3.2 Flashcards
(15 cards)
What is the purpose of cell junctions?
- Connect cells and surrounding structures
- Anchor cells to each other
- Protect tissues from mechanical stress
- Facilitate communication
What are the 5 types of cell junctions
- Tight junctions
- Adherents junctions
- Desmosomes
- Hemidesmosomes
- Gap junctions
What are features of tight junctions?
- Fusion of plasma membrane proteins of adjacent cells
- no free space between cell membranes, form a water proof deal, strict control of pagan across membrane (force substance to pass through receptors on the cell membrane)
Located apically
Blood brain barrier, stomach and bladder
What are features of adherens junctions?
Membrane proteins ‘zipping-up’ adjacent cells.
Junctions connected to the inside of the cell via the cytoskeleton.
Hook like manner
Regulate cell shape
Stabilise cell contact
Hold tissue together
Located midway, down the cell wall, below tight junctions
What are features of desmosomes?
Protein fibres linking adjacent cells together
Similar to adherens
Provide mechanical strength and stability
Connect protein filaments of the cytoskeleton of adjacent cells.
Present in tissues sustaining high mechanical stress (skin, myocardium, bladder.
What are features of hemidesmosomes?
Half a desmosome
Protein fibres connect cells to the basement membrane
Found on the bottom of the basement cells
Skin
What are features of gap junctions?
Aligned Chanel protein pores between adjacent cells.
Rapid passage of small molecules
Cell communication
Sharing of nutrients
A sheet of epithelial cells functions in unison.
What 5 responses can the cell have under stress?
Atrophy, hypertrophy, hyperplasia, metaplasia and dysplasia
What occurs in the process of atrophy?
Decrease in cell size, shrinking of organ.
Loss of tissue in skeletal/cardiac muscle, brain
What occurs in the process hypertrophy?
Increase in cell size
Increase in cellular protein content
Bulking up of skeletal muscle due to weight bearing exercise
What occurs in the process of phperplasia?
Increased cell number due to increased proliferation
Increased tissue size
Cause by increase in demand (inflammatory response development state
What occurs in the process of metaplasia?
Transformation of one type of epithelium to another
Occurs in response to changes in the tissue environment
Reversible if original environment is restored
What occurs in the process of dysplasia?
Increase in the number of immature cells within a tissue
Characterised by appearance of cells of, abnormal shape, unequal size.
Early form / a pre-cancerous state.
What occurs in the process of neoplasia?
Uncontrolled cell proliferation
Loss of original cell function
Benign or malignant
How to cells go from normal to cancer?
Normal —> hyperplasia —> dysplasia —> cancer
