4 Epithelium Characteristics Avascular (no blood supply)Relies on circulatory system to obtain food and oxygenSurrounding connective tissues supply via diffusion from nearby capillariesRegenerate easily if well nourished (through normal cell division)Those on the exterior of the skin are exposed to friction and other hostile substances and are therefore lost
8 Figure 3.17b Classification and functions of epithelia. SquamousCuboidalColumnar(b) Classification based on cell shape
9 Figure 3.17c Classification and functions of epithelia. Number of layersOne layer: simple epithelial tissuesMore than one layer: stratified epithelial tissuesCell shapeSquamousDiffusion and filtration Secretion in serous membranesProtectionCuboidalSecretion and absorption; ciliated types propel mucus or reproductive cellsProtection; these tissue types are rare in humansColumnarSecretion and absorption; ciliated types propel mucus or reproductive cellsTransitionalProtection; stretching to accommodate distension of urinary structures(c) Function of epithelial tissue related to tissue typeRemember these general characteristics and you will be able to classify each type a lot easier !!
11 Nucleus of squamous epithelial cell Figure 3.18a Types of epithelia and their common locations in the body.Air sacs of lungsNucleus of squamous epithelial cellNuclei of squamous epithelial cellsBasement membranePhotomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (275×).(a) Diagram: Simple squamous
13 Nucleus of simple cuboidal epithelial cell Figure 3.18b Types of epithelia and their common locations in the body.Nucleus of simple cuboidal epithelial cellSimple cuboidal epithelial cellsBasement membraneBasement membraneConnective tissuePhotomicrograph: Simple cuboidal epithelium in kidney tubules (250×).(b) Diagram: Simple cuboidal
15 Nucleus of simple columnar epithelial cell Figure 3.18c Types of epithelia and their common locations in the body.Mucus of a goblet cellNucleus of simple columnar epithelial cellSimple columnar epithelial cellsBasement membraneBasement membranePhotomicrograph: Simple columnar epithelium of the small intestine (575×).(c) Diagram: Simple columnar
17 Pseudo- stratified epithelial layer Figure 3.18d Types of epithelia and their common locations in the body.CiliaPseudo- stratified epithelial layerPseudo- stratified epithelial layerBasement membraneBasement membraneConnective tissuePhotomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (560×).(d) Diagram: Pseudostratified (ciliated) columnar
19 Stratified squamous epithelium Stratified squamous epithelium Figure 3.18e Types of epithelia and their common locations in the body.NucleiStratified squamous epitheliumStratified squamous epitheliumBasement membraneBasement membranePhotomicrograph: Stratified squamous epithelium lining of the esophagus (140×).Connective tissue(e) Diagram: Stratified squamous
22 Transi- tional epithelium Figure 3.18f Types of epithelia and their common locations in the body.Basement membraneTransi- tional epitheliumTransitional epitheliumBasement membraneConnective tissuePhotomicrograph: Transitional epithelium lining of the bladder, relaxed state (270×); surface rounded cells flatten and elongate when the bladder fills with urine.(f) Diagram: Transitional
Your consent to our cookies if you continue to use this website.