Epithelial+Classification

=Classifying Epithelial Tissue=

Classifying by layers
**Simple ** is one layer It is good for absorption and filtration **Stratified ** is more than 1 layer It is good for protection **Pseudostratified ** Pseudo means false False stratified Looks multi-layered but it’s not All cells connect to the basement membrane but the cell height varies **Classifying Epithelial Tissue by Shapes ** **Squamous ** Flat and has few organelles so it has a low activity rate Cuboidal is as tall as it is wide, has a moderate activity level because of a moderate number of organelles Columnar are taller than they are wide and are a busy cell with lots of organelles <span style="color: black; font-family: 'Arial','sans-serif';">With 3 shapes and 3 layers we can mix and match to get a variety of tissue structures and ultimately functions **<span style="font-family: 'Arial','sans-serif';">Simple squamous <span style="color: #548dd4; font-family: 'arial','sans-serif';">(Figure 4.3a, page 120) ** <span style="color: black; font-family: 'Arial','sans-serif';">Single layer of flattened cells with disc-shaped nuclei and sparse cytoplasm **<span style="color: black; font-family: 'Arial','sans-serif';">Function: ** <span style="color: black; font-family: 'Arial','sans-serif';">Diffusion and filtration <span style="color: black; font-family: 'Arial','sans-serif';">Provide a slick, friction-reducing lining in lymphatic and cardiovascular systems **<span style="color: black; font-family: 'Arial','sans-serif';">Location: ** <span style="color: black; font-family: 'Arial','sans-serif';">Found in the kidney glomeruli, lining of heart, blood vessels, lymphatic vessels, and serosae <span style="color: black; font-family: 'Arial','sans-serif';">Example is lungs where we are going for blood gas exchange and want a flow of both from high to low concentration areas <span style="color: black; font-family: 'Arial','sans-serif';">Nucleus is stained. Can’t see much else in the cell because of the low organelle levels. The cells don’t have much work to do because diffusion is passive (not working against a pressure gradient so no pump) **<span style="color: black; font-family: 'Arial','sans-serif';">Simple Cuboidal ****<span style="color: #548dd4; font-family: 'Arial','sans-serif';">(Figure 4.3b, page 121) ** <span style="color: black; font-family: 'Arial','sans-serif';">Single layer of cube-like cells with large, spherical central nuclei **<span style="color: black; font-family: 'Arial','sans-serif';">Function: ** <span style="color: black; font-family: 'Arial','sans-serif';">In secretion and absorption **<span style="color: black; font-family: 'Arial','sans-serif';">Location: ** <span style="color: black; font-family: 'Arial','sans-serif';">In kidney tubules, ducts and secretory portions of small glands, and ovary surface <span style="color: black; font-family: 'Arial','sans-serif';">Cuboid shape limits diffusion <span style="color: black; font-family: 'Arial','sans-serif';">Offers some protection because cube shape gives some thickness <span style="color: black; font-family: 'Arial','sans-serif';">Absorption and secretion where the body does not have to work too hard **<span style="color: black; font-family: 'Arial','sans-serif';">Simple Columnar ****<span style="color: #548dd4; font-family: 'Arial','sans-serif';">(Figure 4.3c, page 120) ** <span style="color: black; font-family: 'Arial','sans-serif';">Single layer of tall cells with oval nuclei; many contain cilia <span style="color: black; font-family: 'Arial','sans-serif';">Goblet cells are often found in this layer **<span style="color: black; font-family: 'Arial','sans-serif';">Function: ** <span style="color: black; font-family: 'Arial','sans-serif';">Absorption, secretion where the body has to work at the task **<span style="color: black; font-family: 'Arial','sans-serif';">Location: ** <span style="color: black; font-family: 'Arial','sans-serif';">No-ciliated type line digestive tract and gallbladder <span style="color: black; font-family: 'Arial','sans-serif';">Ciliated type line small bronchi, uterine tubes, and some regions of the uterus <span style="color: black; font-family: 'Arial','sans-serif';">Cilia help move substances through internal passageways <span style="color: black; font-family: 'Arial','sans-serif';">Nucleus is often closer to basement membrane than apical surface **<span style="color: black; font-family: 'Arial','sans-serif';">Pseu ****<span style="color: black; font-family: 'Arial','sans-serif';">dostratified Columnar ****<span style="color: #548dd4; font-family: 'Arial','sans-serif';">(Figure 4.3d, page 122) ** <span style="color: black; font-family: 'Arial','sans-serif';">Has Goblet cells to make mucous and keep surface smooth as well as pick up unwanted substances found in trachea to clean **<span style="color: black; font-family: 'Arial','sans-serif';">Function: ** <span style="color: black; font-family: 'Arial','sans-serif';">Secretion and propulsion of mucus – so has Goblet cells (mucus secreting) to make mucous and keep surface smooth as well as pick up unwanted substances **<span style="color: black; font-family: 'Arial','sans-serif';">Location: ** <span style="color: black; font-family: 'Arial','sans-serif';">Found male sperm-carrying ducts (non-ciliated) and trachea (ciliated) – to clear away and found in fallopian tubes and uterus cilia propel egg to a good spot for implanting <span style="color: black; font-family: 'Arial','sans-serif';">Single layer of cells with different heights; some do not reach the free surface <span style="color: black; font-family: 'Arial','sans-serif';">Nuclei are seen at different layers <span style="color: black; font-family: 'Arial','sans-serif';">Usually has cilia <span style="color: black; font-family: 'Arial','sans-serif';">Stratified epithelium does not have cilia so if it has hairs then it is pseudo stratified **<span style="color: black; font-family: 'Arial','sans-serif';">Stratified Squamous ****<span style="color: #548dd4; font-family: 'Arial','sans-serif';">(Figure 