Identify the type of borders found on epithelial tissue. Bell Work: Identify the type of borders found on epithelial tissue.

Epithelial Function Location: Functions: Covers body Surfaces Lines body cavities Forms glands Functions: Secretion Selective absorption Protection Transcellular support Detection of sensation

Function Secretion Selective Absorption Protection When a cell produces substances and releases those substances into the environment. Ie. Digestive tract has high secretion Selective Absorption Epithelial tissue is in direct contact with the outer environment so it selects what materials come into and out of the cell Protection Tissue in contact with the external environment has to have a protective function to protect internal tissue Ie. Skin

Function Transcellular Transport Detection of Sensation Able to help substances travel through a certain distance Detection of Sensation Associated with nerve cells because epithelium can be found on the external part of the body; nerve cells receive stimuli

Epithelial Features Cells are usually joined together Little or no intercellular material Don’t have a lot of extracellular material around them

Classifications of Epithelia 5/23/2019 Classifications of Epithelia First the name of tissue indicates # of layers (3 types) 1. Simple – one layer of cells (extends from basement membrane to the apical surface) 2. Stratified – more than one layer of cells

Classification of Epithelia 3. Pseudostratified- tissue appears to be stratified, but all cells contact basement membrane so it is in fact simple

Classifications of Epithelia 5/23/2019 Classifications of Epithelia Last name of tissue describes shape of cells (3 types) 1. Squamous – cells wider than tall (plate or “scale” like) 2. Cuboidal – cells are as wide as tall, as in cubes 3. Columnar – cells are taller than they are wide, like columns

5/23/2019 Naming Epithelia Naming the epithelia includes the layers (first) and the shape of the cells (second) i.e. stratified cuboidal epithelium The name may also include any accessory structures Goblet cells, cilia, keratin, etc. Special epithelial tissues (don’t follow naming convention) Psuedostratified Transitional

https://www.youtube.com/watch?v=ux9rvC5NvQ8

How do you go about naming epithelial tissue? Do Now: How do you go about naming epithelial tissue?

Naming Practice!

Objectives: Describe the functions and locations of simple epithelial tissue. Describe the functions and locations of stratified epithelial tissue.

Simple Squamous Epithelium 5/23/2019 Simple Squamous Epithelium Description Single layer of flat cells with disc-shaped nuclei Special types Endothelium (inner covering) Slick lining of hollow vessels (blood & lymph) Mesothelium (middle covering) Lines abdominal, pleural, and pericardial cavities Covers visceral (internal) organs of those cavities (ie. heart, stomach, lung, etc.) Peritoneal (abdomen), pleural (lung), pericardial (heart) Visceral organs (heart, lungs, intestine, pancreas, spleen, stomach etc)

Simple Squamous Epithelium 5/23/2019 Simple Squamous Epithelium Function: Passage of materials by passive diffusion and filtration Secretes lubricating substances reducing friction in mesothelial membranes Location: Alveoli of lungs Lining of heart, blood and lymphatic vessels Lining of ventral body cavity (pericardium, pleural and abdominopelvic cavities) Ventral cavity (thoracic and abdominal cavities)

Simple Squamous Epithelium 5/23/2019 Small, flat cells arranged around large, empty circles (air sacs). May be confused with Adipose Tissue, but note the multiple cells and nuclei (arrows). Simple squamous lining the walls of the capillary

Simple Cuboidal Epithelium 5/23/2019 Simple Cuboidal Epithelium Description Single layer of cube-like cells with large, spherical central nuclei Function Secretion and absorption Location Kidney, secretory portions of small glands (ie. saliva and thyroid), ovary surface

Simple Cuboidal Epithelium 5/23/2019 Simple Cuboidal Epithelium Squarish cells with round nuclei in a single row (arrows), usually arranged in a circle (tubule).

