
| Highly specialized absorptive cells, such as those found in the ____ and in the____, will have their entire apical surface densely covered with thousands of microvilli. | A. intestine B. proximal kidney tubules |
| Most microvilli are much shorter than cilia, but a few cells have unusually long microvilli-like structures known as____ | stereocilia. |
| Stereocilia contain a core of ____ filaments. | actin (just as all microvilli) |
| The rhythmic beating of ____ can create currents that move fluid or particles along the surface of the epithelium. | cilia |
| The principal locations where “motile” cilia are found are on the apical surface of cells lining the ____, and the ____. | A. respiratory tract B. oviduct |
| At its base, each cilium is attached to a centriole, known as a ____. | basal body |
| In exocrine secretory cells the ___ part of the cell usually is filled with secretory vesicles. | apical |
| Endocrine cells frequently have secretory vesicles associated with the ___ membrane. | basolateral |
| Functionally and biochemically, the ____ and ____ plasma membranes of epithelial cells usually are similar to each other, and distinct from the ___ plasma membrane. | A. basal B. lateral C. apical |
| The lateral surface has specializations involved with cell-to-cell contact while the basal surface interacts with the ____. | basal lamina |
| ___ is perhaps the only intercellular junction that is unique to epithelium. | zonula occludens (tight junctions) |
| Unlike the zonula adherens and the zonula occludens(which form belt-like bands around the cell), desmosomes form ____ structures | disc shaped |
| Similar to the adherens junction, desmosomes consist of transmembrane proteins that are members of the____ protein family | cadherin |
| While the zonula occludens and zonula adherens are not individually visible in the light microscope, a dark bar or spot, known as the ____, sometimes can be seen at the junction between the apical and lateral membranes in some epithelia. | terminal bar |
| ___ junctions form channels which span the plasma membranes of adjacent cells as well as the intervening intercellular space. | Gap |
| Gap junctions allow small molecules to pass directly from the cytoplasm of one cell into the cytoplasm of adjacent cells, coupling the cells ____ and metabolically. | electrically |
| In gap junctions the _____ aggregate laterally within the plasma membrane to form large patches, which are visualized as gap junctions in the electron microscope. | connexons |
| Separating the epithelial cells from the subjacent tissue is a feltwork-like layer of protein and proteoglycans, known as the _____, which is synthesized and secreted by the _____. | A. basal lamina B. epithelium |
| In the electron microscope, the basal lamina consists of two layers: The lightly-staining layer is the ____, located between the more darkly-staining lamina____ and the epithelial cell plasma membrane. | A. lamina lucida or lamina rara B. densa |
| The basal lamina is too thin to be resolved in the light microscope, but it is frequently associated with connective tissue elements to form a thicker structure called the _____, which CAN be seen in the light microscope. | basement membrane |
| Focal adhesions are junctions which attach the actin cytoskeleton to the ____. | substrate (basal lamina) |
| The transmembrane proteins in focal adhesions are members of the ____family (which are transmembrane proteins involved in attaching cells to the extracellular matrix), instead of the ____ used in the zonula adherens. | A. integrin B. cadherins |
| The transmembrane proteins in hemidesmosomes are ___. | integrins |
| Increase in the basolateral surface area usually is achieved by___ the membrane into a series of ridges or sheets. | folding |
| The enlargement (from folding)of the basolateral membrane is commonly seen in epithelia which utilize_____across the basolateral membrane to move ions or other small molecules across the epithelium. | active transport |
| In general, four different functions can be assigned to epithelia: | A. Protection B. Transepithelial transport C. Movement of secreted material D. Secretion? |
| One way to protect against damage from abrasion or chemical damage is for the epithelium to be composed of ___. | Multiple layers of cells (stratified epithelium) |
| The most exposed epithelia, such as those on the surface of the skin and oral cavity, usually are ____ epithelia | stratified squamous |
| Intermediate filaments and desmosomes provide the ____ needed to keep the cells from being torn apart by exogenously applied forces. | tensile strength |
| Large numbers of intermediate filaments and desmosomes are characteristic of upper layers of ___. | stratified squamous epithelia |
| It is not uncommon for the epithelium to secrete a protective layer of mucus if a stratified epithelium is not compatible with other functions of the epithelium. this is the case in the _____ and _____ and in the ___ tract. | A. stomach B. intestine C. upper respiratory |
