Tissues Flashcards
What does Histology and Pathology mean?
Histology: histo = tissue; ology = study
* Histology: microscopic study of tissues
* Pathologist: physician that examines tissue to help other physicians
What is the Difference between Epithelial and Connective tissue?
Epithelial tissue
Has cells tightly packed together
Has little or no ECM
Connective tissue
Has a few scattered cells
Cells are surrounded by large
amount of ECM
What is Surface (Proper) ET?
- Forms surface layers and
- Avascular: does not have its own
blood supply - Provides coverings of skin and some
internal organs - Forms linings of vessels, ducts, and
body cavities - Body cavities such as:
interior of respiratory, digestive, urinary, and reproductive systems
What are the Classifications of Surface ET: number of cell layers?
- Simple ET (uni-laminar = one layer)
- Very thin -allows diffusion, osmosis and filtration and absorption to pass through
- Oxygen and carbon dioxide diffuse through simple ET in lungs
- Can function with absorption: absorption of fluids and other substances
- Stratified (two or more layers)
- More layers = more protection, etc.
- Appears where there is considerable wear and tear.
- Pseudostratified:
- Looks like more than one layer, but it’s not.
What are the Classifications of surface ET: cell shape?
Squamish cells:
* Think “thin” rapid passage of
substances through them
Cuboidal cells:
* Cube shaped secretion or absorption
Columnar cells:
* Taller than wide (like columns)
* protect underlying tissues (shock
absorbers) / absorption: have microvilli =
increase surface area for absorption
What are Transitional (Urothelium) cells?
Transitional (Urothelium) cells:
* Change shape: relaxed = Cuboidal / stretched = Squamish
* Example urinary bladder: cells can stretch to large size and collapse to smaller size
What is Glandular ET?
Glandular ET
Primary function is secretion
* Glands either endocrine or exocrine
*epithelium tissue that secretes substances (via ducts) onto either:
* A surface (exocrine)
* Into blood (endocrine)
What does all connective tissue have in common?
- Develop from same cell (Mesenchyme)
- They have different degrees of vascularity
- Connective tissues are mostly composed of non-living material (ECM)
What is ECM made up of?
EM (Jell-O) made up of two components:
1. Ground substance and
2. Fibers
All connective tissue cells (marshmallows) have
two phases. What are they?
- Immature phase
* Cells called “Blasts” (means forming)
* secrete ground substance and fibers
* Creates unique extracellular matrix - Mature phase
* Blasts mature into “cytes”
* Cytes maintain matrix health
What are the Connective tissues functions?
- Binds things together
- Supports and strengthens
- Protects
- Compartmentalizes structure
- Adipose tissue (a connective tissue type) = primary location of stored
energy reserves - Blood (a connective tissue type) = transport system to service cells
What is Ground substance?
Ground substance:
* Component between cells and fibers
* Supports cells, binds them together
* Provides medium for exchange between blood and cells
* role in tissues development/ functions
* Contains water and large organic molecules (polysaccharides and proteins) collectively known as GAG’s
* GAG’s trap water and make ground substance more jelly-like
What are the three types of ECM fibers?
Three types of ECM fibers
1. Collagen fibers
* Protein fibers: strongest and most abundant fibers (stronger than steel
of same size)
* Resist pulling or stretching
2. Elastic fibers
* Contain protein elastin
* Strong but can be stretched up to 150% then return to normal length
* Plentiful in skin
3. Reticular fibers
* Made of collagen arranged in bundles with a coating of glycoproteins
* Provide support for walls of blood vessels and form a supporting
framework around many “soft” organs (spleen, lymph nodes).
Connective tissue cells vary according to type of what?
Fibroblasts:
-Secretes fibers and ground substance
-Most common cell in connective tissue
Macrophages:
-Develop from monocytes (WBC) and destroy bacteria by phagocytosis
Plasma cells
-Part of Adaptive Immune System
Mast cells:
-Involved in triggering inflammatory responses (innate immune system)
White blood cells
-Not found in significant numbers in normal connective tissue
-Respond to infection/pathogens
Examples:
-neutrophils (gather at sites of infection)
-eosinophils (migrate to parasitic invasions)
-Adipocytes:
-Fat cells
-Store triglycerides
