Tissues 2-3 Flashcards
What are the three different cell shapes of epithelium?
Squamos, cuboidal and columnar
What is the function of tight junctions?
Allow cells to establish and maintain apical-basolateral polarity by preventing the mixing of proteins and lipids between different compartments.
What is the function of belt junctions?
Separate plasma membranes into apical and basolateral demains as they have different lipid and protein compositions.
What two cell types is protective epithelium made up of?
Keratinising (dead) and non-keratinising (alive) cells
Where do endocrine glands secrete into?
Bloodstream
Where do exocrine glands secrete into?
Ducts
Exocrine glands will have a high concentration of what?
Rough ER
What is constituted secretion?
Released as it is made
What is cell turnover?
A balance between cell proliferation and cell death. When it becomes unbalanced, polyps or cancers can develop.
How often does the lining of the gut get replaced?
Every 3-10 days.
How often is fat, heart and bone tissue replaced?
Every 8-10 years.
How does applying pressure affect cell proliferation?
Increases it.
What are the functions of the ECM?
- Physical support
- Determines mechanical and physiochemical properties
- Influences growth, adhesion and differentiation
- Essential for develop, tissue function and organogenesis
What is affected in OI?
Collagen type 1
What is affected in congenital muscular dystrophy?
Laminin 2
What is affected in Hurler’s syndrome?
ECM catabolism
What causes liver cirrhosis?
Excess ECM deposition
What causes osteoarthritis?
ECM loss
How many types of collagen is there?
28
What type of collagen is present in all basement membranes?
Type IV
What is the basic structure of collagen?
Triple helix made up of three alpha chains. X-Y-Gly repeat. X is often proline. Y is often hydroxyproline.
What are the effects of hydroxylation of proline and lysine?
Hydrogen bond formation between the three alpha chains. Form covalent cross linkages, providing tensile strength and stability.
What is scurvy caused by and what are the effects?
Vitamin C deficiency results in under hydroxylated collagen, reducing stability of tissue.
What is the structure of an elastic fibre?
Elastin core surrounded by microfibrils (rich in fibrilin)
What amino acids are elastic fibres rich in?
Alanine and lysine
What is a major risk for patients with Marfan’s syndrome?
Aortic ruptures due to lack of elasticity in blood vessels.
What is the basement membrane?
Flexible, highly specialised, thin mats of ECM underlying epithelial sheets.
Where is the basement membrane found?
Surrounds muscle, fat and peripheral nerve.
