Biol 223 A&P 1 Chapter 4 Fa17.pptx - Biol 223 A&P 1 Chapter 4 Tissues 1 Tissues Tissues A group of like cells attached together by cellular

Biol 223 A&P 1 Chapter 4 Fa17.pptx - Biol 223 A&P 1 Chapter...

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Biol 223 A&P 1 Chapter 4: Tissues 1
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Tissues Tissues A group of like cells attached together by cellular junctions Have with discrete structural and functional properties Tissues in combination form organs, such as the heart or liver In the human body, there are 4 types of tissues Epithelial tissue Connective tissue Muscular tissue Nervous tissue Most cells within a tissue are and remain anchored to other cells or structures A few cells, such as phagocytes, move freely throughout the body, looking for foreign cells Migration of cells is much more common during growth and development 2
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4 types of tissue Epithelial tissue Covers body surfaces and lines hollow organs, body cavities and ducts Forms glands Allows the body to interact with both the internal and external environments Connective tissue Protects and supports the body and its organs Various types of connective tissue bind organs together Stores energy reserves as fat Provides immunity to disease causing organisms (infectious disease) 3
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4 types of tissue Muscular tissue Composed of cells specialized for contraction and generation of force Critical for movement of the organism Muscle contractions produce heat, providing warmth for the organism Nervous tissue Detect changes in a variety of conditions both inside and outside of the body Respond to changes by generating electrical signals called nerve action potentials (nerve impulses) Nerve impulses activate muscular contractions and glandular secretions 4
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Cellular junctions Most cells in a tissue are anchored together This provides form and organization to the tissue Cell junctions are the contact points between the plasma membranes of cells in tissues There are 5 predominant types of cell junctions Tight junctions Adherens junctions Desmosomes Hemidesmosomes Gap junctions 5
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Tight junctions Tight junctions consist of web- like strands of transmembrane proteins that fuse the plasma membranes of adjacent cells together This effectively seals off the space between the adjacent cells Commonly found in the cells that line the stomach, intestine and urinary bladder These junctions prevent the passage of substances (say stomach contents) between cells This prevents the leakage in to the blood and surrounding tissue 6
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Adherens junctions Cell junctions that resist separation of cells during contractile activities or motions Contain plaque, a dense layer of protein inside of the plasma membrane The plaque is bound to both the cytoskeleton, via microtubules, and membrane proteins The plaque from adjacent cells are linked together by transmembrane glycoproteins called cadherins The cadherins from adjacent plaques bind together in the intercellular space In epithelial cells, adherens junctions often form adherens belts Extensive zones of adherens junctions that encircle cells, just like a belt encircles your waist 7
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