Simple Columnar Epithelium Description Single layer of column-shaped (rectangular) cells with oval nuclei Some have cilia at their apical surface May contain goblet cells (secrete mucus) Function Absorption; secretion of mucus, enzymes, and other substances Ciliated type propels mucus or reproductive cells by ciliary action Scaffolding

Simple Columnar Epithelium Location Non-ciliated form Lines stomach, small and large intestine and gallbladder Ciliated form Lines bronchioles (in lungs), uterine (fallopian) tubes, and uterus Tall rectangular cells, with single, neat row of oval nuclei, usually more towards the base (in the bracketed row, the base is towards the top), leaving an apical region of nucleus-free cytoplasm. Note also goblet cells, found only here and in Pseudostratified Columnar Epithelium.

Do Now: Identify a location where simple squamous, cuboidal or columnar tissue is found?

Stratified Epithelia Layers: contain two or more layers of cells Regeneration: from Basal membrane Function: protection Naming: according to the shape of cells at apical layer

Stratified Squamous Epithelium Description Many layers of cells – squamous in shape Deeper layers of cells appear cuboidal or columnar Thickest epithelial tissue – adapted for protection

Stratified Squamous Epithelium Specific types Keratinized – contain the protective protein keratin Surface cells are dead and full of keratin Non-keratinized – forms moist lining of body openings Surface cells are living Function Protects underlying tissues in areas subject to abrasion Location Keratinized – forms epidermis (top layer of skin) Non-keratinized – forms lining of esophagus, mouth, and vagina

Stratified Squamous Epithelium Many layers (6 or more) of small, flattened cells. The only other epithelial tissue with so many layers is transitional (below), but note that stratified squamous epithelium typically has a more evenly contoured surface; with the uppermost layers of cells flattened. Non-keratinized vs. Keratinized

Stratified Cuboidal Epithelium Description Generally two layers of cube-shaped cells Function Protection Location Forms largest ducts of sweat glands Forms ducts of mammary glands and salivary glands

Stratified Columnar Epithelium Description several layers; basal cells usually cuboidal; superficial cells elongated Function protection and secretion Location Rare tissue type Found in male urethra and ducts, pharynx, and anus

Do Now: Identify a location where stratified squamous, cuboidal or columnar tissue is found?

Pseudostratified Columnar Epithelium Description All cells originate at basement membrane Only tall cells reach the apical surface May contain goblet cells and bear cilia Nuclei lie at varying heights within cells Gives false impression of stratification Function secretion of mucus; propulsion of mucus by cilia

Pseudostratified Columnar Epithelium Locations Non-ciliated type Ducts of male reproductive tubes Ducts of large glands Ciliated variety Lines trachea and most of upper respiratory tract Tall rectangular cells, with multiple irregular rows of nuclei (bracketed; compare to simple columnar, above). Note also goblet cells, found only here and in Simple Columnar Epithelium.

Transitional Epithelium Description Basal cells usually cuboidal or columnar Superficial cells dome-shaped or squamous Function stretches and permits distension of urinary bladder Location Lines ureters, urinary bladder and part of urethra

Transitional Epithelium Relaxed state Stretched state Numerous layers of cells of varying and often irregular shape, though generally not squamous (when unstretched as in the slides). Surface of tissue is folded (inside of ureter) or bumpy appearing (urinary bladder).

https://www.youtube.com/watch?v=ux9rvC5NvQ8

Do Now: Name three types of tissue, what they look at and a place where they can be found.

Glandular Epithelium Ducts carry products of exocrine glands to epithelial surface Include the following diverse glands Mucus-secreting glands Sweat and oil glands Salivary glands Liver and pancreas May be: unicellular or multicellular

Unicellular Exocrine Glands (The Goblet Cell) Goblet cells produce mucin Mucin + water  mucus Protects and lubricates many internal body surfaces

Types of Multicellular Exocrine Glands

Do Now: What are the two types of stratified squamous epithelial? Where can they be found?

Do Now: Where can simple cuboidal and stratified cuboidal be found? What is the difference in the function of each?