Lecture 5 - Tissues, Organs And Systems Flashcards
What is a tissue?
A group of structurally similar cells that function together as a unit
What 4 things holds cells together?
Cell to cell adhesion molecules
Extracellular matrix proteins (fibres)
Internal-external scaffolding
Close proximity (pressure effects)
What do epithelial cells normally rest on top of?
Basement membrane between them and A supporting bed of connective tissue
What usually separate epithelial cells and the supporting bed of connective tissue?
A basement membrane
What is the definition of an organ?
Multiple tissues coming together
How are epithelial cells held together?
Through epithelial cell adherence systems
Where are adherence systems found on/in an epithelial cell?
The lateral surface
The basal surface
What is the role of the adherence systems found on the lateral surface of an epithelial cell?
Joins epithelial cells to epithelial cells
What is the role of the adherence systems found on the basal surface of an epithelial cell?
They join the epithelial cell to the basement membrane
What 4 epithelial adherence systems are located on the lateral surface of the epithelial cells?
Tight junctions
Adherens junctions (cadherins)
Desmosomes
Gap junctions
What is the function of the tight junction adherence system? (Lateral surface)
Seals neighbouring cells together in an epithelial sheet to prevent the leakage of molecules between the cells
What is the function of the Adherens junction adherence system? (Lateral surface)
(Cadherins)
Joins an actin bundle in one cell to a similar bundle in a neighbouring cell
What is the function of the Desmosome adherence system? (Lateral surface)
Joins the INTERMEDIATE filaments in one cell to those in a neighbour
What is the function of the gap junction adherence system? (Lateral surface)
Allows the passage of small water soluble ions and molecules
Allows for very quick communication between cells
Which of the lateral surface adherence systems is the strongest
Desmosomes
What are the 2 important adherence systems located on the basal surface of epithelial cells?
Hemidesmosomes
Focal adhesions (Integrins)
What is the function of the hemidesmosome adherence system? (Basal surface)
Anchors intermediate filaments in a cell to the basal lamina
What is the function of the focal adhesion adherence system? (Basal surface)
(Integrins)
Anchors actin filaments in a cell to the basal lamina
Which of the 2 adherence systems joins actin?
Adherens junction (Lateral surface) cadherins
Focal adhesion (Basal surface) Integrins
So cadherins and Integrins join actin, Cadherins actin cell to cell and Integrins actin from cell to basement membrane
Which of the 2 adherence systems join intermediate filaments?
Desmosomes (Lateral surface)
Hemidesmosomes (Basal surface)
What adherence system is very important for communication between cells that can touch each other?
Gap junctions
How do tissues adhere to other types of tissues?
Through connective tissue fibres
What is the 2 main functions of adherence proteins?
Maintain survival and structure of the cells and tissues
Prevent pathogenic entry into the internal environment
What is the definition of a Mucosal Membrane?
The moist, inner lining of some organs and body cavities
What do the glands in the mucous membrane produce
Mucus
Where do musical membranes line?
GI Tract
Urinary Tract
Respiratory Tract
Urogenital tract