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Tissues Chapter 5 Objectives: 1. List and describe the four major tissue types, and provide examples of where each occurs in the body. 2. Name the types of epithelium, and identify an organ in which each is found. 3. Distinguish different types of connective and muscular tissues. Tissue: • Def.: a group of similar cells that performs a specialized function • 4 major types of tissues: A. Epithelial Tissues • • Forms linings throughout the body Anchored to underlying connective tissue by a nonliving layer called basement membrane 1. Simple Squamous Epithelium - a single layer of thin, flattened cells – – – – Fit together tightly Broad, thin nuclei Substances pass through easily; easily damaged Found in lung air sacs, capillary walls, and membranes lining body cavities – ??? Epithelial Tissues (cont.) 2. Simple Cuboidal Epithelium – single layer of cube-shaped cells – Centrally located, spherical nuclei – Ovaries, kidney tubules, ducts of some glands – Adds in secretion and absorption Epithelial Tissues (cont.) 3. Simple Columnar Epithelium – longer than they are wide (elongated, like columns) – Thicker – Nuclei located near the basement membrane – Ciliated – found in female reproductive tubes – Nonciliated – lining of uterus, stomach, intestines Epithelial Tissues (cont.) 4. Pseudostratified Columnar Epithelium – appear to be stratified (layered), but are not – Why? Nuclei are found at different levels in the cells, instead of only near the basement membrane. – Many are ciliated. – Found lining respiratory passages Epithelial Tissues (cont.) 5. Stratified Squamous Epithelium – Many layers = thick (for protection) ??? – Outer layer of skin (“epidermis”) – Lining of mouth, throat, vagina, and anal canal 6. Stratified Cuboidal Epithelium – 2-3 layers of cuboidal cells lining a lumen – Lines large ducts of glands (mammary, sweat, salivary, pancreas) and of ovarian follicles and seminiferous tubules 7. Stratified Columnar Epithelium – Top layer elongated; base layer cube-shaped – Found in male urethra, vas deferens, and pharynx ??? Epithelial Tissues (cont.) 8. Transitional Epithelium – changes in response to tension – Found lining the bladder, ureters, and part of the urethra – Contracted – thicker; many layers ** – Relaxed – stretches and appears thinner • See Table 5.3, p. 99!! B. Connective Tissues • Made up of: – Cells, which are further apart than epithelial cells – Fibers – Matrix: intercellular material • Major cell types: 1. Fibroblasts – large, fixed, star-shaped cell that secretes fibers 2. Macrophages – wandering scavenger cells that defend against infection 3. Mast cells – large cells, located near blood vessels, that secrete heparin and histamine Fibroblast http://www.cimaging.net/applications/ examples/images/fibroblast3.jpg http://images.google.com/imgres?imgurl=http://education.vetmed.vt.edu/Curr iculum/VM8054/Labs/Lab5/IMAGES/MACROPHAGE%2520IN%2520SITU%2520c opy.JPG&imgrefurl=http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/ Lab5/Lab5.htm&h=542&w=720&sz=508&hl=en&start=53&tbnid=djc9Xtw5JvKw oM:&tbnh=105&tbnw=140&prev=/images%3Fq%3Dmacrophage%26start%3D3 6%26gbv%3D2%26ndsp%3D18%26hl%3Den%26sa%3DN Macrophage & Mast Cell http://upload.wikimedia.org/wikipedia/ commons/7/73/Macrophage_in_the_al veolus_Lung_-_TEM.jpg http://www.bu.edu/histology/ i/22602ooa.jpg http://www.healthsystem.virginia.edu/ internet/hematology/images/Mastcell-and-basophil-100x-websitearrow.jpg Connective Tissues (cont.) • Connective tissue fibers: 1. Strong, collagenous fiber (white fiber), made of the protein collagen; adds strength 2. Stretchy, elastic fiber (yellow fiber), made of the protein elastin; adds ____________. 3. Reticular fibers – thin collagenous fibers that form supportive networks in tissue Connective Tissues (cont.) 1. Loose Connective Tissue (“areolar tissue”) – Cells are some distance apart; separated by gellike matrix – Forms delicate, thin membranes – Binds skin to underlying organs, fills space between muscles Connective Tissues (cont.) 2. Adipose Tissue – fat – Large fat droplets in cells push nuclei close to the cell membranes. – Beneath the skin, between muscles, around kidneys, behind eyeballs, on heart, around joints Connective Tissues (cont.) 3. Dense Connective Tissue – closely packed, thick collagenous fibers + elastic fibers – Strong! – Binds organs together – Found in tendons, ligaments, deep skin layers Connective Tissues (cont.) 4. Cartilage – a rigid connective tissue – Chondrocyte: cartilage cell – Perichondrium: around cartilage; membrane surrounding cartilage; contains blood vessels to supply nutrients – Three types of cartilage, distinguished by intercellular (???) matrix: a) Hyaline cartilage b) Elastic cartilage c) Fibrocartilage Connective Tissue (cont.) a) Hyaline cartilage – Very fine collagenous fibers in matrix – White glass appearance – Ends of bones in joints, soft part of nose b) Elastic Cartilage – Dense network of elastic fibers = more flexible – Framework for external ears and parts of larynx c) Fibrocartilage – Very tough; many collagenous fibers – Forms intervertebral discs and pads between bones in knees and pelvic girdle Hyaline cartilage cells Elastic cartilage cells Fibrocartilage http://www.bartleby.com /107/Images/small/image 295.jpg http://cellbio.utmb.edu/microanatomy/bone /fcartilage.jpg Connective Tissue (cont.) 5. Bone – the most rigid connective tissue – Matrix made of mineral salts and collagen fibers – Osteocyte: bone cell 6. Blood • See Table 5.4, p.105!!! ??? C. Muscle Tissues 1. Skeletal muscle tissue (“voluntary”) – Long, threadlike cells – Striations: alternating light and dark crossmarkings – Each cell has many nuclei just beneath the cell membrane. Muscle Tissues (cont.) 2. Smooth muscle tissue (“involuntary”) – No striations – Cells are shorter than skeletal muscle, spindleshaped, and have one, centrally located nucleus. – Line walls of internal organs Muscle Tissues (cont.) 3. Cardiac muscle tissue – heart – Striated and joined end-to-end – Each cell has only one nucleus. ??? D. Nervous Tissue • Nervous tissue is – found in the brain, spinal cord, and nerves. – made up of: • Neurons: nerve cells • Neuroglial cells: helper cells – “glia” = glue – Support and bind components of nervous tissue to each other and to blood vessels • See Table 5.5, p.107!!!