week 4 Flashcards
What must happen before specimens can be studied under microscope?
Specimen must be preserved and stained. Different parts of cells take up different dyes
acidic stains
negatively charged molecules
Basic stains
positively charged molecules
How are tissues stained for transmission electro microscopy? How does the stain work?
Heavy metal salts. Metals give contrast by deflecting electrons in the beams to different extents. Produces shades of grey because electron waves don’t have color.
scanning electron microscopy
3d pics of unsectioned tissue surface.
Artifacts
minor distortions in tissues caused by preservation
epithelial tissues
cover or line body cavities.
Types of epithelial tissues
- covering and lining membranes
- Glandular epithelium
Covering and lining epithelium
- Makes outer layer of skin
- lines body cavities
- covers organs and walls of organs
Glandular Epithelium
Fashions glands of body
T/F: Nearly all substances received or given off by the body must pass through and epithelium
True
Roles of epithelium
- Protection
- Absorption
- Filtration
- excretion
- Secretion
- Sensory reception
Five distinguishing characteristics of epithelium
- Polarity
- Specialized contacts
- Supported by connective tissue
4.Avascula but innervated - Regeneration
What is Apical-Basal Polarity of epithelium?
has apical and basal layers
Apical surface
not attached to surrounding tissue. Exposed to either outside of body or cavity of internal organ
basal surface
attached to underlying connective tissue
Most apical surfaces have
microvilli
microvilli
fingerlike extensions of plasma membrane. Increase surface area
Brush border
large amounts of microvilli found in absorbing or secreting tissues
cilia
tiny hailike projections that can help propel substances
basal lamina
noncellular, adhesive supporting sheet made of gycoproteins. Next to basal surface of epithelium. Filters which molecules from connective tissue can enter epithelium. Helps transport epithelial cells for wound repair
Specialized Contacts of epithelial tissue
except for glandular epithelium, epithelial cells fit cosely to make continous sheets. Joined by tight juctions and desmosomes.
All epithelial rest upon and are supported by ___________ tissue
connective
Basement membrane
Between epithelial and connective tissues