Epithelial cells Flashcards
What are haemopoietic cells?
Blood cells, tissue-resident immune cells, and cells derived from bone marrow.
What are neural cells?
Cells that constitute the nervous system: Neurones (transmit electrical signals), and glial cells (provides neurone support and insulation - Schwann cell).
What are contractile tissues?
Skeletal muscle, cardiac muscle, smooth muscle.- Tissue with the ability to contract.
What are connective tissue cells?
Fibroblasts (many tissues), chondrocytes (cartilage), osteocytes (bones)- Connects, bind and supports tissue cells.
What are epithelial cells?
Cells forming continuous layers, layers line surfaces and separate tissues compartments- variety of alternative function- Secretion, selective absorption, protection, transcellular transport and sensing.
What are squamous epithelial cells?
Flattened, plate shape, abundant cytoplasm and small round circular nucleus.
What are columnar cells?
Arranged in columns; approximately 3000 microvilli per cell (maximises surface area for absorption). Simple columnar epithelial cells secrete molecules- enterocytes assist in molecular degradation in gut.
What are cuboidal cells?
Cuboidal: Cube-like (lines nephrons, ovaries and ducts)- main function is secretion.
What are stratified epithelium?
Multiple layers of cells
What are pseudo-stratified epithelium?
This epithelium appears to be multi-layered, but on close examination, the surface cells havecontactwith the basal lamina. e.g. airway (trachea and bronchi) epithelium, various ducts in the urinary and reproductive tracts.
What is epithelial cell polarity?
Different regions of the cell surface being different with discretely organised cellular contents. The discrete domains (formed by junctions) causes membrane polarity.
What is a lateral membrane?
Membrane is situated between two surfaces, membranes of adjacent membrane oppose each other
Why is polarity important?
Important for secretion of fluid, and solute transport
Directional flow and ion/cotransporter proteins
What are tight junctions?
Belt around apical lateral membrane (membranes of two adjacent cells accumulate together to form a barrier). Binding action prevents molecules from passing in between the cells.
What are adherens junctions?
Controls formation of other junctions. Junction holds adjacent epithelial cells together.
What are desmosomes?
Cell-cell anchoring junctions- provide mechanical stability as a result of strong cellular adhesives.
What are gap-junctions?
Allows various molecules and ions to pass between cells. Composed of two aligned connexons. Gap junctions allow for electrical communication between cells, and passage of second messengers.
What is exocrine secretion?
Exocrine secretion is the secretion of molecules within the duct or lumen
What is endocrine secretion?
Secretion directly into the blood
Which membrane do exocrine cells release secretions through?
Apical membrane
Which membrane do endocrine cells releases secretions into?
Basal membrane
What is constitutive secretion?
Secretory vesicles as they formed move directly to the plasma membrane, releasing their contents immediately
What is stimulated secretion?
Stored in cytoplasm within secretory vesicles, fusing with membrane upon stimulation
Which cells are produced within the small intestine?
Stem cells are present within the crypt of Lieberkuhn , replacing cells lost from the villus tip
How does hyperproliferation occur?
Cell production > cell loss, cells accumulate into a thick layer known as corns
What conditions cause hyper proliferation?
Frequent abrasions and pressure
Which virus causes hyper proliferation?
The papilloma virus, controls stratified squamous epithelium
