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Lecture 3

PNB 2264 Lecture Notes - Lecture 3: Coagulation, Osteoclast, Fibroblast


Department
Physiology and Neurobiology
Course Code
PNB 2264
Professor
crivello
Lecture
3

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What is a tissue?
- Organized collection fo cells and non cell material
- How are they characterized?
o Cell type, physiological role, non cell material
- Types
o Muscle
o Connective
o Epithelial
o Nervous
How do cells stay together?
- Complex cell to cell connections
- Desmosomes
o Spot like adhesion, thick rivet, open intercellular path
- Adherens junction
o Strong interlocking belt between cells
o Cadherin protein
- Tight junctions
o Think of two pieces sewn together
o No intercellular path
- Gap junction
o Hole in the middle of the junction allows for movement of small molecules
o Still holds cells tightly
Why are there different kinds?
- Structure dictates function
- Different types of cell to cell connections must mean different functions
- Given that the skin is a protective barrier, it needs tighter junctions
Non cell material
- Extracellular matrix (ECM)
o Glycosaminoglycans
o Proteins
o Interstitial matrix
Cell types
- Stem cells
o Cells with a infinite ability to divide and provide differentiated daughter cells
o Identifies by
Morphology
Location
Proteins expressed on surface
- -blasts: creators of ECM
- -clasts: destroyers of ECM
- -cytes: living inside the tissue
Why does a stem cell stay a stem cell?
- Location
o Interaction between basement membrane and cell
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o Protein-protein interactions based on ECM
- This interaction causes stem cell to stay undifferentiated
Summarize
- Tissues are characterized by the cell type, ECM and their function
- Some tissues include stem cells that can renew the tissues if damaged
- Now lets discuss each tissue type
Epithelium
- Interesting facts
o 60% of all tissues
o waterproof barrier
o tight junctions
o polarized membranes apical, lateral and basal
o avascular feed by diffusion
o external and internal surfaces
o stem cells
o secretion and absorption
- why those properties?
o Tight junctions
o Basement membrane
o Polarized membrane
o Microvilli
o Special proteins
Keratin
Keratin
- family fibrous structural proteins
o found in skin, hair, nails
o form intermediate sized bundles that are tough and insoluble in water
o help together by cysteine-cysteine bond
Epithelial subtypes
- simple
o single layer
- stratified, pseudostratified
o multiple layers
- squamous
o star shaped
- cuboidal
o shaped like dice
- columnar
o shaped like column
Specialized epithelium
- mucosal and serosal
o mucosal is anything that makes mucus
o serosal makes a more watery substance (sweat glands)
- protection by keeping surfaces wet (dry surfaces crack)
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