Lecture: Tissues Flashcards
Body Organization
Atoms→Cells→Molecules→Tissues
Histology
Study of Tissues
4 basic types of tissues
- Epithelial
- Connective
- Muscle
- Neural
Transmission Electron Microscope
“Transmits” electrons through the specimen
Scanning electron microscope
Produce a 3D image of the surface
Divisions of epithelial tissue
- Epithelia
- Glands
Epithelia has what kind of layers?
Avascular layers
2 types of glands
- Exocrine glands
- Endocrine glands
Exocrine glands function
Secrete onto external surfaces or into ducts
Endocrine glands function
Secrete hormones into interstitial fluid
What happens after the hormones are secreted into the interstitial fluid?
Hormones are then distributed by the bloodstream
Functions of Epithelial Tissues
- Provide physical protection
- Control permeability
- Provide sensation
- Produce specialized secretions
Neuroepithelium is found in which function of epithelial tissues?
Providing sensation
Neuroepithelium
Sensory epithelium found in special sense organs
What are the 2 surfaces?
- Apical surface
- Base
Apical surface
Faces exterior of or internal
Base
Attached to underlying tissues
Basolateral surface
Includes base and sides (lateral surfaces) attached to neighboring cells
Polarity (two sides to it)
Refers to structural differences between exposed and attached surfaces.
Apical surface features:
- Lumen
- Microvilli
- Cilia
Lumen
The apical surface is exposed to space inside the tube
Microvilli
Found on the surface of the digestive, urinary, and reproductive tracts
Cilia
Found on the surface in parts of the respiratory and reproductive tracts
Characteristics of epithelia
- Avascular
- Provide physical protection
- Provide sensation
- Provide secretion
- Highly regenerative
- Can have polarity
- Have specialized structures depending on location
What does epithelia lack?
Blood vessels (avascular)
Types of intercellular connections:
- Hemidesmosomes
- Tight (Occluding) junctions
- Adhesion belts
- Gap junctions
- Desmosomes
Hemidesomes
Attach to the deepest epithelial cells to BASEMENT MEMBRANE
What are hemidesmosomes made of?
- Base lamina (amorphous layer)
- Reticular lamina
Base lamina (amorphous layer)
- Contains glycoproteins and fine protein filaments
- Produced by basal surface of epithelium
Reticular lamina
- Contains bundles of coarse reticular protein fibers
- GIves strength and restricts diffusion
Connexons
Interlocked transmembrane proteins that hold gap junctions together
Gap junction function
Assist chemical COMMUNICATION to help coordinate functions
ex. secretion or beating cilia
Cell adhesion molecules (CAMS)
A thin layer of PROTEOGLYCANS may bond
What do des
