BSCI201: Exam 2 Study GuideTissues- 4 types: Epithelial, Nervous, Muscle, Connective- Epithelial Tissueo Characteristics: Polarity Avascular Supported by a basement membrane Connective tissue underlies/supports providing nutrients Highly Regenerative Innervatedo 2 Main Classes: Membranous v. Glandularo Membranous covering and lining epithelia Simple = Single Layer, Stratified = multiple layers Identify by Shape of Apical cell - Squamous flat cell, flat nucleus- Cuboidal round, plump cell; round, centrally located nucleus- Columnar elongated cell; nucleus towards base of cell Simple Squamous – single layer made of squamous cells- Location: o Kidneys (filtration membrane) Function: Filtrationo Lungs Function: Diffusion of Gaseso Lines Structures in the Circulatory system (cardiovascular and lymphatic system) Specifically called the ENDOTHELIUM Function: Provides a slick, frictionless surface for the flow of blood and lympho In serous membrane= MESOTHELIUM Function: Act as a lubricant to reduce friction as structures move in the ventral body cavity Simple Cuboidal – single layer of cube-like cells with large spherical central nuclei- Location:o Kidneys Proximal Convoluted Tibule (PCT) and Distal Convoluted Tubule (DCT Function: Re-absorptiono Outer membrane on the surface of the ovaries = Germinal Epithelial Function: Re-absorption Simple Columnar – single layer of column shaped cells with an elongated nucleus towards - Ciliatedo Respiratory Tract cilia propels mucuso Female Reproductive Tract propels ova (eggs) or zygote- Non-ciliated secretion of enzyme required for chemical digestion of nutrients Pseudostratefied Columnar single layer of columnar calls of different heights with nuclei of varying heights BUT each cell is touching the basal membrane- Non-Ciliatedo Sperm Ducts phagocytize sperm that are not ejected through the urethral orifice- Ciliated Referred to as respiratory epithelialo Lines most of the structures in the RESPIRATORY TRACTo Endowed with goblet cells that secrete mucin Stratified Squamous Epithelium several layers of epithelial cells with the cell on the apical surface being flattened with disc shaped centrally placed nuclei- Keratinized: Cells on apical surface are dead impregnated with tough fibrous protein called keratin very abrasive resistanto Epidermis of skin protects against wear and tear; physical barrier against pathogens- Non-keratonized: Cells are alive, forms the superior part of the mucusmembrane which lines the tracts of the body opening to the exterioro Gastrointestinal Tract entry: oral cvity; exit: anal cavity Stratified Cuboidal Epithelial Tissue and Stratefied Columnar Epithelium- Main function: stratification confers protectiono Protects internal surface of ducts and therefore, involved in secretion- Rare in human body- Location: ducts of multi-cellular exocrine glands (sweat glands and salivary glands) Transitional Epithelium- Urinary Tracto Undergoes a transition from 6 layers with cuboidal apical cells to 3 layers with flatten squamous-like cells as these structures fill with urineo Glandular: epithelial cells form the secretory portion of the duct system of multicelular exocrine glands Endocrine: secretes their products directly into extracellular fluid Exocrine: secretes product onto body’s surface- 2 types: Unicellular and Multicellularo Uncellular – goblet cells are scattered within membranous epithelial that secrete mucino Multicellular Structural Classification- Duct System simple glands: unbranched duct; compound glands: branched ducts- Shape of secretory portion: alveolar v. tubular Functional Classification = mode of secretion- Apocrine: apex of sexretory cell pinches off to release accumulated product (no ex. in human body)- Merocrine: secretory cell undergois exocytosis to release product- Holocrine: secretory cells ruptures to release accumulated product (sebaceous glands)Connective Tissue- Mesenchyme gives rise to 4 types of cells that secrete connective tissue- Consistency of Matrix/ Ground Substanceo Fibroblasts gel-likeo Chondroblasts semi-solido Osteoblasts solido Hemoepoeitc Stem Cells fluid- Living portion = cells derived from mesenchyme that secrete connective tissue- Non-living Portion = extracellular matrix composed of ground substance and fiberso 3 types of Fibers Collagen, Elastic, Reticularo Ground Substance consists of intestinal fluid, adhesions molecules, and proteoglycans composed of glycosaminoglycons (GAGs) More GAGs in ground substance the more solid the matrix- 4 Classes of Connective Tissueo Connective Tissue Proper Living portion secreted by fibroblasts Consistency of ground substance is gel like 2 sub-classes- Looseo Areolar supports structures in the body Referred to as packing material of the body Highly Vascularized Lamina Propria underlies epithelial tissue in the mucus membrane Makes up the papillary layer of the dermis Function:- Supports other tissues by providing nutrients- By virtue of the presence of the immune cells (microphages, blood cells), its involved in the immune response- Edema (excess intestinal fluid) is held back by areolar connective tissueo Adipose also known as adipocytes Stores triglycerides Surrounds and supports all structures in the body Function- Cushioning- Holds structures in correct anatomical position- Provides Storage form of concentrated energyo 1 g of glucose = 4 kcalo 1 g of protein = 4 kcalo 1 g of fat = 9 kcalo Reticular found in lymphoid organs (spleen, thymus, lymphoids) forming a network called the stroma Lymphoid cells rside and proliferate in stroma to provide immunity By virtue of association, involved in fighting off infection- Dense high levels of fibers; also referred to as fibrous connective tissueo Dense Regular bundles of collagen fibers arranged in one direction Can withstand stress applied in only one direction Forms tendons, ligaments, and aponeuroses (sheet liketendons that connect muscles to muscles over skeletal structures) Poorly vascularized not taking enough nutrients therefore, takes a long time to repair tendonso Dense Irregular bundles of collagen fibers facing in all directions Can withstand stress applied from different directions Highly vascularized and provide nutrients to
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