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Epithelial tissue. Dr. Amam Ali Amam PhD: Periodontal Disease. The human body is composed of only 4 basic types of tissue. Epithelial tissue. Muscular tissue. Nervous tissue. Connective tissue. They are formed by:. Cells. Molecules of the extracellular matrix.
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Epithelialtissue Dr. Amam Ali AmamPhD: Periodontal Disease
The human body is composed of only 4 basic types of tissue Epithelial tissue Muscular tissue Nervous tissue Connective tissue They are formed by: Cells Molecules of the extracellular matrix
Connective Tissue is characterized by: The abundance of extracellular material produced by its cells.
MuscularTissue is composed of: elongated cells that have the Specialized function of contraction .
Nervous Tissue is composed of: cells with elongated processes that receive, generate and transmit nerve impulses
Epithelial Tissues are composed of: closely aggregated PolyhedralCells very little Extracellular Substance
Epithelialtissue: These tissues exist not as isolated units but rather is association with one another and in variable proportions, forming different organs&systems of the body. Epithelial cells covers or line surfaces of thebody & cavities (eg, skin, stomach, oral cavity, all tubes inside the blood vessels).
The principal Functions of Epithelial tissues are: 1- Covering & lining of surfaces (eg, skin, intestines). 2- Absorption (eg, intestines). 3- Secretion (eg, glands). 4- Sensation (eg, gustative & olfactory neuroepithelium) 5- Contractility (eg, myoepithelial cells)
Epithelial Cells are covering & lining surfaces and cavities of the body (external & internal surfaces). Therefore, everything that enter or leave the body should cross the epithelial sheet.
Relationship between Epithelial Cells (E.C). It’s very strong (firm), they should be continuous Because they are going to ( cover, protect, make the function) as perfect as possible. They communicate because they want to know the function of the other, and to live ( if one cell is underworking then the other cell should raise up their level to cover for it ) or if it died.
Most organs can be divided into 2 components It’s composed of the cells responsible for the main functions typical of the organ 1-Parenchyma 2-Stroma It’s the supporting tissue, it’s made of connective tissue, except in the brain and spinal cord
Forms of Nucleus & it’s location Epithelial Cell nuclei have distinctive shapes: The long axis of the nucleus is always parallel to the main axis of the cell.
Specialization of the cell surface 1- Microvilli. 2- Cilia. 3- Flagella.
1- Microvilli They are found mainly on: 1- the Free cell surface. 2- absorptive cells(lining epithelium of the small intestines & the cells of the proximal renal tubule).
2- Cilia They are cylindrical motile structures on the surface of some epithelium cells.
2 Types of Epithelium according to structure & function 1- Covering Epithelium 2- Glandular Epithelium 3- Pseudostratified 2-Stratified 1-Simple 1-Squamous. 2-Cuboidal. 3-Columnar. 1-Squamous keratinized. 2-Squamous non-keratinized 3-Cuboidal. 4-Transitional. 5-Columnar.
Types of covering epithelium 1-Simple 2-Stratified 3- Pseudostratified
Types of covering epithelium Simple Epithelium Patterns 1-Squamous. 2-Cuboidal. 3-Columnar.
1- Simple Squamous Epithelium Where it’s Located ? • lungs (alveoli). • capillary ((endothelium). • lining of pleural cavity, the pericardium, and the peritoneum. • Bowman's capsule (Kidney). • Blood vessels ((endothelium).
2- Simple CuboidalEpithelium Where it’s Located ? • follicle of thyroid gland • collecting ducts of kidney • salivary glands. • Pancreas. • Ovary. • Uterus. • Lining of intestine. • gallbladder
Types of covering epithelium 3-Simple Columnar Epithelium.
3- Simple ColumnarEpithelium Where it’s Located ? • Gallbladder. • surface epithelium of stomach. • Uterine glands (all phases). • small intestine
Types of covering epithelium 1-Simple 2-Stratified 3- Pseudostratified
Types of covering epithelium Stratified Epithelium Patterns 1-Squamous keratinized. 2-Squamous non-keratinized 3-Cuboidal. 4- Transitional. 5-Columnar.
Stratified Squamous non-keratinized (moist) Where it’s Located ? • oral mucosa • pharynx • esophagus • anal canal • uterine cervix & vagina
Transitional Stratified Epithelium Where it’s Located ? Bladder, Ureters, renal calyces.
Cuboidal Stratified Epithelium Where it’s Located ? • Ducts of sweat glands, • developing ovarian follicles.
Ciliated Pseudostratified Epithelium Maxillary Sinus
Glandular epithelial cells (store & secrete : proteins (eg: pancreas) lipids, ( egsebaceous glands) carbohydrates and proteins, (eg: salivary glands) Mammary glands do all that. Secretes substances from the blood, sweat glands GlandularEpithelium
Unicellular: goblet glands. Multicellular: Exocrine Endocrine Types of glands