Histology, Chapter 1 (pt. 1)

Tissues

the living fabric

• Groups of cells similar in structure that perform common or related function

-4 types (epithelial, connective, muscle, and nerve)

Epithelial tissue function

covers surfaces (serosa = outside lining and mucosa = inside lining)

• protection (skin), absorption (mucosa), filtration (kidney), diffusion (lungs), excretion (GI)

connective tissue function

supports and connects

muscle tissue function

moves

nerve tissue function

controls

Epithelial tissue (Epithelium) locations

line the cavities and cover the surfaces

• lines digestive tract organs, hollow organs (capillaries, kidney, lung)

• skin surface (epidermis) and organ surface (serosa)

• interface tissue that rests upon connective tissue

Epithelial tissue characteristics

polarity, abundant cell junctions, supported by connective tissue, avascular, can regenerate, cytokeratin

polarity of epithelial tissue

Epithelial cells have polarity

• Apical surface: microvilli or cilia (outside)

• Basal Surface: connective tissue (basement membrane)

Abundant cell junctions in epithelial tissue

Tight (TOP)

Adherens

Desmosome

Gap

Hemidesmosome (BOTTOM)

Tight junction

Prevents paracellular movement of solutes (controls permeability)

• not an anchor junction

• Composed of claudins and occludins

• Creates the BBB

Adherens junction

Microfilment (actin) and cadherins (between cells)

• metastasis loosens cahderins

• Anchor junction

Desmosomes

Intermediate filaments (cytokeratin) and cadherins

• strongest

• Keeps heart from breaking

• Autoantibody to desmogien: pemphigus vulgaris (bubbles on skin)

Gap junction

Channel proteins, connexons, permit chemical and electrical communication

• in heart

• Ions can pass through

• Not an anchor junction

Hemidesmosome

Intermediate filaments (cytokeratin) collagen fibers in basement membrane

• autoantibody: bullous pemphigoid (bubbles)

• Anchor junction