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Karteikarten von kawthar bazzoun, aktualisiert more than 1 year ago
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| Frage | Antworten |
| four types of tissue | -epithelium -connective tissue -muscle tissue -nervous tissue |
| two types of epithelium | -covering epithelium ( epithelia that covers other tissues ) -glandular epithelium ( epithelia that has a secretory function ) |
| definition of epithelium 5 | - epithelial tissues are composed of cells that are tightly packed together -epithelium is formed by polarized cells, closely juxtaposed - their cohesion is insured by different adhesion junctions - they have one or more common physiological functions -rests on a basal membrane that separates it from a connective tissue |
| characteristics of covering epithilium 4 | -formed by on or more layers of epithelial cells closely juxtaposed (sometimes with non-epithelial cells) -they rest on a connective tissue through a basal lamina -they are inervated and non-vascularized (blood vessels of the underlying connective tissue do not cross the basal lamina) - have great capacity of regeneration |
| what does the epithelia cover? | - the surface of the body ( skin / epidermis ) -natural internal cavities : . closed cavities ( cardiovascular cavities / endothelium ) & ( serous cavities / mesothelium ) . open cavities ( airway, digestive tract, urinary tract, etc... / mucosal epithelium ) |
| four charecteristics of the epithelial cell | 1- cohesion 2- epithelial morphology ( shape ) 3- polarity 4- presence of intermediate filaments of cytokeratin in their cytoplasm |
| cohesion of epithelial cells | it has adhesion molecules and specialized junction systems that attach the epithelial cells and mantain the cohesion between the epithelial cells and the basal lamina |
| epithelial morphology ( epithelial cells ) | the cells have three shapes; they are either - squamous - cuboidal - columnar |
| presence of intermediate filaments of cytokeratin in the cytoplasm ( epithelial cells ) | cytokeratins are a specifity of epithelial cells |
| polarity of the epithelial cells | - assymetrical distribution of components of the cytoplasm - assymetrical distribution of the components of the plasma membrane ( proteins, enzymes and receptors ) |
| the epithelial cell has three distinct domains | -lateral domain -apical domain -basal domain |
| apical domain of the epithelial cell 3 | -this domain is in contact with the exernal environment of the lumen of the cavities of the organ -it's the most specialized domain ( contains most of the protein specific for the function of the organ ) -it has membrane specializations (cilia and microvilli ) |
| lateral domain of the epithelial cell 3 | -it designates the surfaces that are apposed to neighboring cells -it contains most of the proteins required for fundemental processes common to all cells - there are anchoring and adhering junctions in this domain |
| basal domain of the epithelil cell 2 | - it rests on the basal lamina -hemi-desmosomes and focal adhesion points are observed |
| basement membrane or basal lamina 3 | -participates to the polarization of epithelium -plays a mechanical role by ensuring the cohesiom between the latter and the underliying connective tissue -it plays a role in the exchange and filtration process and in the control of cellular metabolism |
| classification of the covering epithelium 3 | epithelial cells are classified according to three structural criteria - number of cell layers -shape of the cells -specialization at the apical pole |
| properties of covering epithelia 2 | - renewal of epithelia (epithelial cells are exposed to wear and aging and a limited life span. their renewal is ensured by proliferation of stem cells or replacement cells ) - permiability of epithelia ( the basal lamina acts as a selective filter ) |
| definition of glandular cells | glandular cells are epithelial cells with secretory functions. ( the secretory products are stored in the secretory vescicles, and then released on demand ) |
| histogenesis of glands | glandular epithelia results from the differentiation of some embryonic covering epithelia that bud to form a cellular mass. this mass enters into the underlying mesenchyme, it cans then : -maintain the contact with the covering epithelium ( exocrine gland ) -become detached from the covering epithelium ( endocrine gland ) |
| classification of glandular epithelium 3 | -exocrine glandular cells -endocrine glandular cells -amphicrine glands |
| definition of exocrine glands | glands that discharge their secretory products in the externalenvironment or in a natural cavity in continuity with the external environment |
| exocrine cells distinguish two poles | -apical pole ( poor in cell organelles and stores the elaborated products before their secretion ) -basal pole ( rests on a basement membrane thats eparates the glandular epithelium from the connective tissue ) |
| what are contractile myoepithelial cells | they are sometimes located between the secretory cells and the basal lamina; their contraction helps in the excretion of secreted product. |
| classification of exocrine glands according to the number of cells 2 | -unicellular ( goblet cell, they produce mucus that lubricates and protects the surfaces of systems such as the digestive tract, the respiretory tract and etc... ) -multicellular (comprise a secretory part and an excretory canal, enveloped by a stroma of connective tissue ) |
| classification of the exocrine glands according to the excretory duct and the form of the secretory portion 4 | -acinous glands ( simple cinar / compound acinar ) -tubular glands ( simpe tubular / simple branched tubular / simple coiled tubular / compound tuular ) -alveolar glands ( simple alveolar / sebaceous gland ) - mixed ( tubulo-acinar glands , tubulo alveolar glands ) |
| classification of the exocrine gland according to the nature of the secretory product 2 | -serous gland ( secretory product is an enzymes of fluid consistency ) -mucous glands ( secretory product is mucus pr mucins ) -mixed glands ( sweat glands, sebaceous glands ) |
| description of serous cells | -round nucleus -cytoplasn is dark with granulations -narrow barely visible lumen -basal pole rish in RER and mitochondria -golgi apparatus very developed -they are vesicles limited by a membrane - contains enzymes ( either active or in the form of precursors ) |
| description of mucous cells | -large -cytoplasm filled with mucigenic grains -cytoplasn is clear -nucleus is flattened and pushed back to the basal pole with the rest of the organelles -wide and irregular lumen |
| modes of excretion 3 | -merocrine mode -apocrine mode -halocrine mode |
| description of merocrine mode | -most common -the cells produce secretions and they reject them externally by exocytosis -the cell integrity being respected |
| description of apocrine mode | -the secretory product is gradually accumulated at the apical pole -the superficial portion of the cell is detached in the form of a large vacuole -the cell integrity being respected |
| description of holocrine mode | - the secretory product complety fills the cytoplasm the cell then undergoes degeneration which results in the rupture of its membrane - release of accumulated product |
| definition of endocrine glands | an endocrine glandular cell is capable of synthesizing, storing and secreting into the internal medium via the blood stream without an excretory duct, a substance called hormone (chemical messenger) will act on receptors of target cells. |
| classification of endocrine glands according to the morphology 3 | -vesicular glands (vesicles or spherical follicles between nnective tissues and vessels) -reticular glands (the glandular cells form cords with separated by fine connective tissue that are crossed by vessels) -diffuse glands (either grouped into islets or scattered in an epithelium) |
| classificaton of the endocrine clands according to the type of hormone secreted 4 | -steroid secreting endocrine cells -thyroid hormone secreting cells -peptides secreting endocrine cells -amino acids derivative endocrine cells |
| classification of the endocrine glands according to the mode of action of the receptor | -steroid and thyroid act on an intracytoplasmic or intranuclear receptor -peptides and biogenic amines bind on a membrane receptor that will act on a metabolism of the cell via a second messanger |
| definition of amphicrine glands | glands that are both exocrine for some products and endocrine for others |
| classification of amphicrine glands | -homotypic amphicrine glands ( formed by a sinlge type of both endo and exo cells ) -heterotypic amphicrine glands (two type of cells are found in the parenchyma, some are exo and others and endo) |
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