The Histological Organization of Organisms – Four Tissue Types:

• covers, lines organs
• cells in close contact with no intercellular matrix
• separates body and organ compartments
• classified according to location, shape, cell layer
• simple squamous: flat, single layer, lining cells, allow exchange of nutrients
• simple cuboidal: square, single layer, absorption/secretion of materials
• simple columnar: single layer, absorption/secretion of materials
• stratified squamous: multi layer, protective
• pseudostratified columnar (ciliated): single layer

• consists of cells, extracellular fibers, matrix
• fills spaces between other tissues
• provides support, strength, elasticity
• classified according to the cells, matrix composition, organization
• cells:
• fibroblasts: produce fibers, ground subst
• fat cells: storage of fat/energy
• macrophages: wbc, lymphocytes (defensive function)
• matrix fibers:
• collagen fibers: majority, form bundles, give tension/strength
• reticular fibers: form meshwork, give support
• elastic fibers: gives elasticity/stretchability
• ground substance:
• proteoglycan and glycosaminoglycan
• glycoprotein: connects things together
• organiziation:
• loose connective tissue: found beneath epithelial tissue
• dense connective tissue: regular and irregular
• specialized connective tissue:
• adipose tissue (loose connect. tissue), bone, cart., lymphatic tissue

• classified according to function
• skeletal: striated, multinucleated, voluntary
• cardiac: striated, mononucleated, involuntary, in heart
• smooth: non-striated, mononucleated (‘corkscrew’), spindle shaped, involuntary
• specialized for movement, contraction
• one cell = one muscle fiber

(4) Nervous Tissue – central nervous system (cns) = brain and spinal cord; peripheral nervous system (pns) = everything else