Biology Chapter on Tissues

Study Notes

Tissues are groups of similar cells that work together to perform specific functions.

Covers surfaces, lines internal passages, and forms glands.
Tightly packed cells create barriers with distinct apical and basal surfaces.
Apical surface features include goblet cells (secretion), cilia (movement), and microvilli (absorption).
Keratinized cells provide abrasion resistance; basal surface is anchored by a collagen and glycoprotein basement membrane.
Epithelial tissues are avascular; they derive nutrients from underlying connective tissue.
Regeneration is rapid, and nerve endings are abundant.

Based on shape:
- Squamous (thin and flat)
- Cuboidal (square-shaped)
- Columnar (tall and slender)
Based on layers:
- Simple epithelium (single layer)
- Stratified epithelium (multiple layers)

Simple Squamous Epithelium: Facilitates absorption and diffusion (e.g., lungs, kidneys).
Simple Cuboidal Epithelium: Involved in secretion and absorption (e.g., glands).
Simple Columnar Epithelium: Absorption and secretion in stomach and intestines.
Stratified Squamous Epithelium: Protects against abrasion (e.g., skin, oral cavity).
Transitional Epithelium: Allows stretching and recoiling without damage (e.g., urinary bladder).
Pseudostratified Columnar Epithelium: Appears stratified but is a single layer; often found in the respiratory tract.

Endocrine Glands: Secrete hormones into interstitial fluid (no ducts).
Exocrine Glands: Release secretions onto epithelial surfaces via ducts; can employ:
- Merocrine secretion (vesicular)
- Apocrine secretion (shedding cytoplasm)
- Holocrine secretion (cell death and replacement).

Connect epithelium to the body and provide support, structure, and energy storage.
Characteristics include scattered cells in a matrix composed of ground substance and fibers (collagen, elastic, and reticular).
Vascularity varies; cartilage is typically avascular.

Connective Tissue Proper: Connects and protects organs; includes:
- Loose connective tissues (areolar, adipose, reticular) for support.
- Dense connective tissues (regular and irregular) for strength.
Fluid Connective Tissues: Blood and lymph for transportation and immunity.
Supportive Connective Tissues: Cartilage for flexibility and cushioning; bone for structural support.

Three types:
- Skeletal Muscle: Striated, voluntary, multinucleated, and does not regenerate well.
- Cardiac Muscle: Striated, involuntary, single nucleus, connected by intercalated discs, limited regeneration.
- Smooth Muscle: Non-striated, involuntary, single nucleus, capable of regeneration.

Physical barriers composed of epithelial tissue and supported by connective tissue.
Types include:
- Mucous Membranes: Line passageways open to the exterior; contain goblet cells.
- Serous Membranes: Line closed body cavities; secrete lubricating fluid.
- Cutaneous Membrane: Skin; keratinized stratified squamous epithelium.
- Synovial Membranes: Line joints and produce synovial fluid for lubrication.

Inflammation Phase: Characterized by swelling, redness, heat, and pain; involves histamine release and increased blood flow.
Granulation Phase: Formation of new blood vessels and connective tissue; fibroblasts secrete collagen.
Maturation Phase: Tissue regeneration restores normal function; fibrosis occurs when scar tissue forms instead.