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Cells and Tissues

Explore the characteristics, functions, and classifications of epithelial tissues, including simple and stratified epithelia, as well as glandular epithelium. Learn about the ubiquitous presence and essential roles of connective tissues in the body.

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Cells and Tissues

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  1. Cells and Tissues

  2. Body Tissues • Tissues • Groups of cells with similar structure and function • Four primary types • Epithelial tissue (epithelium) • Connective tissue • Muscle tissue • Nervous tissue

  3. Epithelial Tissues • Locations • Body coverings • Body linings • Glandular tissue • Functions • Protection • Absorption • Filtration • Secretion

  4. Epithelium Characteristics • Cells fit closely together and often form sheets • The apical surface is the free surface of the tissue • The lower surface of the epithelium rests on a basement membrane • Avascular (no blood supply) • Regenerate easily (readily divide) if well nourished

  5. Epithelium Characteristics Figure 3.17a

  6. Classification of Epithelia • Number of cell layers • Simple—one layer • Stratified—more than one layer • Pseudostratified Columnar – appears to have several layers but only has 1 layer Figure 3.17a

  7. Classification of Epithelia • Shape of cells • Squamous • flattened • Cuboidal • cube-shaped • Columnar • column-like Figure 3.17b

  8. Simple Epithelia • Simple Squamous • Single layer of flat cells • Usually forms membranes • Basement membrane anchors epithelium to underlying connective tissue. • Location: Capillary walls, blood vessels, air sacs in lungs, inner surface of ear drum, lymph vessels • Function: filtration, diffusion, osmosis, protection

  9. Simple Epithelia Figure 3.18a

  10. Simple Epithelia • Simple Cuboidal • Single layer of cube-like cells • Closely packed • Basement Membrane with free surface • Location: Common in glands and their ducts, walls of kidney tubules, covers the ovaries • Function: protection, secretion, and absorption

  11. Simple Epithelia Figure 3.18b

  12. Simple Epithelia • Simple Columnar • Single layer of tall cells • Basement membrane • Location: Lines digestive tract (stomach and intestine wall), uterus • Function: Secretion (often includes mucus-producing goblet cells),absorbs nutrients from digested food, protection, moves eggs • Can be ciliated or nonciliated

  13. Simple Epithelia Figure 3.18c

  14. Simple Epithelia • Pseudostratified Columnar • Single layer, but some cells are shorter than others • Often looks like a double layer of cells • Commonly ciliated (Pseudostratified Ciliated Columnar Epithelium) • Basement membrane • Location: Respiratory tract (trachea, nasal cavity, bronchi, bronchioles, lungs) • Function: Secretion, Protection, Moves mucous • Goblet cells within tissue secrete mucous

  15. Simple Epithelia Figure 3.18d

  16. Stratified Epithelia • Stratified Squamous • 2 or more layers • Cells at the apical surface are flattened (in the deeper layers, they may be cuboidal or columnar) • Tightly packed • Basement membrane • Function: Found as a protective covering where friction is common, regeneration of cells, keratinization (in epidermis) • Locations: Epidermis, lines oral cavity, esophagus, vagina, anal canal

  17. Stratified Epithelia Figure 3.18e

  18. Stratified Epithelia • Stratified cuboidal • Two or more layers of cube shaped cells • Basement Membrane • Location: Lines larger ducts of mammary glands, sweat glands, salivary glands, and pancreas. • Function: protection, secretion, and absorption

  19. Stratified Epithelia • Stratified Columnar—surface cells are columnar, cells underneath vary in size and shape • Location: male urethra, ducted deferens, pharynx • Function: protection and secretion • Stratified cuboidal and columnar • Rare in human body • Found mainly in ducts of large glands

  20. Stratified Epithelia • Transitional epithelium • Shape of cells depends upon the amount of stretching • Function: Change in response to increased tension – expandable lining • Location: Lines organs of the urinary system

  21. Stratified Epithelia Figure 3.18f

  22. Glandular Epithelium • Glands • One or more cells responsible for secreting a particular product • Exocrine Glands – glands that secrete their products into ducts that open onto surfaces (skin, digestive tract) • Endocrine Glands- glands that secrete their products into tissue fluid or blood.