| ____ allows damaged cells to be sloughed off and replaced by new cells. | Proliferation |
| Features associated with epithelia involved in transport of substances across the epithelium include:____, ____ and ____. | A. Single layer of cells (simple epithelium) B. Increased plasma membrane surface area C. Cellular machinery for transport |
| Most epithelia specialized for transepithelial transport are simple ___or simple ___ epithelia | A. columnar B. cuboidal |
| In order to accommodate the channels and pumps needed to move molecules across the plasma membrane, there needs to be an increase in the amount of _____. | plasma membrane |
| Increased surface area of the plasma membrane on the apical surface is usually achieved by ____, while ____ achieve this on the basolateral surface | A. Microvilli B. infoldings of the plasma membrane |
| Large numbers of ____, frequently located in the infoldings of the basolateral plasma membrane, provide ATP needed for active transport. | mitochondria |
| ___ vesicles and ____ also are involved with some forms of transepithelial transport | A. Pinocytic B. endosomes |
| The specializations associated with movement of secreted substances along the lumen of the organ include ____ and ____. | A. Cilia B. Myoepithelial cells |
| ____ cells are flattened stellate or fusiform cells which lie between the basal lamina and the secretory/ductal cells. | Myoepithelial |
| ____glands accumulate their secretory product in the lumen of the gland. Contraction of the myoepithelial cells causes expulsion of the secretory product from the lumen of the gland. | Apocrine |
| The ____,____, and _____ will be prominent in epithelial cells specialized for PROTEIN secretion | A. rough endoplasmic reticulum (RER) B. Golgi apparatus C. secretory vesicles |
| ____, _____, and ____ will characterize cells specializing in SECRETION OF LIPIDS such as steroid hormones | A. Smooth endoplasmic reticulum (SER) B. Mitochondria C. lipid droplets |
| ____ are formed by invagination of an epithelium | Glands |
| Epithelium in which all of the cells are in contact with the basal lamina, but only some of them reach the luminal surface is called ___ | Pseudostratified epithelia |
| The shape of the___ usually corresponds to the shape of cell. This can be very helpful when classifying an epithelium, since it can sometimes be difficult to see the boundaries of the cell. | nucleus |
| Some stratified squamous epithelia undergo a differentiation process known as keratinization which involves bundling and cross-linking of ____ and other proteins, and destruction of most organelles, including the ___. | A. keratin filaments B. nucleus |
| _____ epithelium is the only example of an epithelial classification that does not fit the “standard” classification scheme that you need to learn for this lecture. | Transitional |
| _____ is a simple squamous epithelium lining the lumen of a blood vessel | endothelium |
| ____ is a simple squamous epithelium lining a body cavity (peritoneal cavity, pleural cavity, or pericardial sac). | mesothelium |
| Examples of simple squamous epithelium include: the ___lining blood vessels, the mesothelium lining the body cavities, most of the ___ of the lung, and the epithelium cells lining the thin limb of the ___ in the kidney. | A. endothelium B. alveolar epithelium C. loop of Henle |
| Examples of Simple Cuboidal epithelium are found lining the___, the ___ ducts of the liver, and the intercalated ducts of the _____. | A. renal tubules B. interlobular C. salivary glands |
| The epithelia lining the stomach, intestines, gallbladder, and striated ducts of the salivary glands is ____. | Non-ciliated simple columnar epithelium |
| Pseudostratified columnar epithelium contains (at least) two types of cells: _____ and ____. | A. Basal cells B. Principal cells |
| In Pseudostratified columnar epithelium, the ____ frequently are progenitor cells that proliferate to give rise to the other cells of the epithelium. | Basal cells |
| In Pseudostratified columnar epithelium, the ____ are tall columnar cells that extend from the basal lamina to the lumen. | Principal Cells |
| A good example of this type of epithelium is the lining of the nasal cavity, trachea, and bronchi. | Ciliated pseudostratified columnar epithelium |
| A good example of this type of epithelium is the lining of the ductus epididymidis and ductus deferens. | Non-ciliated pseudostratified columnar epithelium |
| The cells lining the ductus epididymidis have ___. | stereocilia |
| This type of epithelium contains multiple layers of cells. The basal cells are columnar or cuboidal, while the most superficial cells are squamous. | Stratified squamous epithelium. |
