1 / 42

TISSUES

TISSUES. STRUCTURAL ORGANIZATION. Life is characterized by hierarchical orders of organization Atoms Molecules Organelles Cells Tissues Organs Organ systems Organism (Population) (Community) (Ecosystem). STRUCTURAL ORGANIZATION.

mikko
Download Presentation

TISSUES

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. TISSUES

  2. STRUCTURAL ORGANIZATION • Life is characterized by hierarchical orders of organization • Atoms • Molecules • Organelles • Cells • Tissues • Organs • Organ systems • Organism • (Population) • (Community) • (Ecosystem)

  3. STRUCTURAL ORGANIZATION • The cell is the lowest level of organization that can live independently as an organism Amoeba Paramecium

  4. STRUCTURAL ORGANIZATION • In multicellular organisms, specialized cells are grouped into tissues • A tissue is a group of cells similar in structure and performing a common function • Organs are comprised of combinations of various tissues • Organ systems include multiple organs working together

  5. INTERCELLULAR JUNCTIONS • Neighboring cells within a multicellular organism often adhere, interact, and communicate through intracellular junctions • Tight junctions • Desmosomes • Gap junctions

  6. INTERCELLULAR JUNCTIONS

  7. TISSUE TYPES Four major tissue types • Epithelial tissue • Connective tissue • Muscle tissue • Nervous tissue

  8. EPITHELIAL TISSUE • Sheets of cells covering body surfaces or lining body cavities • Form boundaries between different environments • e.g., Epidermis of skin separates inside and outside of body • e.g., Epithelium lining urinary bladder separates underlying cells from urine

  9. EPITHELIAL TISSUE • Many diverse functions • Protection • Absorption • Filtration • Excretion • Secretion • Sensory reception

  10. CLASSIFICATION OF EPITHELIA Cell layers • Simple epithelia • Single cell layer • Facilitates absorption and filtration • Stratified epithelia • Two or more cell layers • Common in high-abrasion areas • e.g., Skin surface, mouth

  11. GLANDULAR EPITHELIA • A gland consists of one or more cells that produce and secrete a product (secretion) • Secretion: verb and noun • Endocrine vs. exocrine • Unicellular vs. multicellular

  12. ENDOCRINE GLANDS • “Ductless glands” • (Ducts are eventually lost) • Produce hormones • Secreted directly into extracellular space via exocytosis • Many (but not all) are epithelial derivatives • More information in their own chapter

  13. EXOCRINE GLANDS • More numerous than endocrine glands • Secrete into body cavities or onto body surfaces • (i.e., Not into extracellular space) • Unicellular glands via exocytosis • Multicellular glands via ducts • Diverse • e.g., Mucous, sweat, oil, and salivary glands, etc.

  14. EXOCRINE GLANDS Multicellular Glands: Structural Classification • Simple • Compound • Tubular • Alveolar (acinar) • Tubuloalveolar

  15. CONNECTIVE TISSUE • Found everywhere in the body • Most widely distributed primary tissue • Four main classes • Connective tissue proper • Cartilage • Bone tissue • Blood

  16. CONNECTIVE TISSUE • Major functions • Binding and support • Protection • Insulation • Transportation • Which of these functions are accomplished by bone and cartilage? Fat? Blood?

  17. CONNECTIVE TISSUE Common Characteristics • Common origin • All connective tissues arise from mesenchyme (an embryonic tissue) • Degrees of vascularity • Avascular • poorly vascular • highly vascular • Extracellular matrix • Largely composed of non-living extracellular matrix

  18. CONNECTIVE TISSUE • Three main structural elements • Ground substance • Fibers • Cells • Ground substance + fibers = matrix

  19. TYPES OF CONNECTIVE TISSUE Connective Tissue Proper • Two subclasses • Loose connective tissue • Areolar • Adipose • Reticular • Dense connective tissue • Dense regular • Dense irregular • Elastic

  20. TYPES OF CONNECTIVE TISSUE Cartilage • Three varieties • Hyaline cartilage • Elastic cartilage • Fibrocartilage

  21. TYPES OF CONNECTIVE TISSUE Bone (Osseous Tissue) • Matrix similar to cartilage • More abundant collagen fibers • Inorganic calcium salts • Rocklike hardness • Ability to support & protect

  22. TYPES OF CONNECTIVE TISSUE Bone (Osseous Tissue) • Osteoblasts produce organic portion of matrix • Bone salts then deposited on & between fibers • Osteoblasts  osteocytes • Osteocytes reside in lacunae within the matrix • Vascular

  23. TYPES OF CONNECTIVE TISSUE Blood • Very atypical connective tissue • Does NOT connect things • Provides NO mechanical support • Why is it considered connective tissue? • Derived from mesenchyme

  24. TYPES OF CONNECTIVE TISSUE Blood • Various types of cells • Blood plasma is fluid matrix • Plasma proteins are “fibers” • Various functions • Transportation • Protection