  23. Glandular Epithelium • Two major gland types • Endocrine gland • Ductless since secretions diffuse into blood vessels • All secretions are hormones • Exocrine gland • Secretions empty through ducts to the epithelial surface • Include sweat and oil glands

  24. Connective Tissue • Found everywhere in the body • Includes the most abundant and widely distributed tissues • Functions • Binds body tissues together • Supports the body • Provides protection

  25. Connective Tissue Characteristics • Variations in blood supply • Some tissue types are well vascularized • Some have a poor blood supply or are avascular • Extracellular matrix • Non-living material that surrounds living cells

  26. Extracellular Matrix • Two main elements • Ground substance—mostly water along with adhesion proteins and polysaccharide molecules • Fibers • Produced by the cells • Three types • Collagen (white) fibers • Elastic (yellow) fibers • Reticular fibers

  27. Connective Tissue Types • Bone (osseous tissue) • Composed of • Osteon, central canal, lamella, osteocytes, solid matrix of calcium salts, collagen fibers • Location: In spongy and compact bone (femur, humerus) • Function: Protection, support, framework, mineral storage

  28. Connective Tissue Types Figure 3.19a

  29. Connective Tissue Types • Hyaline cartilage • Most common type of cartilage, glassy appearance • Composed of: • Chondrocytes, collagen fibers, rubbery matrix • Locations: ends of bones, end of nose, ribs, larynx • Function: Support, framework, smooth surface, bone growth/development

  30. Connective Tissue Types Figure 3.19b

  31. Connective Tissue Types • Elastic cartilage • Location: Supports the external ear • Function: Provides elasticity, more flexible than hyaline • Fibrocartilage • Highly compressible, tough, collagenous fibers • Location: Forms cushion-like discs between vertebrae, knee, pelvic girdle • Function: Shock absorption

  32. Connective Tissue Types Figure 3.19c

  33. Connective Tissue Types • Dense Regular Connective Tissue (dense fibrous tissue) • Main matrix element is collagen fiber (tightly packed) • Fibroblasts are cells that make fibers • Locations: • Tendons—attach skeletal muscle to bone • Ligaments—attach bone to bone at joints • Dermis—lower layers of the skin • Function: strength, support, bind organs, connects bones to bone, and muscles to bones.

  34. Connective Tissue Types Figure 3.19d

  35. Connective Tissue Types • Loose connective tissue types • Loose Areolar Tissue • Most widely distributed connective tissue • Soft, loosely intertwined, pliable tissue like “cobwebs” • Contains all fiber types (elastic and collagen), in a gel-like matrix • Location: below epithelial tissues, between muscles, in wall of stomach and intestines, dermis, blood vessels • Function: flexibility, support, connects epithelium to muscle, “packing tissue”, can soak up excess fluid (edema)

  36. Connective Tissue Types Figure 3.19e

  37. Connective Tissue Types • Loose connective tissue types • Loose Adipose tissue • Matrix is an areolar tissue in which fat globules predominate • Adipocytes store fat (lipid deposits) in droplets in cytoplasm • Nucleus is pushed to the side, against plasma membrane • Location: Under skin, around joints, around organs, behind eye ball • Functions: Insulation, protection, support, energy storage

  38. Connective Tissue Types Figure 3.19f

  39. Connective Tissue Types • Loose connective tissue types • Reticular connective tissue – NOT ON TEST • Delicate network of interwoven fibers • Forms stroma (internal supporting network) of lymphoid organs • Lymph nodes • Spleen • Bone marrow

  40. Connective Tissue Types Figure 3.19g

  41. Connective Tissue Types • Blood Connective Tissue (vascular tissue) • Blood cells surrounded by fluid matrix called blood plasma • Formed Elements: Red blood cells, white blood cells, platelets • Fibers are visible during clotting • Location: In blood vessels (veins, arteries, capillaries), heart chambers • Function: Transport vehicle for materials (oxygen, nutrients, wastes, hormones), immunity

  42. Connective Tissue Types Figure 3.19h

  43. Muscle Tissue • Function is to produce movement • Three types • Skeletal muscle • Cardiac muscle • Smooth muscle

  44. Muscle Tissue Types • Skeletal muscle • Characteristics of skeletal muscle cells: • Striated • Multinucleate (more than one nucleus) • Long, cylindrical • Function: Voluntary movement of bones, produces heat, facial expression • Location: attached to bones of the skeleton (biceps, quadriceps)

  45. Muscle Tissue Types Figure 3.20a

  46. Muscle Tissue Types • Cardiac muscle • Characteristics of cardiac muscle cells • Cells are attached to other cardiac muscle cells at intercalated disks • Striated • One nucleus per cell • Branching cells • Location: Heart Wall • Function: Contraction of heart wall (pump blood), involuntary, produces heat

  47. Muscle Tissue Types Figure 3.20b

  48. Muscle Tissue Types • Smooth muscle • Characteristics of smooth muscle cells • No visible striations • One nucleus per cell • Spindle-shaped cells • Location: Wall of hollow organs (stomach, intestines, colon, bladder, uterus, blood vessels) • Function: Involuntary movement of organs (digestion), produce heat

  49. Muscle Tissue Types Figure 3.20c

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