Epithelial tissue Flashcards
Definition of a tissue
is a grouping of similarly specialised cells united in the performance of a particular function.
what are the 4 types of tissue
epithelial
connective
muscle
nervous tissue
what are the types of epithelial tissue
- lining
- glandular
- sensory
- myoepithelium
- germinal
describe myoepithelium
these are muscle cells and contractile cells in glands contract and allow secretion into the duct
describe the sensory epithelial tissue
forms part of the smell and sensory system nerves
describe the germinal epithelial tissue
ovarian surface epithelium, a layer of cells covering the ovary and present in sperm, this is where zygotes are formed
what are the major two types of the epithelial tissue
- lining
- glandular
what are the characteristics
- Cellular polarity – basal v apical
- Polarity means that each cell has a top and bottom, the bottom is called the basal and the top is called the apical.
- The basal sits on the basement membrane in a single layer, if it is in a multiple layer than only the bottom sits on the basement membrane and the more mature move away,
- On the apical surface the epithelial cells are more specialised for example they may have cilia this increases the surface area, they may also have cilia present this helps them move and is powered by ATP
- Sit on a basement membrane; cell surface specialisations - Intercellular junctions – tissues have high cellularity (cell density) and are linked by junctional complexes
- High regenerative capacity, this is in response to damage; they have metaplastic potential which is when one form of epithelium changes to become another form
- They are produced and die very quickly usually in 3-5 days, replaced by new cells that come up and take there place - Avascular, this means that they have no blood vessels within the tissues but are innervated which means that nerve fibres can go between cells
- There are blood vessels present underneath and nutrients diffuse upwards, - They are supported by connective tissue
what does morphology mean
morphology of cells means the shape of the cell
what does it mean if the lining epithelial is simple
means there is only one layer
what does it mean if the lining epithelial is stratified
it means has more than 1 layer of tissue
if stratified what do we look at
- look at the surface layer which is the top layer
- If it is in a tube we look at the cell closest to the lumen
what are the types of epithelial tissue
- Simple squamous (flattened)
- Simple cuboidal – less active so nucleus is higher up
- Simple columnar – rectangle in shape and have the nucleus towards the bottom
- Pseudostratified columnar
describe the cell when it is active
When cells are active the cytoplasm is towards the apical end and the nucleus is towards the bottom such as simple columnar epithelial
describe the simple squamous tissue
single layer of flattend cells with disc shaped central nuclei and sparse cytoplasm
describe the function of the simple squamous
allows passage of materials by diffusion and filtration in sites where protection is not important, secres lubricating substances in serosae
describe the location of the simple squamous tissue
– kideny glomeruli, air sacs of lungs, lining of heart, blood vessels, lining of ventral body cavity, lymphatic vessels
describe the special names for the simple squamous tissue
- Called endothelium when lines blood and lympathic vessels
- Called mesothelium when it lines closed body cavities such as around the heart, the lungs and most of the abdominal contents
describe the function, location and special names of the simple squamous tissue
- Description – single layer of flattend cells with disc shaped central nuclei and sparse cytoplasm
- Function – allows passage of materials by diffusion and filtration in sites where protection is not important, secres lubricating substances in serosae
- Location – kideny glomeruli, air sacs of lungs, lining of heart, blood vessels, lining of ventral body cavity, lymphatic vessels
- Called endothelium when lines blood and lympathic vessels
- Called mesothelium when it lines closed body cavities such as around the heart, the lungs and most of the abdominal contents
describe the simple cuboidal tissue
single layer of cubelike cells with large spherical central nuclei
- This lines tubes and ducts
- Less active
- Larger nuclues
- There is some in the kidney where they are a bit more active
describe the function of the simple cuboidal tissue
secretion and absorpiton
describe the location of the simple cuboidal tissue
kidney tubules, ducts and secretory portions of small glands, ovary surface
- Mainly used in the trasport of bile
- Sometimes you don’t see the cells as other tubules are lined with cells that have greater amounts of cytoplasm so there are fewer seen lining the tubule in a cross section
describe simple columnar
single layer of tall cells with round to oval nuclei, some cells have cilia and the layer may contain mucus secreting unicellular glands
- Columns are elongated and the nuleus is towards the bottom as they are more active
describe the function of simple columnar
absorption, secretion of mucus, enzymes and other substances ciliated type propels mucus by ciliary action
- In the digestive tract cells do not have cilia but the enterocytes have another cell surface speiclisation which acts to increase the surface area of each cell, with increased luminal surface area each cell can help digestion and absorption of nutrients, electrolytes and water, these are called microvili