  25. MEMBRANES • Continuous multiple sheets comprised of • Epithelium • Underlying layer of connective tissue • Three types of covering and lining membranes • Cutaneous • Mucous • Serous These membranes are multicellular structures, and are quite different from the plasma membrane of a cell

  26. CUTANEOUS MEMBRANES • a.k.a., “Skin” • Organ system • Consists of • Keratinized stratified squamous epithelium • “Epidermis” • Thick layer of dense irregular connective tissue • “Dermis” • Dry membrane

  27. MUCOUS MEMBRANES • a.k.a., “Mucosae” • Line body cavities open to exterior • e.g., digestive, respiratory, & urogenital tracts • “Wet” membranes • Bathed in secretions or urine • Often adapted for absorption and secretion • Many secrete mucus • Not all (urinary)

  28. SEROUS MEMBRANES • a.k.a., “Serosae” • Moist membranes found in closed ventral body cavities • Consist of • Simple squamous epithelium (mesothelium) • Thin layer of loose connective (areolar) tissue • Name based on location • Pleura of lungs • Pericardium of heart • Peritoneum of abdominopelvic cavity

  29. SEROUS MEMBRANES • Produce serous fluid • Blood filtrate + hyaluronic acid secreted by mesothelium • Lubricates facing surfaces of parietal and visceral layers

  30. NERVOUS TISSUE • Main component of the nervous system • Brain, spinal cord, and nerves • Regulates and controls body functions • Two main cell types • Neurons • Generate and conduct nerve impulses • Supporting cells • Non-conducting cells that support, insulate, and protect neurons

  31. MUSCLE TISSUE • Highly cellular • Well vascularized • Responsible for most types of body movement • Possess myofilaments • Actin and myosin • Three types • Skeletal muscle • Cardiac muscle • Smooth muscle

  32. SKELETAL MUSCLE • Skeletal muscle cells • a.k.a., “Muscle fibers” • Long, cylindrical cells • Multinucleate • Striated • Voluntary

  33. SKELETAL MUSCLE • Forms organs called skeletal muscles • Packaged by sheets of connective tissue • Attached to bones of skeleton • Contract to pull on bones or skin • Movement results

  34. CARDIAC MUSCLE • Found only in the wall of the heart • Contractions propel blood through blood vessels • Cardiac muscle cells • “Myocytes” • Striated • Uninucleate • Branching • Involuntary

  35. SMOOTH MUSCLE • Found mainly in walls of hollow organs • e.g., Intestines, esophagus, blood vessels, etc. • Contractions squeeze substances through these organs • No visible striations • Smooth muscle cells • Spindle shaped • Uninucleate • Involuntary

  36. BODY DEFENSES • Mechanical barriers are the body’s first line of defense against injury and infection • Skin and mucous membranes • Respiratory cilia • Acids secreted into stomach and from skin • Tissue injury breaches this first line of defense • Stimulates inflammatory and immune responses • Second and third lines of defense, respectively • Tissue is ultimately repaired

  37. TISSUE REPAIR • Injured cells release growth factors • Stimulate cells to divide and migrate • Two major tissue repair means: • Regeneration • Replacement of destroyed tissue with same type of tissue • Fibrosis • Replacement with fibrous connective tissue (scar tissue) • Type of repair dependent upon • Type of tissue damaged • Severity of injury

  38. TISSUE REPAIR Inflammation • Injured cells, macrophages, and mast cells release inflammatory chemicals • Dilation and increased permeability of capillaries • Plasma and leukocytes enter injured area • Plasma proteins form clot • Halts blood loss • Isolates injured area • Prevents spread of microbes • Forms scab

  39. TISSUE REPAIR Organization • Blood clot replaced by granulation tissue • Capillaries • Proliferating fibroblasts • Produce growth factors, collagen fibers • Pull margins of wound together • Macrophages • Digest clot • Granulation tissue ultimately becomes scar tissue

  40. TISSUE REPAIR Permanent Repair • Surface epithelium begins to regenerate • Grows under scab • Scab ultimately detaches • Epithelium fully regenerated • Fibrous material beneath epithelium matures and contracts • Scar tissue beneath epithelium • Scar may be visible or not

  41. TISSUE REPAIR • The regenerative capacity of different tissues varies widely • Some tissues regenerate extremely well • e.g., Epithelial, bone, areolar connective tissue, blood-forming tissue • Some tissues have a moderate regenerative capacity • e.g., Smooth muscle, dense regular connective tissue • Some tissues have a weak regenerative capacity • e.g., Skeletal muscle, cartilage • Some tissues have a virtually no functional regenerative capacity • e.g., Cardiac muscle, nervous tissue

  42. TISSUE REPAIR • In non-regenerative tissue and severe wounds, damaged tissue is replaced by fibrosis • Resulting scar tissue is strong, but lacks flexibility, elasticity, and function of normal tissue

More Related