Lab Activity 4Classification of TissuesMartini Chapter 4Portland Community CollegeBI 2312Tissues• Groups of cells similar in structure and function• Each tissue is then further subdivided into categories.• All organs are made of a combination of different tissues.• The four types of tissues• Epithelial• Connective• Muscle• Nerve3Epithelial TissueDistinguishing Characteristics1. Cellularity: Composed almost entirely of cells2. Polarity: apical and basal surfaces (top and a bottom)3. Attachment: Supported by connective tissue (basement membrane)4. Avascular: Contains no blood vessels: obtains nutrients by diffusion 5. Regeneration: Rapidly replaces lost cells by cell division4Classification of Epithelia1. First name:• Simple: one layer• Stratified: more than one layer2. Second name:• Based on the shape of the top layer of cells• Squamous (flat)• Cuboidal (square)• Columnar (rectangle)3. Two additional categories• Transitional• Pseudostratified5Classification of Epithelia6Classification of Epithelia• Squamous• Cuboidal• Columnar7Simple Squamous Epithelium• Single layer of flattened cells with disc-shaped nuclei and sparse cytoplasm8Simple Squamous Epithelium• Top View910Simple Squamous Epithelium11Simple Squamous Epithelium• Functions:1. Diffusion• Alveoli in the respiratory system allows for exchange of O2and CO22. Filtration• Capillaries allow fluid and other substances out and holds blood cells and proteins in3. Lubrication• Secretes lubricating substances in serosae12Simple Cuboidal Epithelium• Single layer of cube like cells with large, spherical central nuclei1314Simple Cuboidal Epithelium15Simple Cuboidal Epithelium• Functions:1. Secretion• Glands such as the thyroid are composed of simple cuboidal epithelium and secrete hormones ect…2. Absorption• In the kidney, the proximal convoluted tubule is composed of simple cuboidal epithelium and reabsorbs water and other nutrients from the filtered fluid16Simple Columnar Epithelium• Single layer of tall cells with oval nuclei toward the basal surface• Goblet cells are often found in this layer17Simple Columnar Epithelium18Simple Columnar Epithelium19Simple Columnar Epithelium• Functions1. Secretion• Example: In the stomach, these cells secrete digestive enzymes2. Absorption• Example: In the intestine, these cells absorb nutrients20Pseudostratified Columnar Epithelium• Single layer of cells with different heights; some do not reach the free surface• Nuclei are seen at different levels• May be ciliated (PCCE) or non-ciliated21Pseudostratified Columnar Epithelium22Pseudostratified Columnar Ciliated Epithelium (PCCE)23Pseudostratified Columnar Ciliated Epithelium (PCCE)• Functions1. Protection• Example: Lines the upper respiratory tract. The cilia sweep debris toward the throat2. Secretion• Example: May contain goblet cells (unicellular glands) that secrete mucus24Stratified Squamous Epithelium• Composed of several layers of cells• Top layer flat• Bottom layers any shape• Function in protection of underlying areas subjected to abrasion25Stratified Squamous Epithelium•Non-keratinized•Composed of several layers of cells•Top layer flat•Bottom layers any shape26Stratified Squamous EpitheliumNon-Keratinized27Stratified Squamous EpitheliumNon-Keratinized• Functions1. Physical protection against abrasion and pathogens• Non-Keratinized is associated with “moist” areas• Mouth• Throat• Esophagus• Anus• Vagina28Stratified Squamous EpitheliumKeratinizedLooks “flakey” on the top29Stratified Squamous EpitheliumKeratinized30Stratified Squamous EpitheliumKeratinized• Functions1. Physical Protection• Found only in the epidermis of the skin• Keratin is a protein that helps strengthen the cells against abrasion31Transitional Epithelium• Several cell layers, basal cells are cuboidal• Apical cells are dome shaped when not stretched• Apical cells are flat when stretched• Only found in Urinary System• Functions:1. Allows expansion and recoil after stretching32Transitional EpitheliumDistended bladder Empty bladder33Stratified Cuboidal and Columnar• Typically two cell layers thick• Rare• Functions:1. Secretion• Found in some sweat and mammary glands34Stratified Cuboidal Epithelium35Stratified Cuboidal Epithelium36Stratified Columnar Epithelium• Limited distribution in the body• To tell the difference between this and pseudostratified columnar, look at the nucleus.• The nuclei are lined up in a straight row• Function1. Protection• Found in the pharynx, male urethra, lining some glandular ducts, and anus37Stratified Columnar Epithelium38Stratified Columnar Epithelium39Connective Tissue• 4 Types1. Connective Tissue Proper2. Bone3. Blood4. Cartilage40Connective Tissue Features1. Specialized cells2. Matrix: Nonliving material between the cells that makes up most of the volume (ground substance + fibers)• Extracellular fibers• Ground substance: Composed chiefly of interstitial fluid, cell adhesion proteins, and proteoglycans• Specific composition varies between tissues (Blood=fluid, Cartilage=gel like, Bone=Solid)41Connective Tissue Fibers• Collagen Fibers: Fibrous protein molecules • Extremely tough • High tensile strength• Strongest type of fibers in connective tissue.42Connective Tissue Fibers• Elastic Fibers: Form branching networks • Elastin: a rubber like protein that allow it to act like a rubber band and snap back to its original shape after it is stretched• Reticular Fibers: Forming delicate networks• Fine collagenous fibers (with a different chemical structure) branch extensively• Surround small blood vessels and support soft tissue organs43Cells of Connective Tissue Proper1. Fibroblasts: Secrete the matrix2. Macrophages: Scavenger cells that engulf pathogens or damaged cells3. Adipocytes: Fat cells4. Mesenchymal Cells: Stem cells5. Mast cells: Stimulate local inflammation: contain histamine and heparin6. Lymphocytes/microphages: WBC involved in immunity44Areolar Connective Tissue (Loose)• Gel like matrix• Contains all 3 fiber types• Functions:1. Wraps and cushions organs2. Holds and conveys tissue fluid• Locations:1. Under epithelial tissues2. Packages organs3. Surrounds capillaries45Areolar Connective Tissue (Loose)FibroblastCollagen fiberMacrophageElastic fiber46Adipose Tissue (Loose)• Function:1. Storage of lipid molecules2. Insulation47Reticular Connective