BIOL 315 1st Edition Lecture 5 Outline of Last Lecture I. EmbryologyOutline of Current Lecture I. Introduction to TissuesII. The Kinds of TissuesIII. EpitheliumIV. GlandsCurrent LectureI. Introduction to Tissuesa. Tissue: a group of cells with similar functions (and similar structure)b. Not only consists of cells, non-cellular material is also present in tissues, occupying the space between the cells: extracellular materiali. Made of fluid, ions, proteins, and sugarsii. Over half of the mass of our bodyc. Cell: a living unit with a plasma membrane, cytoplasm, and nucleus (nothing else)II. The Kinds of Tissuesa. 4 basic classes of tissues in the adult human, make up all organs of the bodyi. Epithelium (and glands)ii. Connective tissue1. Connective tissue proper2. Bone 3. Cartilage 4. Bloodiii. Muscle tissueiv. Nervous tissueIII. Epitheliuma. Definition: made up of sheets of cells that cover surfaces, or line cavities, on or in the bodyi. Example) epidermis of our skinii. Lumen: the cavity of a hollow organThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Cells are joined closely to one anotheri. Very little extracellular material between the cellsc. Function: i. Interfaces between 2 distinct kinds of environmentsii. Role relates to their position at interfacesiii. All involved in sensory reception iv. Some protective, move substance across body surfaces, absorbing nutrientsv. Always underlain by connective tissue propervi. Blood vessels do not enter epithelia, but nerves do1. Therefore, innervated not vascularvii. Cells tend to be short lived , dividing rapidly viii. Accumulate genetic mistakes, give rise to cancer1. Breast, lung, skin, colon, and bladder cancers all derive from epithelial tissuesd. Classification: i. First name: number of cell layers they contain1. Simple: only one layer of cells2. Stratified: more than one layer of cellsii. Second name: shape of the component cells1. Squamous: flat cells2. Cuboidal: cells as tall as they are wide3. Columnar: tall cellsiii. Simple cuboidal and simple columnar epithelia  active functions1. Secretion, pumping ions, excreting waste molecules, absorbing nutrients2. Simple squamous too thin to perform such functionsiv. Psuedostratified columnar epithelium1. Appears to have more than one layer of cells, but it really doesn’t 2. Nuclei lie at different levels, but all cells touch the connective tissue at the base v. Cilia1. Lash-like extensions of the apical cell surface2. Beat back and forth to move fluids3. When present the tissue is ciliatede. Special Structures Associated with Epithelia: On, Between, and Below Epithelial i. Epithelial tissue has polarity: the top surface of the cells differ from their lateral surfaces and from the basal surface 1. Structures on the apical surface of epithelia: microvilli and ciliaa. Part of surface cells, projectionsb. Can be seen with SEMc. Microvilli: moving , peg-like projections, occur on surfaces of moist epithelia , increase absorptive-surface area,always present where mucus is secreted, and may functionto anchor mucous layer to these surfaces, stiff- protecting the surface against micro-abrasiond. Cilia: not as common as microvilli, beat to propel fluid, 9 pairs surrounding a 10th pair, each pair has dyein arms that grab and move along a neighboring pair to bend the cilium,resemble centrioles2. Lateral cell features: cohesion between epithelial cellsa. Cell junctions: joins epithelial cells togetherb. Desmosome: “spot weld” scatter all around the cell membrane, forming strong bonds c. Junctional complex: towards the apex, series of lateral junctions, occurs in all types of epithelial except simple sqamousi. Includes 3 structures: 1. zonula occludens : long bands extending around the circumference of each cell, sticky belt2. zonula adherens: tight junction, long band extending around the circumference of eachcell, membranes of adjacent cells are fused and prevent molecules outside the epithelium form using the intercellular space to cross epithelium3. desmosomed. gap junction (nexus): tiny protein tubes run across the intercellular space to provide channels connecting the cytoplasms of adjacent cells , allow direct flow of small molecules 3. The basal surface: basal laminaa. Basal lamina: at base of all epithelia is a thin sheet, consists of various protein molecules, capillaries must diffuse through this on way to epithelial cells, acts as a selective filter, serves as a scaffold for epithelial regenerationIV. Glandsa. Glands: made of epithelial secretion cellsb. Most secretions= proteinsc. Gland cell makes and protects and secretes its protein product:i. Protein made in RERii. Moved to Golgi Apparatus in vesicles budded from the RERiii. In the GA, the product concentrated and modifiediv. Secretory granules containing the product are budded off of the Golgiv. Granules stored in the cytoplasm, until stimulated to secretevi. product is released as granules fuse with apical cell-membrane = exocytosis (“out of the cell”)d. can be divided into endocrine or exocrine glandsi. endocrine glands: secrete hormones into the blood and have no ducts1. hormones: messenger molecules that travel through the bloodstream and are taken up my specific cells elsewhere, and signal a responseii. exocrine glands: secrete their products onto the body surfaces or into hollow organs, most have ducts1. examples: milk glands, salivary glands, sweat glands, oil glands in the skin2. classified according to whether they are single cells (unicellular glands) or composed of many cells (multicellular glands)a. goblet cells: type of mucous secreting cell, only important unicellular glands3. exocrine glands with ducts are further classified by the nature of their duct a. Simple gland: one in which the duct is not branchedb. Compound gland: has a branched duct4. Exocrine glands with ducts are further classified by the shape of their secretory unitsa. Tubular: long tubes at the end of the duct system b. Acinar or alveolar: if the secretory unit are hollow spheres5. The two most common kinds we will see in this course are simple tubular and compound tubule-alveolar glands.V. Connective Tissuea. Many kinds of connective tissue: connective tissue proper, cartilage, bone and bloodb. All connective tissues have a large amount of material between their cells- extracellular matrixi. Opposite of epithelium which