Exam 2 - Glycocalyx and ECM Flashcards
What is the glycocalyx and what is it made of?
EC surface of cells; made of glycoproteins and glycolipids.
“Membrane decoration”
What is the ECM secreted by?
Cells that interact with it.
Is the ECM a part of the cell?
no
What are glycoproteins?
Polypeptides conjugated to polysaccharides
Which portion of the glycoprotein is associated with the membrane?
protein portion
What determines the height and thickness of the glycocalyx?
Saccharide portion
What are glycolipids?
Polysaccharides bound to membrane lipids
What are the most complex glycolipids?
Gangliosides
What is important about gangliosides?
They play a large role in immunology and are a receptor for bacterial toxins
What are the 3 functions of the glycocalyx?
- Protective barrier
- Immune recognition of self
- Intercellular adherence
What does the glycocalyx protect the cell from?
Bacterial invasion
What are two examples of glycocalyx functioning as intercellular adherence?
- Early adhesion events during tissue formation
2. Blood clot formation
What is the difference in structure between A/B antigens and O antigens?
A and B antigens are O antigens with additional saccharides attached to them.
What are the 3 human blood group antigens?
A, AB, O
What is the relationship between the glycocalyx and digestive enzymes?
Enzymes attach to the glycocalyx to digest food coming in
What part of the glycocalyx increases the surface area of intestinal cells?
Height and density
What does the glycocalyx on absorptive intestinal cells provide a barrier against?
Bacteria
Why are antigen sampling cells more susceptible to Salmonella infection?
They sample inside of the gut
Where does the H5N1 avian flu attach in birds?
Glycoproteins act as attachment sites in the mid-region of lungs
How does the H5N1 avian flu spread from birds?
Can be coughed out
Where does the H5N1 avian flu attach in humans?
Glycoproteins act as attachment sites deep in the lungs
How does the H5N1 avian flu spread from humans?
It doesn’t; replicated virus cannot be coughed out
Where are most animal cells embedded?
ECM
What type of tissue is the ECM most prominent in?
Connective tissue
What is the ratio of ECM to cells in c.t.?
ECM more plentiful than cells
What are the 3 components of ECM in c.t.?
- Fibers
- GAGs (most attached to proteoglycans)
- Other proteins
What are proteoglycans?
Protein core with carb chains attached (GAG chains)
- There are many different types
What largely determines the function of proteoglycans?
Associated GAG chains
What are the 2 main functions of proteoglycans?
- Attract water; provide well-hydrated matrix
2. Withstand compressive forces
What is an example of a GAG discussed in class?
Hyaluronic acid
Where is hyaluronic acid found?
ECM in dermis
What are the 2 functions of hyaluronic acid?
- Pulls in water
2. Helps to “plump up” skin
What animal has an overproduction of hyaluronic acid and what happens?
Sharpei; wrinkled and slimy skin
What are the 2 fiber types found in ECM?
- Collagen
2. Elastic
Where is collagen synthesized and where is it assembled?
Synthesized in the cell; assembled extracellularly
What determines the forces that can be tolerated by tissue?
Arrangement of collagen fibers
Between dense irregular c.t. and dense regular c.t., which is strongest?
Dense irregular
What is Ehlers-Danlos Syndrome?
Defect in collagen synthesis
How does Ehlers-Danlos Syndrome present?
Cutis hyperelastica
What is cutis hyperelastica?
Defect in collagen in the dermis
What are elastic fibers made up of?
Network of elastin molecules
What is the structure of elastic fibers when relaxed?
Fibers coiled and attached to one another
What are 3 types of tissues/organs that have elasticity?
- Skin
- Aorta
- Lung
What breaks down elastin?
elastase
Where is elastin found in the lungs?
Around alveoli
What does excessive elastase production result in?
Emphysema; alveoli cannot contract when a breath is released
