Practical 2- Epithelia Flashcards
What functions do epithelia perform?
Barriers for protection/ containment e.g. skin/ bladder and a surface across which selective absorption/ secretion can take place e.g. the intestine, the breast.
What is simple epithelia? What is stratified epithelia? The cells in both are joined by what? They sit on top of what?
A single layer of cells mainly involved with secretion/ absorption.
Those composed of many layers of cells- mostly involved with protection.
Specialised junctions. Basal lamina (basement membrane.)
Simple columnar epithelia have what type of nuclei? These exhibit either of what 2 things at their apical surfaces? Where are these well developed?
Oval nucleus whose long axis is perpendicular to the base of the cell. Microvilli or cilia. Former= gut enterocytes and latter= on many of the cells of the respiratory tract.
Are there more or less goblet cells in the large compared to the small intestine? What colour do these stain?
More goblet cells. Pale-staining.
Microvilli are collectively known as what if they can’t be seen individually under light microscopes? What carbohydrate-rich substance is attached to their outer surface? Under what process does this stain heavily? What else stains heavily?
A brush border. Glycocalyx. The PAS procedure- dark magenta. Basement membrane and epithelium containing glycoproteins.
Where is ciliated epithelium found in the body? What does this normally consist of? Number of cilia per cell? Where is ciliated epithelium also found?
The airways of the nose, larynx and bronchial tree. A simple columnar epithelium with a mixture of ciliated cells and goblet cells. 300. In fallopian tubes to transport ova to the uterus.
What is cuboidal epithelium? Where does simple cuboidal epithelia occur in the body?
Appear square in profile with a round nucleus that is typically found in the centre of the cell. Ducts of glands e.g. sweat glands, salivary glands, pancreas and in kidney where form most of nephron.
Where are squamous epithelial cells found? These layers are kept moist by what? Simple squamous layer also lines what?
The outer surface of most thoracic and abdominal organs= ‘serosa.’ Similar layer also lines inside of pleural and peritoneal (abdominal) cavities.
A watery serous exudate which prevent organs from sticking together. Alveoli.
The septa that forms the walls of the air sacs of the lung are composed of what?
Capillaries covered by a thin layer of simple squamous alveolar cells= type 1 pneumocytes.
Where is stratified squamous epithelia found? In its keratinised form it forms what? The surface is kept moist by what?
Lining the mouth, throat, oesophagus, anus and vagina. The epidermal layer of the skin. The secretion of glands and by a fluid that exudes through the layers of cells.
In all stratified epithelia, the cells are replaced from where? What happens when they reach the surface? What is pseudo-stratified epithelia?
From below- the stem cells lie in the basal layer. The cells are eventually discarded (sloughed off) from the uppermost layer. This appears stratified, but is more akin to a simple epithelia.
What two layers does the skin have? The epidermis is composed of what? The lower layers are similar to what? The upper layers produce proteins which interact with what to produce keratin? This is what?
An outer epidermis and a deeper dermis. A stratified squamous keratinising epithelium. A moist stratified epithelium. The cytoskeleton of the cells. A dense protein that fills the cytoplasm of cells rendering them tough and waterproof.
Once filled with what, cells tend to do what? What is the blue staining granules layer below the keratinised squames?
Die and become detached from the underlying layers and are sloughed off. Blue keratohyaline granules which are precursors of keratin.
Where is pseudo-stratified epithelia found? In the contracted state, it appears what? What 2 features distinguishes it from normal stratified epithelia?
Lining the trachea and bronchi. Multi-layered but when stretched is reduced to a single layer of cells. All cells have direct contact with the basement membrane and cells are replaced by lateral migration rather than vertical.
What are the 3 types of cell-to-cell contact?
Desmosomes, tight(adherent) junctions and gap junctions.
