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Blood

Blood. Fluid connective tissue Function: transport cells & dissolved matter Ground substance = plasma Formed elements = cells & cell fragments. 1-RBC 2-WBCs 4-Platelets. Blood. Erythrocytes (RBCs) – O2 & CO2 Leukocytes (WBCs) – immune functions Neutrophils Eosinophils, Basophils

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Blood

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  1. Blood • Fluid connective tissue • Function: transport cells & dissolved matter • Ground substance = plasma • Formed elements = cells & cell fragments

  2. 1-RBC 2-WBCs 4-Platelets

  3. Blood • Erythrocytes (RBCs) – O2 & CO2 • Leukocytes (WBCs) – immune functions • Neutrophils • Eosinophils, • Basophils • Lymphocytes • Monocytes • Platelets – cell fragments, clotting & vessel growth factor

  4. Nerve Tissue • Excitable tissue – has membrane potential • Voltage difference between outer & inner membrane • Results in rapid transition of signals to other cells • Located brain, spinal cord, nerves, ganglia

  5. Nerve Tissue • Neuron (nerve cell) • Soma (cell body) • Dendrites (input) • Axon (output) • Neuroglia or Glial cells (white matter)

  6. Muscle Tissue (Table 5.10) • Specialized contractile cells (spindle) • Exert physical force on other tissues • Important source of body heat (contraction) • 3 types of muscle: • Skeletal • Cardiac • Smooth

  7. Skeletal Muscle • Long cylindrical cells – muscle fibers • Striated (alternating light & dark bands) • Voluntary (conscious control over contraction)

  8. Cardiac Muscle • Only in the heart • Shorter cells – myocytes • Joined together at ends by intercalated discs • Striated & involuntary

  9. Smooth Muscle • Short fusiform cells • Non-striated with only one central nucleus • Involuntary contraction • Primary muscles of viscera

  10. Intercellular Junctions • Connections between cells • Means of Communication • Resists stress to tissue

  11. Tight Junctions • Encircles cell near Apex • Zipperlike with grooves and ridges • Prevents passage between cells

  12. Desmosomes • “Snap-like” • Doesn’t encircle cell • Located in epidermis, cardiac myo, & cervix

  13. Gap Junctions • Protein ring around water-filled pore • small solutes pass through cell to cell • Intercalated discs & smooth myo • Allows ions flow for electrical excitation

  14. Endocrine & Exocrine Glands • Exocrine glands secrete through duct • Sweat, mammary, tears • Endocrine glands secrete hormones directly into bloodstream • Pituitary, thyroid, adrenals • Some organs have both kinds • liver, gonads, pancreas

  15. Exocrine Gland Structure • Enclosed in fibrous capsule • Septa or trabeculae divide glands into lobes • Stroma is framework (CT) • Parenchyma are active cells

  16. Types of Exocrine Glands • Simple unbranched duct • Compound branched duct • Shape of gland: acinar - secretory cells form dilated sac tubuloacinar - both tube and sacs

  17. Types of Secretions • Serous glands • thin, watery secretions • sweat, milk, tears and digestive juices • Mucous glands • Mucin + water = mucus • Mixed glands contain both types • Some salivary glands • Cytogenic glands release whole cells • sperm & egg cells

  18. Methods of Exocrine Secretion • Merocrine (eccrine) Glands • Secretes via exocytosis • Tears, pancreas, gastric, sweat • Apocrine (also merocrine) • Holocrine • Entire cell disintegrates • Sebaceous glands of scalp

  19. Merocrine & Holocrine Secretion

  20. Mucous Membranes Lamina propria = areolar connective tissue

  21. Tissue Growth • Hyperplasia = growth by cell multiplication • Hypertrophy = growth by increasing size • muscle grow through exercise • Neoplasia = tumor growth (benign or malignant) abnormal, nonfunctional tissue

  22. Changes in Tissue Types • Differentiation • Development of unspecialized tissues into specialized mature types • mesenchyme becomes muscle • Metaplasia • Mature tissue change into another • Normal: simple cuboidal tissue before puberty changes to stratified squamous after puberty • Abnormal: smokers – pseudostratified columnar of bronchi into stratified squamous

  23. Stem Cells-undifferentiated cells • Embryonic stem cells • Totipotent (any cell type possible) • source = cells of very early embryo • Pluripotent (tissue types only possible) • source = cells of inner cell mass of embryo • Adult stem cells • Multipotent (several possible cell type – but not all) • Unipotent (only epidermal cells produced)

  24. Tissue Repair • Regeneration • replacement of damaged cells with functioning cells • skin injuries and liver regenerate • Fibrosis • replacement of damaged cells with scar tissue • Loss of function - healing muscle injuries, scarring of lung tissue in TB or healing of severe cuts and burns of the skin • Keloid - excessive fibrosis during healing (raised shiny scars)

  25. Clot & Scab forms on surface Macrophages start to clean up debris Antibodies, clotting factors and WBCs drawn wound

  26. New capillaries – Fibroblasts deposit collagen – May last 2 weeks Epithelials multiply beneath scab Epi-layer thickens Connective tissue scars (fibrosis) Phase may last 2 years

  27. Tissue Shrinkage and Death • Atrophy = loss of cell size or number • disuse atrophy from lack of use (leg in a cast) • Necrosis = pathological death of tissue • gangrene – tissue death from lack of blood • infarction - death of heart tissue from lack of blood • Apoptosis = programmed cell death • cells shrink and are phagocytized (no inflammation)

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