Lecture 5: Cell adhesions and membrane trasnport Flashcards
What are the three ways cells are held together?
- Cell adhesion molecules (CAM)
- Extracellular matrix (ECM)
- Specialized cell junctions
What is the Extracellular matrix?
- meshwork of fibrous proteins in the interstitial fluid
True of False interstitial provides a pathway for diffusion of nutrients, wastes, and other soluble traffic between the blood and tissue ?
true
What are the three types of proteins found in the extracellular matrix?
- Collagen
- Elastin
- Fibronectin
What does collagen do in respect to the ECM?
- forms cable like fibers
- gives tensile strength
True or false
Collagen weights 1/2 the amount of the total body protein weight?
true
What does elastin do in respect to the ECM?
- rubber like protein fiber
- allows stretching and and recoiling
Would the lung have more elastin than the skin?
yes it’s need more for the stretch factor when breathing
What does Fibronectin do in respect to the ECM?
- Promotes cell adhesion
- holds the cell in place
Reduced levels of what is related to tumor metastasis?
Fibronectin
Name the three types of specialized junctions and their main function:
- Desmosomes - adhering
- Tight Junctions - impermeable
- Gap junctions - communication
What is the function of the Desmosomes?
- anchors two cells together
that provides two cells with the strongest form of adhesions
How do desmosomes work?
- we add proteins called intercellular filaments which will connect the two cells together
- than we use intracellular keratin proteins to attach tp the plaque and weave through the entire cell
- the desmosomes are attached to both inter and intra cellular filaments
In what kind of cell would we find lot’s of desmosomes?
uterus
What is the function of Tight junctions?
for cells to have nothing in between them (sewing them together)
- created an impermeable barrier
In what kind of cell would we find lot’s of tight junctions and where in our body ?
columnar epithelium cells, in the lining of the intestine
What is the function of gap junctions?
for cells to communicate at an instantaneous rate
In what kind of cell would we want gap junctions
- muscle cells
- heart / cardiac cells
True or False?
Connecting tunnels are called connexons? (wheres ions go from one cell directly to another without crossing the extracellular space)
true
What is permeability?
means molecules can pass freely a given membrane
What is impermeability?
means molecules cannot pass freely though given membrane
Are molecules either 100% soluble or non soluble?
no, generally they are somewhere in between
What can pass easily through the plasma membrane?
- O2
- CO2
- Fatty acids
- anything lipid soluble
- non-polar molecules
What cannot pass easily through the plasma membrane?
- ions
- proteins
- glucose
does the size of a particle have an effect on the speed at which is crosses the plasma membrane?
yes
What is active force?
forces that require the cell to expend energy
What is passive force?
forces that do not require the cell to spend energy