4.3e, page 123) ** <span style="color: black; font-family: 'Arial','sans-serif';">Thick membrane composed of several layers of cells <span style="color: black; font-family: 'Arial','sans-serif';">Most wide spread of all epithelial tissue **<span style="color: black; font-family: 'Arial','sans-serif';">Function: ** <span style="color: black; font-family: 'Arial','sans-serif';">Protection of underlying areas subjected to abrasion **<span style="color: black; font-family: 'Arial','sans-serif';">Location: ** <span style="color: black; font-family: 'Arial','sans-serif';">Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (non-keratinized cells) – so this is pretty much anywhere that has an opening to the outside or is at places of high abrasion **<span style="color: black; font-family: 'Arial','sans-serif';">Stratified Columnar ** <span style="color: black; font-family: 'Arial','sans-serif';">Multi-layered tall <span style="color: black; font-family: 'Arial','sans-serif';">Stratified columnar - limited distribution in the body **<span style="color: black; font-family: 'Arial','sans-serif';">Function: ** <span style="color: black; font-family: 'Arial','sans-serif';">The cells function in [|secretion] and [|protection]. **<span style="color: black; font-family: 'Arial','sans-serif';">Location: ** <span style="color: black; font-family: 'Arial','sans-serif';">In the pharynx, male urethra and vas deferens, ocular conjunctiva (eye), parts of the any sand lining some glandular ducts like salivary glands <span style="color: black; font-family: 'Arial','sans-serif';">Also occurs at transition areas between two other types of epithelia <span style="color: black; font-family: 'Arial','sans-serif';">Rarest of all epithelial tissue <span style="color: black; font-family: 'Arial','sans-serif';">Stratified cuboidal <span style="color: black; font-family: 'Arial','sans-serif';">Quite rare in the body <span style="color: black; font-family: 'Arial','sans-serif';">Found in some sweat and mammary glands - and looks like the above but cells are square in shape <span style="color: black; font-family: 'Arial','sans-serif';">Typically two cell layers thick **<span style="color: black; font-family: 'Arial','sans-serif';">Transitional Epithelium ****<span style="color: #548dd4; font-family: 'Arial','sans-serif';">(Figure 4.3f, page 123) ** <span style="color: black; font-family: 'Arial','sans-serif';">Resembles both stratified and squamous and stratified cuboidal <span style="color: black; font-family: 'Arial','sans-serif';">Basal cells are cuboidal or columnar <span style="color: black; font-family: 'Arial','sans-serif';">Surface cells dome shaped or squamous like <span style="color: black; font-family: 'Arial','sans-serif';">Depends on degree of stretch **<span style="color: black; font-family: 'Arial','sans-serif';">Function: ** <span style="color: black; font-family: 'Arial','sans-serif';">Stretches **<span style="color: black; font-family: 'Arial','sans-serif';">Location: ** <span style="color: black; font-family: 'Arial','sans-serif';">Lines ureter, bladder and part of urethra <span style="color: black; font-family: 'Arial','sans-serif';"> **<span style="color: black; font-family: 'Arial','sans-serif';">Respiratory Tract ** <span style="color: black; font-family: 'Arial','sans-serif';">Respiratory tract is good place to see the structure change because of the need for functional change <span style="color: black; font-family: 'Arial','sans-serif';">Example is stratified in mouth where we need protection and simple squamous in lungs where we need a thin barrier for diffusion and pseudostratified ciliated columnar in air ways so that we can work to keep debris out of the lungs **<span style="color: black; font-family: 'Arial','sans-serif';">Epithelia: Glandular ** <span style="color: black; font-family: 'Arial','sans-serif';">A gland is one or more cells that makes and secretes an aqueous fluid <span style="color: black; font-family: 'Arial','sans-serif';">Classified by: <span style="color: black; font-family: 'Arial','sans-serif';">Site of product release – endocrine or exocrine <span style="color: black; font-family: 'Arial','sans-serif';">Relative number of cells forming the gland – unicellular or multicellular **<span style="color: black; font-family: 'Arial','sans-serif';">Endocrine Glands ** <span style="color: black; font-family: 'Arial','sans-serif';">Ductless glands that produce hormones <span style="color: black; font-family: 'Arial','sans-serif';">Secretions include amino acids, proteins, glycoproteins, and steroids **<span style="color: black; font-family: 'Arial','sans-serif';">Exocrine Glands ** <span style="color: black; font-family: 'Arial','sans-serif';">More numerous than endocrine glands <span style="color: black; font-family: 'Arial','sans-serif';">Secrete their products onto body surfaces (skin) or into body cavities <span style="color: black; font-family: 'Arial','sans-serif';">Examples include mucous, sweat, oil, and salivary glands <span style="color: black; font-family: 'Arial','sans-serif';">The only important unicellular gland is the goblet cell <span style="color: black; font-family: 'Arial','sans-serif';">Multicellular exocrine glands are composed of a duct and secretory unit **<span style="color: #548dd4; font-family: 'Arial','sans-serif';">(Figure 4.5, page 126) ** <span style="color: black; font-family: 'arial','sans-serif';">Classified according to: <span style="color: black; font-family: 'arial','sans-serif';">Simple or compound duct type <span style="color: black; font-family: 'arial','sans-serif';">Structure of their secretory units <span style="color: black; font-family: 'Arial','sans-serif';">Function and Structure <span style="color: black; font-family: 'Arial','sans-serif';">Exploring Epithelial Tissue Further <span style="color: black; font-family: 'Arial','sans-serif';">Review Questions <span style="color: black; font-family: 'Arial','sans-serif';">[|Moodle Assessment] <span style="color: black; font-family: 'Arial','sans-serif';">Content