Ti Tissues sues Dr.shatarat 1 6/15/2013 د.تارطشلا دجما
Types Tissues are classified into 4 types according to their structure and function: 1. Epithelial tissues 2. Connective tissues 3. Muscular tissues 4. Nervous tissue Dr.shatarat 6/15/2013 2 د.تارطشلا دجما
1. Epithelial tissues Major functions: 1.Act as a selective barriers that limit or aid the transfer of substances into and out the body. 2.Produce secretions on their free surfaces. Dr.shatarat 6/15/2013 3 د.تارطشلا دجما
1-Cellularity 2-Specialized contacts (Packed cells) may have junctions for cells are in close contact with both attachment and each other with little or no communication intercellular space between them 3-Polarity Epithelial tissues always have an apical and basal surface 4-Avascular nutrients must diffuse from near by connective tissue to reach the epithelial cells 6-Regeneration epithelial tissues 5-Innervated have a high capacity for High risk of cancer regeneration Dr.shatarat (Healing of wounds?) 6/15/2013 د.تارطشلا دجما 4
Three types of junctions What is the function of Gap Junctions? Gap junctions serve as passageway between two adjacent cells by allowing small molecules move directly between neighboring cells Dr.shatarat 6/15/2013 د.تارطشلا دجما 5
Classification of epithelial tissue First name of tissue indicates number of layers Simple – Cells arranged in one layer. 1- According to the number of layers, epithelium is Stratified – more than one layer of cells divided into: 1- Simple at the apical (apex / Top) surface 2-Stratified Dr.shatarat 6/15/2013 6 د.تارطشلا دجما
Last name of tissue describes the shape of the cells A - Squamous cells (flat): Are thin, like a plate. 2- According to the B-Cuboidal cells: shaped like cubes shape of each cell, the epithelium is divided into: 1-Squamous 2- Cuboidal 3-Columnar C-Columnar cells: like columns. Dr.shatarat 6/15/2013 7 د.تارطشلا دجما
When we combine the 2 characters (cell shapes and the number of layers), epithelial tissue has the following types: I. Simple epithelium simple epithelium a. Simple squamous. b. Simple cuboidal. c. Simple columnar (nonciliated and ciliated) d. Pseudostratified columnar (nonciliated and ciliated) Dr.shatarat 6/15/2013 8 د.تارطشلا دجما
Functions: A. Simple squamous epithelium Filtration Diffusion Formed of a single layer of flat cells and can be found in: Secretion 1 -Mesothelium: it is a simple squamous epithelium that covers body’s cavities : A- Peritoneum B- Pleura C-Pericardium Dr.shatarat 6/15/2013 9 د.تارطشلا دجما
2 - Endothelium: lining the inner surfaces of the heart and blood vessels 3-Alveoli of lungs 4-Renal corpuscles Dr.shatarat 6/15/2013 د.تارطشلا دجما 10
B. Simple cuboidal Formed of a single Layer of cube-shaped cells. Locations: Line kidney tubules. Surface of ovary. Ducts of pancreas. Functions: Secretion Absorption. Dr.shatarat 6/15/2013 11 د.تارطشلا دجما
C. Simple columnar nonciliated • Form of single layer of nonciliated column like cells. location: lines Gastrointestinal Tract . • • Functions: High capacity of secretion and absorption. Dr.shatarat 6/15/2013 12 د.تارطشلا دجما
D. Simple columnar ciliated Formed of a single layer of ciliated column like cells with Goblet cells in between. lines Bronchioles of lung Locations: • lines Uterine tubes • Dr.shatarat 6/15/2013 13 د.تارطشلا دجما
E.Pseudostratified columnar Pseudostratified epithelium: ( pseudo= false) • Tissue appears to be several layers but is really a single layer. • Cells nuclei lie at different levels and cells appear to have multiple layers. • All its cells rest on the base but not all of them reach the surface. Dr.shatarat 6/15/2013 14 د.تارطشلا دجما
1. Ciliated: Form of cells with cilia and Goblet cells. • Locations: Lines airways of most of upper respiratory tract . • Functions: Secretes mucus that traps foreign particles. 2.Nonciliated: Contains cells without cilia and lack goblet cells. Locations: Lines larger ducts of many glands & epididymis . Functions: Absorption and protection. Dr.shatarat 6/15/2013 د.تارطشلا دجما 15
II. Stratified epithelium Types: a. Stratified squamous • keratinized • Nonkeratinized. b. Stratified cuboidal epithelium. c. Stratified columnar epithelium. d. Transitional epithelium. Dr.shatarat 6/15/2013 16 د.تارطشلا دجما
A-Stratified squamous epithelium • Forms of several layers of cells. • Cells in apical layer and some layers deep to it are squamous (Flat). • Cells move gradually from deep to superficial away from blood vessels then die and slough (fall off). • Found mainly in places subject to attrition (wear and tear) as skin, mouth, esophagus, vagina ). Two types: • Keratinized (dry). • Nonkeratinized (wet). Dr.shatarat 6/15/2013 17 د.تارطشلا دجما
Keratinized stratified squamous : • Covers dry surfaces such as epidermis of skin (superficial layer of the skin). Form tough layer of keratin (tough protein) between surface cells. • Functions: Protect skin and underlying tissues from heat, microbes, chemicals and water loss. Dr.shatarat 6/15/2013 18 د.تارطشلا دجما
Nonkeratinized stratified squamous • Surface layers contain small amount of keratin and always wet. • Location: Lines wet surfaces as Mouth and Esophagus . • Function: Protection against scratch, water loss, ultraviolet radiation, and foreign invasion. • Both types form first line of defense against microbes. Dr.shatarat 6/15/2013 19 د.تارطشلا دجما
D.TRANSITIONAL EPITHELIUM • Show variable appearance. • The form of these cells changes according to the degree of distention of the organ. • Locations: Urinary bladder, ureter. • Functions: Allow the organ to stretch and protection from rupturing. Dr.shatarat 6/15/2013 20 د.تارطشلا دجما
B. Glandular Epithelium • A gland may consist of a single epithelial cell or a group of cells adapted for secretion. • Normally found as: – Unicellular glands as Goblet cells. – Multicellular glands group of cells as Salivary glands. • All glands of the body are classified into: – Exocrine (Exo=outside, crine=secretion): Secrete substances onto a surface by ducts. – Endocrine : Secrete hormones into the blood. – Mixed (exocrine and endocrine): e.g.. Pancreas Dr.shatarat 6/15/2013 21 د.تارطشلا دجما
Functional classification of exocrine glands Based on the releasing mode of their secretions and whether the secretion is a product of a cell or consists whole or a part of the cell they are divided into: 1-Merocrine glands ( mero= a part): • Secretions are released via exocytosis. • Most exocrine glands of the body are merocrine glands. 2-Apocrine glands ( apo= from): • Secretion collected at the apical part of the cell then pinched off by exocytosis. 3-Holocrine glands ( holo= entire): • Secretion collected in their cytosol. When cell matures, it ruptures and becomes the secretory product. e.g. sebaceous gland. Dr.shatarat 6/15/2013 22 د.تارطشلا دجما
Recommend
More recommend
