Anatomy and Physiology Chapter 4

Groups of cells that are similar in structure, function, and embryonic origin bound together with intercellular material

• Similar cells group together into three layers:
• Ectoderm: forms both outer covering of body and the nervous tissue
• Endoderm: forms inner lining of digestice tube and associated structures
• Mesoderm: layer between ectoderm and endoderm - forms skeleton and muscles

• Protection
• Absorption
• Secretion/Excretion
• Filtration

• Surface epithelia - singe layer of cells
• Provides very little protection
• Types: simple squamous epith; simple cuboidal epith; simple columnar epith; pseudostratified columnar epith.

• Two or more protective layers
• Function to protect
• Types: stratified squamous epith; stratified cuboidal epith; stratified columnar epith; transitional epith.

• Binding organs
• Support
• Movement
• Physical protection
• Immune defense
• Energy storage
• Mineral storage
• Heat production
• Transport

• Spindle shaped cells that synthesize and maintain fibers
• (fibrocytes are resting fibroblasts)

• Phagocytes (engulf foreign material)
• Function as immune defense
• Develop from monocytes

Contain granules with histamine

Fat cells

• Groundsubstance - water, proteoglycans, glycosaminoglycan
• Fibers

• Most abundant fiber type
• Main protein: collagen

• Found in tissues that stretch
• Main protein: elastin

• Form delicate supporting framework (stroma) for highly cellular organs
• Main protein: reticulin

Mesenchyme and mucous connective tissue

Fibroconnective tissue, cartilage, bone, liquid

• Loose fibroconnective tissue
• Most widespread CT
• Unorganized fiber arrangement with many spaces in between
• Used to: attach skin to underlying tissue; loosely pack organs; support blood vessel lining, GI, respiratory and urinary tracts

• Adipocytes (fat cells) are main cells - accumulate fat as droplets
• Increased blood vessel supply = increased metabolic activity
• Found anywhere areolar CT is found

• Loose fibroconnective tissue
• Fine network of branching reticular fibers
• Stroma for organs - spaces filled with blood cells

• Collagen fibers tightly packed in a parallel bundle
• Fibroblasts are only cells located between fibers
• Strong tissue with few blood vessels
• Used in: tendons, ligaments; fibrous membranes (fascia and aponeurosis)

• Fibers condensed into irregular masses
• Random fiber arrangement = tension resistance from all directions
• Used in: dermis layer of skin; periosteum and perichondrium; fibrous capsule around many organs

• Dense connective tissue
• Elastic fiber count > collagen fiber count
• Allow tissue stretch and return to normal
• Used in: walls of arteries, trachea, bronchi, vocal cords

• Semi-rigid connective tissue
• Groundsubstance: chondroitin sulfate provides resilience
• Collagen fibers provide strength
• Chondroblasts: cells that produce matrix (few)
• Chondrocytes: mature cartilage cells surrounded by lacunae
• Avascular matrix: no blood supply, so poor healing
• Perichondrium: zone of condense dense irregular CT at cartilage periphery - contains blood vessels and nerves
• 3 types: hyaline, elastic, fibrocartilage

• Specialized connective tissue
• Matrix is mineralized (inorganic salt) = increased rigidity and strength
• Vascular matrix: contains blood supply (Haversian Canals)
• Lacunae are interconnected by canaluculi (canals)

• Specialized connective tissue
• Formed elements: red blood cells, white blood cells, platelets
• Extracellular matrix: plasma

• Specialized connective tissue
• Contractile properties: function to move skeleton and organs, produce heat, and maintain posture
• Voluntary/conscious control
• Long and cylindrical muscle fiber with striations
• Multinucleated

• Functions: form wall of heart - contractile units create "pumping action"
• Contain myofibrils - just like skeletal muscle
• Have intercalated discs: gap junctions and desmosomes
• Single central nucleus
• Involuntary control

• Functions: forms walls of hollow internal structures (GI tract, blood vessels, ducts)
• Visceral muscle: not striated, short spindle-shaped cell with tapered ends
• Single central nucleus
• Involuntary control

Neurons and glial cells

Groups of secretory cells surrounded by network of capillaries - enter into blood stream

• Retain connection with epithelium from which they originate
• Connection serves as a duct - exit out of body

• Exocytosis: vesicles form with the product you want to excrete inside of them
• Zero cell destruction
• Most common mode of secretion
• Examples: pancreas, salivary glands, sweat glands

• Apical cytoplasm is shed with secretory vesicle
• Lose entire apical portion of cell - some cell damage
• Examples: some sweat glands and mammary glands, axillary, anal

• Whole cell ruptures
• Secretion accumulation in cells -> cell ruptures and dies when secretion released
• Example: sebaceous glands of the skin

• Like zipper
• Encircle epithelial cells near apex
• Seal intercellular space - plasma membranes held tightly together

• Form adhesion belts - like velcro
• Belt around one cell connects to belt around another cell

• Like a snap closure
• "Spot welds" between cells

• Doesn't really attach two cells together
• Attaches cells to extracellular structures (like basement membrane)

• Communicating junctions
• Allow substances to pass from one cell to another
• Important in muscle tissue (intercalated discs)

• Moist, epithelial membranes
• Line cavities opening to the outside
• Secrete mucus
• Three layers: epithelium, lamina propria, muscularis mucosa

• Line ventral body cavities which don't open to exterior
• Layers: simple squamous epithelium, thin layer of areolar CT
• Mesothelium cells secrete serous fluid

• Skin
• Stratified squamous epithelium + areolar and dense irregular CT (dermis)

• Line joint cavities
• Not epithelial membrane (only one!)
• Produce synovial fluid