Skin Flashcards
Function of skin (7)
1.Protection: resist penetration, abrasion & block foreign material
2.Containment: prevent body liquid lost
3.Thermoregulation: retention and dissipation of heat
4.Immunology defense
5.Sensory abilities
6.Communication
7.Appendages: nails, hair, sebaceous glands, sweat glands
Skin layers (3) and their characteristic
Epidermis: stems cells differentiate and going up and gradually keratinized
Dermis: reticular
Hypodermis: adipose tissue
4 layers +1structure in Epidermis
Describe cells in each layer+identify special structure
Stratum corneum: stratified squamous, keratinized epithelium; dead cells
Stratum granulosum: stratified squamous epithelium, contain keratohyalin granules
Stratum spinosum: polygonal cells connect by desmosome
Stratum greminativum: simple columnar epithelium
Basement membrane
Types of Epithelium
- Simple: squamous/cuboidal/columnar
- Stratified
-squamous(keratinized/non-keratinized)/cuboidal/columnar
-transitional - Pseudostratified
Types of Epithelium
- Simple: squamous/cuboidal/columnar
- Stratified
-squamous(keratinized/non-keratinized)/cuboidal/columnar
-transitional - Pseudostratified
What is epithelium tissue?
Epidermis
What is the layer between stratum corneum and stratum granulosum? And its function & position
Stratum lucidum: protect from fiction, palm
What is callus?
Partially differentiated keratinocytes, more keratin than stratum corneum
How to stain the basement membrane?
P.A.S (periodic acid-Schiff)
-Periodic acid change glucose to aldehyde, and stained by Schiff reactant
-Used for demonstrate carbohydrates, give sugar dark purple color
How to stain the basement membrane?
P.A.S (periodic acid-Schiff)
-Periodic acid change glucose to aldehyde, and stained by Schiff reactant
-Used for demonstrate carbohydrates, give sugar dark purple color
Components of BM (4)
1.Proteoglycans: core protein+GAGs (glycoaminoglycans) 50% sugar-50% protein
2.Glycoproteins: 10% sugar-90% protein
3.Collagen
4. A layer of reticular fibers underlies BM
collagen Iv(produced by epidermis cell) III(reticular fiber) VII (anchoring filaments)
Functions of Basal Lamina =BM (5)
- Structural attachment of epithelial cells to connective tissue
2.Compartmentalization: isolate epithelial cells and muscle cells
3.Filtration: in kidney
4.Help to maintain the polarity of the epithelial tissues
5.Tissue Scaffolding
Characteristics of all epithelial tissue (6)
1.Cells are closely associated with little extracellular space
2.Cells are strongly attached via intracellulaire junctions
3.Line body surfaces and body cavities
4.Specialization: absorption, secretion, sensation, contractility
5.Cells are polarized
6.Epithelial tissue rest on a basement membrane
Stratum granulosum
contain basophilic (blue) granules called keratohyalin granules (made of phosphorylated histidine-rich protein and cystine-containing proteins) that mature to become keratin.
Lamellar bodies: vesicles filled with wax and fatty acids and triglycerides (phospholipids) – when emptied in corneum, fuse to make lipid sheets (make us impermeable to water). Small black dots
Keratin: translucid scleroproteins formed b y6-8 polypeptides (40 000 – 70 000 kDa)
Glycoprotein in BM
Laminin
link surface of epithelial cells to the BM
Entactin (Nidogen-1)
essential for BM
Fiberonectin
bind PM to heparan sulfate
Melanocytes
intracalated into stratum germinativum
projections into spinosum
Ovoid shaped cell with irregular processes projecting upwards
Vesicle that holds melanin ( tyrosine which is transformed into 3,4-hydrocyphenylalanin, and then dopaquinon and at last melanin through biochemical pathway catalysed by tyrosinase)
Projections go past first layer into spinosum and break off and get phagocytosed by spinosum cells.
Melanin is released and makes a melanin umbrella (cover apical side) over nuclei to block UV rays (prevent DNA mutations)
Two types: Eumelanin (brown) and pheomelanin (red) – contributes to skin color
proteoglycans in BM
GAGs
hold water
anionic
