1. Chapter 3 Body Tissues

2. Epithelial (epithelium) Tissue –Epithet = laid on, covering –Lining, covering, glandular –Functions: protection, absorption, filtration, secretion –Characteristics Fit closely forming continuous sheets Apical surface – 1 free surface – exposed to body’s exterior/interior Lower surface rests on basement membrane – secreted by the cells Avascular – no blood supply of their own –Depend on diffusion Regenerate

3. –2 names – based on # of layers and cell shape –Simple epithelia – one layer Simple squamous (fish scale) –Allow rapid diffusion – air sacs, capillaries –Produce serous membranes (serosae) – line ventral body cavity Simple cuboidal (cube shaped) –Glands and their ducts – salivary, pancreas –Kidney tubule walls –Ovary surface

4. Simple columnar (columns) –Goblet cells – produce lubricating mucus –Line digestive tract –Mucus membranes (mucosae) – line body cavities that open to exterior Pseudostratified columnar –Different heights –Line respiratory tract –May have cilia

5. –Stratified epithelia – 2 or more cell layers Stratified squamous –Most common –Esophagus, mouth, outer skin (friction areas) –Free edge – squamous –Basement membrane – cuboidal or columnar

6. Stratified cuboidal & Stratified columnar –Rare –Ducts of large glands Transitional –Modified stratified squamous – allow much stretching –Urinary bladder, ureters, part of urethra

7. –Glandular epithelium Glands – 1 or more cells that make and secrete a particular product –Endocrine glands »Ductless glands »Secretions diffuse directly into blood vessels »Ex. thyroid, adrenals, pituitary –Exocrine glands »Have ducts »Secretions empty directly on epithelial surface »Ex. sweat, oil, liver, pancreas

8. Connective tissue –Most abundant –Protection, support, binding –Characteristics Variation in blood supply – lower supply = slower healing

9. Extracellular matrix – nonliving substance bound outside cell produced by connective tissue –2 main elements 1.Ground substance »Water, adhesion proteins, polysaccharides »Fluid, gel-like, rock hard »Adhesion proteins – glue – attaches connective tissue to matrix fibers »Absorbs large amounts of water – reservoir 2. Fibers »Collagen – white – high tensile strength »Elastic – yellow – stretch/recoil »Reticular – internal skeleton of soft organs (spleen)

10. –Functions: forms soft packing tissue, bears weight, w/stand stretching/abrasions –Ex. Fat tissue – many cells – soft matrix –Ex. Bone/cartilage – few cells – hard matrix –Types – based on differences in fiber type and fiber # –Bone – osseous tissue Bone cells in cavities (lacunae) Surrounded by hard matrix w/ calcium salts and lots of collagen Support, protection

11. –Cartilage Hyaline cartilage –Most widespread –Abundant collagen, rubbery matrix –Ex. Surrounds larynx, attaches ribs to breastbone, covers ends of bones –Prenatal skeleton – replaced by bone by birth Fibrocartilage – cushioning disks of spinal cord Elastic cartilage – elasticity – ear

12. –Dense connective tissue (dense fibrous tissue) Collagen fibers Tendons – attach muscles to bone Ligaments – attach bone to bone Dermis – lower layer of skin

13. –Loose connective tissue More cells and fewer fibers Areolar tissue –Most widely distributed connective tissue –Cushions/protects body organs –Universal packing tissue –Glues internal organs together –Lamina propria – under all mucous membranes –Water/salt reservoir –Edema – swelling caused by collecting excess fluid –Phagocytes

14. Adipose tissue (fat) –Signet ring cells – contain large oil droplet that pushes nucleus to side –Subcutaneous tissue under skin »Insulates/prot ects –Fat deposits – hips, breasts

15. Reticular connective tissue –Forms stroma (bed) in lymph nodes, spleen, bone marrow

16. –Blood (vascular tissue) Blood cells surrounded by nonliving, fluid matrix (plasma) Fibers are only seen during clotting

17. Muscle tissue –Contract and shorten –Skeletal muscle Attached to skeleton Voluntary control Pulls on bone or skin – movement Multinucleate Striations Cells aka muscle fibers because their elongated

18. –Cardiac muscle Only in heart Involuntary control Uninucleate Striations Intercalated disks – where branching cells fit together – contain gap junctions

19. –Smooth muscle (visceral muscle) No striations Spindle shaped Found in walls of hollow organs – stomach, blood vessels Contraction – cavity smaller Relaxation – cavity larger Ex. Peristalsis – small intestines

20. Nerve tissue –Neurons – nerve cells –2 characteristics: irritability and conductivity –Cytoplasm drawn into long processes

21. Tissue Repair –Inflammation – nonspecific – attempts to prevent further injury –Immune responses – attacks specific invaders –Repair (healing) Regeneration – replacement of cells Fibrosis – repair by fibrous connective tissue – scar tissue –Type of repair determined by Type of tissue damaged Severity of damage

22. –Process Capillaries become permeable –Allow clotting to occur –Stop blood loss, holds wound edges, walls of injured area Granulation tissue forms –Composed largely of new capillaries –Contain phagocytes – dispose of clot and scar tissue Surface epithelium regenerates –Grows under scab –Scar may be visible – depends on severity of wound –Epithelial and connective tissues regenerate well. –Muscle and nervous may not regenerate at all.

23. Tissue Development –Neoplasm – loss of control over cell division May be benign or malignant –Hyperplasia – cells multiply due to an irritant or condition Ex. Breast enlargement due to pregnancy –Atrophy – decrease in size – not used or loses nerve supply