Human Anatomy Chapter 4 Flashcards
Atoms
Make up moleculess
Molecules
Make up cells
Cells
Make up tissues
Tissues
Make up organs
Organs
Make up organ systems
Organ systems
Make up organisms
Epithelial tissue
Cellularity, cells are bound close togther, no intercellular space
Polarity
Have an exposed apical surface, attached basal surface, is the term that is in reference to this structural and functional difference
Epithelioid cells
Epithelial cells without a free surface
Attachment
Basal layer is attached to the basal lamina
Avascularity
Do not contain blood vessels (do not bleed)
Functions of Epithelial tissue
Provides physical protection, from abrasion, dehydration, and destruction, controls permeability, provides sensation (neuroepithelia), produces secretions special gland cells (unicellular glands, glandular epithelia)
Microvilli
Increases surface area for absorption of material, found on apical surface of cells of the urinary and digestive tracts
Stereocilia
Long microvilli, commonly found in the inner ear and male reproductive tract
Ciliated epithelium
Moves substances over the apical surface, found lining the respiratory tract
Intercellular Connections
Extensive connection between the cells, holds the cells together, prevents the passage of chemicals and pathogens, cells junctions, CAMs, and intercellular cement give the epithelium strength and stability
Attachment to the basal lamina
The cell membrane attaches to the basement membrane, consists of typically two layers, basal lamina (plasma membrane), reticular lamina (connective tissue), reticular lamina in turn attaches to underlying connective tissue
Epithelial maintenance and renewal
Must be replaces frequently, due to exposure to: disruptive enzyme, toxic chemicals pathogens, mechanical abrasion, replaced through time via continual division of stem cells near the basal lamina
Simple epithelium
Epithelium has only one layer of cells, nuclei are approximately at the same level within each cell, found in protected areas such as the internal compartments of the body
Stratified epithelium
Epithelium has two or more layers of cells, found in areas where there are mechanical or chemical stresses
Squamous epithelium
Cells are relatively flat in appearance
Cuboidal epithelium
Cells are shaped like cubes
Columnar epithelium
Cells are longer than they are wide- shaped like columns
Simple squamous epithelium
Consists of very delicate cells, location:lining body cavities (mesothelium), lining the heart and thee blood vessels (Endothelium), function: reduces friction, absorbs and secretes material