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Histology Biology 2121Chapter 4
IntroductionIntroduction
• Histology - the study of tissue
• Four Tissue Types – 1. Epithelial – 2. Connective Tissue– 3. Muscle Tissue – 4. Nervous Tissue
Epithelial Tissue
• In the body found as – 1. covering or lining– 2. glandular epithelium
• General Functions– 1. protection– 2. absorption– 3. filtration– 4. excretion– 5. secretion– 6. sensory reception
Characteristics Characteristics • 1. Epithelial tissue - apical (upper )surface and basal
surface (lower)– Basal lamina - beneath the basal surface
• Glycoprotein - adhesive • filter (selective for the upper epithelial tissue)
• 2. Tight fitting tissue– Tight junctions & desmosomes
• 3. Connective tissue base below the basal lamina - ‘reticular lamina’– collagen fibers
• 4. Basal and reticular lamina = ‘basement membrane’
Classification
(1)Simple Squamous(2)Simple cuboidal(3)Stratified squamous(4)Simple Columnar
Classification
Classification - Columnar
Classification-Stratified
Glandular Epithelium
Introduction to Connective Tissue • Major functions
are binding and support – Protection,
insulation, transportation
• 4 classes
• Subclasses
• Mesenchyme – Embryonic
Characteristics of Connective Tissue
• 1. Vascular – Exception - cartilage
• 2. Stem cell - mesenchyme embryonic tissue
• 3. ‘Noncellular’ extracellular matrix– Fewer cells compared to
epithelial tissue – Makes it stronger, resist
abrasion, etc.
What does Connective look like?
• Extracellular matrix – Made of ground substance (‘matrix’) and
fibers.
• 1. Ground Substance– Between cells and holds fibers – Interstitial fluid; cell adhesion
proteins and (fibronectin, laminin); proteoglycans •Cell adhesion proteins allow for cells to attach to matrix
Ground Substance and Matrix• Proteoglycans - protein core
to which ‘glycosaminoglycans (GAGs) are attached (4.7)
– Polysaccharides (- charge); chondroitin; keratin sulfate; hyaluronic acid
– Traps water and forms a gel-like substance
– Allows for nutrients and substances to diffuse between blood and cells.
Fibers • Types
– 1. Collagen• Thick, tough, fiberous; resist
stress– Tendons and ligaments
– 2. Elastic• Long and thinner; made of
elastin; stretch and recoil; helps collagen to return to original shape
– Found in skin, lungs and BVs
– 3. Reticular • Short, fine and collagen;
continuous with collagen fibers• Branch and surround small BVs;
support soft tissue of organs; found in basement membrane of epithelial tissues
Cells Cells • 1. Connective tissue proper – ‘fibroblasts’
– ‘fibrocyte’
• 2. Cartilage – ‘chondroblast’– ‘chrondrocyte’
• 3. Bone – ‘osteoblast’ – ‘osteocyte’
• 4. Blood – hematopoietic stem cells– Blood cells (does not make fluid and is
not located in its tissue
• 5. Additional Cells- leukocytes (mast and phagocytes); plasma cells; macrophages
CellsCells
Above: Tendon- What identify the cell.Middle: Tissue? Cell?Right: Tissue? Cell?
Areolar CT is a general example of what connective tissue looks like
Survey of Connective Tissue Proper (loose CT)Survey of Connective Tissue Proper (loose CT)
Dense CT – CT Proper
Cartilage Cartilage
1. Hyaline Cartilage: firm, glassy matrix in which chondrocytes lie in ‘lacunae’
2. Joints; ribs (costal cartilage)
Cartilage Types
Bone and Blood
Nervous Tissue
• Brain and spinal cord • Cell types
– 1. neurons– 2. supporting cells or ‘neuroglia’
Muscle Tissue • Cellular -
Vascular– myofilaments
(actin and myosin) for movement and contraction
• Three types– 1. Skeletal – 2. Smooth – 3. Cardiac
Membranes that cover and line surfaces Membranes that cover and line surfaces
Membranes
Inflammatory Response and Tissue Repair (online notes) Inflammatory Response and Tissue Repair (online notes)
• 1. Inflammation– Injury, release of inflammatory
chemicals by cells; vasodilation; entry of neutrophils and monocytes; clotting proteins in plasma; scab forms
• 2. Organization– First phase of tissue repair; scab
replaced by granulation tissue (capillaries and other tissue); fibroblast produce growth factors and collagen; becomes a scar tissue
• 3. Regeneration – Surface epithelium regenerates;
epithelium on top of scar tissue replaces the scab