Epithelial cells Flashcards
What are the three constituents of the Cytoskeleton?
Microtubules
Intermediate filaments
Microfilaments
How thick are microtubules?
20nm
What are four functions of microtubules?
Maintain cell shape
Act as tracks for movement of cellular components
Major component of Cillia/Flagella
Form mitotic spindles
What is the arrangement of microtubules in cillia?
9+2
9 microtubule doublets and 2 central microtubules
What is the diameter of intermediate filaments?
10-15nm
What do intermediate filaments do?
Give cell mechanical strength
Involved in desmosome cell-cell adhesion
What is the diameter of microfilaments?
5-9nm
What are microfilaments made out of?
Globular actin polymer
What are microfilaments involved in?
Cell shape and movement
How many cells are there in an average human body?
37 trillion
How many types of cell types are there?
~200
What are the five main cell groups?
Connective tissue Contractile tissue Haematopoietic cells Neural cells Epithelial cells
What types of tumour originate from these cell types: Mesenchymal (connective/muscle) Haematopoietic Neural Epithelial
Mesenchymal (connective/muscle): Sarcomas
Haematopoietic: Leukaemias, lymphomas
Neural: neuroblastomas, gliomas
Epithelial: carcinomas
What is the extracellular matrix?
Matrix deposited by cells and forms insoluble extracellular environment, composed of fibrillar proteins in hydrated gel, and organisation depends on location
Name the five types of Cell-Cell junction
Tight Junction Adherans Junction Desmosome Gap Junction Hemidesmosome
How are Cell-Cell junctions typically arranged?
In apical junction complex in epithelia
Zonulae (belts)
Maculae (spots)
What us the Tight junction?
“belt junction” sealing strands of occludin form a network of contacts, acts to seal paracellular pathways and segregate apical/basolateral membrane polarity
What is the adhesion belt?
“belt junction”; transmembrane cadherin molecules associate with each other and to the actin cytoskeleton of their cell to join the bundles in one cell to the next; controls assembly of other junctions
What are desmosomes?
“spot junction”; cadherin-like molecules join the intermediate (keratin) filament cytoskeleton at spots; provides good mechanical continuity between cells
What is the gap junction?
“spot junction”; continuous pores between membranes - affected by pH, [Ca2+] and voltage so can open and close to control communication; allow passage of ions and small molecules between cells
What are hemidesmosomes?
“spot junction” join the cell to the basal lamina
Whats the acronym for remembering all the C-C junctions?
TADGH
That arsehole don’t get hate!
