Cytology epithelial extra Flashcards
What types of collagen and other molecules does the basal lamina contain and its function
- Type 4 collagen
- laminin
-nidogen - Acts as a barrier sepearting the connective tissues from epithelial cells
What does reticular lamina contain
- type 2 and 7 collagen
What is the functions of intracellular junctions
- Communication
- Adhesion
- Sealing
Where is tight junctions located
and its function
- At the apical end
- It forms a seal between cells to prevent the flow of materials( to prevent paracellular transport)
What components does tight junctions contain
claudin and occluding proteins
What is the function of Desmosomes
- Provides firm adhesion and resilience against mechanical stress
What does components does desmosomes contain
- Desmoglein
-Desmoplakins
What does hemidesomes contain
- Integrins
What is the function of hemidesomes
- Attatch the basal domain of an epithelial cell to the subjacent basa lamina
What are the functions of gap junctions
- Allow the exchange of ions and small molecules
Where are adheren junctions
- Encircle cells below tight junctions
What are the functions of adherene junctions
- Links cells to a cytoskeleton networks
What is the function of necrosis
- ruptures cells and release their contents
What is the role of cytochrome C
- Activates caspases, initiating a cascade of protein degradation
What is the structure of intermediate filaments ?
coiled rod like diers that form anti parallel tetramers which assemble into large cable like bundkes
give examples of intermediate filaments
- Keratin
- Neurofilaments
What is the role of ribosomes?
They synthesize polypeptides by assembling amino acids
- They provide structural support
Explain the ribosomes subunits and what they include
- Ribosome has 2 subunits
-small subunit with rRNA and proteins
-Large subunit with multiple rRNA molecules and additional proteins
How are polyribosomes or polysomes formed?
- when multiple ribosomes bind to the same mRNA strand
Name the types of protein synthesis-
- Free polyribosomes
- ER associated polyribosomes
What is exocytosis?
A process where cells transport materials from their interior to the extracellular environment by vesicles that fues with the plasma membrane
Name the 2 pathways of secretion in exocytosis
- Constitiutive secretion
- Regulated secretion
What is constitutive secretion?
- A continuous process where vesicles deliver materials to the plasma membrane
Give an example of a substance delivered in Constitutive secretion
- Collagen subunits for the ECM
What is regulated secretion triggered by in exocytosis
- By signals such as the release of digestive enzymes in response to a stimuli
What is endocytosis
Cellular uptake process
What does endocytosis involve
- The cell membrane folding in to form vesicles that internalise macromolecules.
What are the three types of endocytosis
- Phagocytosis
-Pinocytosis
-Receptor-Mediated endocytosis
What happens in phagocytosis?
- It engulfs particles like bacteria using cell extensions.
phagosomes(vesicles) fuse with lysosomes for content breakdown
What happens in pinocytosis
- Small membrane invaginations trap extracelluar fluid, forming pinocytotic vesicles which either release contents across the cell or fuse with lysosomes
What happens in receptor-mediated endocytosis
- Cell surface receptors bind specific ligands, forming vesicles with clathrin coated pits .
- The vesicles then fuse with endosomes for degradation or content sorting