| Cells in an intermediate layer of a keratinized stratified squamous epithelium contain aggregates, known as ____, of a protein involved in keratinization | keratohyalin granules |
| The best example of a keratinized stratified squamous epithelium is the ____. | epidermis |
| The squamous cells in the outer layers of this type of epithelium contain nuclei. Examples of this type of epithelium include the epithelium lining most of the oral cavity, the esophagus, and the vagina. | Non-keratinized stratified squamous epithelium |
| This type of epithelium is characterized by large superficial cells on a stratified epithelium. This type of epithelium is found only in the urinary tract; examples include the epithelia lining the ureters and bladder. | Transitional epithelium |
| Some epithelia which are not specialized for secretion will contain individual cells which are specialized for secretion known as___. | Unicellular glands. (In this course, individual secretory cells will not be considered as glands, but you should be aware that some authors) |
| The intestinal epithelium is specialized for ____, but within this epithelium are ____ cells which are specialized for the secretion of mucus. | A. transepithelial transport B. goblet |
| Invagination of the epithelium is a mechanism that increases the ___, and therefore the number of epithelial cells (secretory cells), without increasing the volume of the lumen of the organ from which the gland originated. | epithelial surface area |
| Invagination of the epithelium also sequesters the secretory cells in a ____ environment. This is particularly important when considering an epithelium, such as the epidermis, which is exposed to the outside world. | protected |
| the epithelium and lamina propria together form the ____. | mucosa |
| Deep to the lamina propria is frequently another layer of connective tissue known as the ____. | submucosa |
| These glands are located within the wall of the organ from which the gland originated. | Intramural glands |
| Intramural glands can be further subdivided according to the location of the gland within the organ:____, _____ and _____. | A. Intraepithelial glands B. Mucosal glands C. Submucosal glands |
| These are relatively uncommon, but they occur as small clusters of cells which form a secretory acinus within a relatively thick epithelium. | Intraepithelial glands |
| These glands are located within the connective tissue (lamina propria) immediately deep to the originating epithelium. | Mucosal glands (The lumen of the secretory part of the gland may open directly into the lumen of the originating organ or a duct lined by non-secretory cells may connect the secretory part of the gland to the lumen of the originating organ. |
| These glands are located within the submucosa, which is the deeper connective tissue of the organ. The secretory cells of the gland usually are connected to the originating epithelium by a duct. | Submucosal glands. |
| Some glands, such as the liver, are much larger than the wall of the organ from which the gland derived (the liver is an outgrowth of the small intestine). They are called: | Extramural glands |
| Extramural glands have become separated from the wall of the originating organ, remaining connected by a relatively long ___. | duct |
| Large extramural glands are surrounded by their own ___, and usually have their own ____. | A. connective tissue capsule B. blood supply |
| The epithelial cells, which form the secretory acini and ducts, are known as the ____ of the gland. | parenchyma |
| The supporting connective tissue in large extramural glads is known as the ___. | stroma |
| In large glands, the earliest branching divides the gland into ____. | Lobes |
| Usually, each lobe (of a gland) is surrounded by its own ___. | connective-tissue capsule |
| Further branching of the epithelium (in glands) results in subdivision of each lobe into ____. | Lobules |
| ____is used to mean any secretory endpiece regardless of the shape of the secretory endpiece. | Secretory endpiece or secretory acinus |
| For an EXOCRINE gland, the product of the secretory cells is released into the lumen of the _____. | secretory acinus |
| Glands can be characterized according to the presence and arrangement of ____. | ducts |
| During development,____ glands lose their connection with the epithelium from which they originated. | endocrine |
| Endocrine glands secrete their products into the____. | extracellular space (these products diffuse from the extracellular space into the blood) |
| In ENDOCRINE glands, a system of ___ is not present and, in most cases, there is no ___ within the secretory part of the gland. | A. ducts B. lumen |
| ____ glands maintain their connection to the originating epithelium and the secretion from the gland is delivered to the space lined by the originating epithelium | Exocrine |
| The ___ of exocrine glands consists of secretory cells and ducts, although not all exocrine glands have ducts. | parenchyma |
