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Chapter 4 Tissues 4 types of tissues 1. Epithelial 2. Connective 3. Muscular 4. Nerve Epithelial (exchange occurs through diffusion) Avascular (without blood) 1. Squamous-flat, tile-shaped, most delicate, stratified (layered) 2. Cuboidal- cube-shaped 3. Columnar-columns, ciliated, stratified, pseudostratified (nucleus is spread out) Functions: filters, protects absorbs, and secretes Connective-most abundant & widely distributed Vascular Tissue=blood flow Functions: Binds Insulates Supports Strengthens Muscular 3 types that contract or shorten to produce a movement 1. Skeletal 2. Cardiac 3. Smooth Skeletal Voluntary Forms flesh of body Muscles pull on bones Are long, cylindrical, and striated (striped) multinucleated Cardiac Only in heart Striated or striped Only one nucleus Involuntary Cells fit together by intercalated disks Smooth-also called visceral muscle No striations Single nucleus that is usually centered Cells are long, tapered with points at end Found in hollow organs Involuntary Contracts slower than other Nervous Conducts electrical impulses Function: conductivity and irritability Location: brain, spinal cord, and nerves (all over body) Nervous tissue Tissue Repair When tissue is injured it stimulates inflammatory and immune responses. Healing starts immediately Repair occurs in 2 ways 1.Regeneration- replacement of destroyed tissue by same kind of cell 2.Fibrosis- formation of scar tissue Which of these occur depends on… 1. Type of tissue damaged 2. Severity of clean cuts (incisions) heal more successfully than lacerations (tear How tissue repair works: a)Broken blood vessels bleed & soak area. Inflammation chemicals are released, WBC’s, fluid and proteins are able to enter. Proteins cause a clot. Surface dries & forms scab. b.) Granulation tissue forms-delicate, pink tissue made up of capillaries, phagocytes, connective tissue cells to bridge the gap. c.) Epithelium on top is repairing (mitosis). Makes way under scab and soon detaches Repair •Epithelial •Connective (bone) Poorly Repair Don’t repair •Cardiac •Skeletal •Nervous *Only replaced by scar tissue (strong, lacks flexibility) Tissue Growth All cells grow and divide until puberty. Skin and intestinal cells continue the process. Other cells only grow and replace when needed. Others never repair
