Cell Junctions & Inflammation PDF
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This document covers the concept of cell junctions, explaining their types (gap, tight, and desmosomes), their roles in cell communication, and how they affect epithelial tissue. Additionally, it describes the inflammatory response to injuries in the body, including its triggers and stages. This information is relevant in the field of biology.
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Cell Junctions A characteristic of epithelia is cellularity (cell junction) cellularity is a characteristic of epithelial tissue, which is made up of cells that are tightly bound together with little to no space between them Intercellular connections –Cell junctions! ▪Form bonds with other cells...
Cell Junctions A characteristic of epithelia is cellularity (cell junction) cellularity is a characteristic of epithelial tissue, which is made up of cells that are tightly bound together with little to no space between them Intercellular connections –Cell junctions! ▪Form bonds with other cells or extracellular material 1.Gap junctions- allow rapid communication, held together by connexons, allow small molecules and ions to pass, coordinate contractions in heart muscle 2.Tight junctions- between two plasma membranes,adhesions belt attaches to terminal web, prevent passage of water and solutes keep enzymes, wastes, and acids in the lumen of the digestive tract 3.Desmosomes → next slide! Intercellular connections CONTINUED 3.Desmosomes- CAMs and proteoglycans link opposing plasma membranes Spot desmosomes- tie cells together, allow bending and twisting, Hemidesmosomes- attach cells to the basement membrane Inflammation 4.11 Tissue Injuries and Repair (1 of 4) Learning Outcomes: Describe how injuries affect the tissues of the body. Tissues respond to injury in two stages 1.Inflammation (inflammatory response) 2.Regeneration: to restore normal function Inflammatory response –Can be triggered by: ▪Trauma (physical injury) ▪Infection (the presence of pathogens) –Damaged cells release prostaglandins, proteins, and potassium ions –Damaged connective tissue activates mast cells Process of inflammation –Lysosomes release enzymes that destroy the injured cells and attack surrounding tissues –Tissue destruction is called: necrosis ▪Begins several hours after injury Necrotic tissues and cellular debris (pus) accumulate in the wound –Abscess is pus trapped in an enclosed area The ability to regenerate varies among tissues –Epithelia, connective tissues (except cartilage), and smooth muscle regenerate well –Skeletal muscle, cardiac muscle, and nervous tissues regenerate poorly, if at all –Damaged cardiac muscle cells are replaced by fibrous tissue through fibrosis