| Exocrine glands can be characterized as ___ or ____. | A. Simple B. Compound |
| In ____ glands either the duct is unbranched, or the gland does not have a duct (i.e., the lumen of the secretory acinus opens directly into the space lined by the originating epithelium). | Simple |
| In ____ glands the duct branches; this is the case for large extramural glands, as well as many smaller glands. | Compound |
| ____ in large glands can be classified according to their location within the gland. | Ducts |
| ____ ducts are located within the lobule. These ducts receive secretions from the lumina of secretory acini and drain into interlobular ducts. | Intralobular |
| ____ ducts are located in the connective tissue between lobules. They receive ecretions from the intralobular ducts and, if the gland has lobes, drain into lobar (or interlobar) ducts. | Interlobular |
| _____ ducts occur in large glands which are divided into lobes. These ducts are located outside of the capsule surrounding the lobe, and each lobar duct usually receives all of the secretion from a lobe. | Lobar ducts or interlobar (The lobar ducts unite to form the main collecting duct) |
| The ______ duct extends from the gland to the epithelium from which the gland originated. | main collecting |
| In these glands, the secretory endpiece is long with a relatively uniform diameter. | Tubular glands |
| In these glands, the secretory cells are clustered around a relatively short lumen. In this case, the secretory endpiece is bulbous or spherical. | Alveolar or acinar glands |
| In these glands the distal part of the secretory endpiece has a tubular shape, but the secretory endpiece begins with a bulbous cap of cells. | Tubuloalveolar or tubuloacinar glands- Usually, the secretory cells forming the bulbous cap are different (in both appearance and secretory product) from the cells lining the tubular portion of the secretory unit. |
| This classification is particularly useful for small mucosal or submucosal glands. | Classification of glands according to the branching/coiling of the secretory endpiece. |
| This classification refers specifically to the arrangement of the secretory part of the gland and not to the arrangement of the ducts . | Classification of glands according to the branching/coiling of the secretory endpiece. |
| The secretory part of the gland can be: a. ____. b. ____, and/or, c. ____. | A. Strghait B. Branched C. Coiled |
| Glands can be classified according to their mode of secretion. Traditionally, three modes of secretion have been recognized: | merocrine, apocrine, and holocrine secretion |
| This is the common type of secretion. It is used to secrete water-soluble macromolecules. In this type of secretion, the membrane of the secretory vesicles fuses with the plasma membrane, releasing the contents of the vesicle into the extracellular space. | Merocrine secretion or eccrine secretion -Most glands utilize this mode of secretion. |
| Depending on the type of secretory product, merocrine glands can be further subdivided into: | A. Serous glands B. Mucous glands |
| Glands that secrete proteins or glycoproteins usually are ___ glands. | serous -The secretory vesicles are smaller and usually more densely staining than those of mucus-secreting cells. |
| ___cells also tend to have more rough endoplasmic reticulum (and consequently, their cytoplasm is more basophilic). | Serous |
| ___ consist of a relatively small protein core to which many long chains of negatively-charged carbohydrate are attached. | Mucins |
| mucins are highly hydrated. As a result, the mucins cannot be tightly-packaged and mucus secreting cells usually have very large ____. | secretory granules |
| Mucus-secreting cells usually have relatively sparse ___ and a well-developed_____. | A. rough endoplasmic reticulum B. Golgi apparatus |
| The nuclei of mucous cells also tend to be more ___ than the nuclei of serous cells. | heterochromatic |
| Cells which secrete by an____ mechanism accumulate the secretory material in vesicles or lipid droplets in a specific part of the cell (e.g., the apex of the cell), and then pinch off that part of the cell. | apocrine |
| Secretion of lipid by the mammary gland and secretion of melanin by melanocytes (pigment cells in the skin) occur by this mechanism. | Apocrine secretion |
| In ___ secretion, the secretory product accumulates within the cytoplasm of the secretory cell, and then the entire cell is sloughed from the epithelium. | holocrine |
| This type of secretion is seen in sebaceous glands: | Holocrine secretion |
| _____ cells do not secrete by any of the three modes of secretion described above | Steroid-secreting |
| Steroid hormones are ___ soluble (and also slightly water-soluble), and can simply diffuse out of the cell. | lipid |
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jsm30417