Lecture 1 Connective Tissue Flashcards
Is connective tissue exposed to the outside?
No. CT is never normally exposed to the outside. It is always covered by an epithelium
Are CT cells in contact with one another?
Connective tissue is made up of individual cells scattered within an extracellular matrix, which is a gel- like substance that also has protein fibers in it.
Roles; carries O2, CO2, nutrients and wastes
What is the ECM?
- A gel-like substance that has protein fibers in it.
- Carries O2, CO2, nutrients and wastes.
What are the types of connective tissue?
- Embryonic CT
- Adult CT (adult connective tissue is fibrous; it can be loose, dense irregular and dense regular)
- Special: adipose, cartilage, bone and hematopoietic.
Fx of connective tissues
- Framework for the body
- Protection
- Supports and interconnects other tissues
- Stores NRG
- Transports fluids, cells and dissolved chemicals throughout the body
- Defends against microorganisms
What type of cells are found in connective tissue?
- Fibroblasts
- Mesenchymal cells
- Adipocytes
- Chondro[cytes]
- Osteo[blasts]
- Hematopoietic stem cells
What are fibroblasts?
Fibroblasts make up a majority of the ECM. They make
- Collagen
- Proteoglycans
- Glycoproteins
What are mesenchymal cells?
They are connective tissue stem cells.
What are adipocytes?
They store and release fat.
What are chondrocytes?
Make cartilage
What are hemapoetic stem cells?
make RBCs and immune cells
Describe the fibrous component of the extracellular-matrix.
Fibrous part of the ECM is made up of:
- Collagens (type 1 is the most common), which resists tension
- Elastin (a stretchable fiber made up of tropoelastin, fibulin-1 and fibrillins 1 and 2)
- Reticular fibers that form a supportive meshwork.
Describe type 1 collagen fibers?
collagen fibers that are aligned and crosslinked to increase tensile strength
What is Scurvy?
Scurvy is a vitamin C deficiency.
Vitamine C is a cofactor needed for collagen to cross-link. Thus, people with scruby often have weak CT.
Ehlers Danlos Syndrome
Collagen is made abnormally, causing it to be WEAK. Thus, the CT is weak.
What is Marfans Syndrome?
Marfans sydrome is an autosomal dominant syndrome where elastin is weak due to a mutation in fibrillin-1.
This targets ocular, skeletal and cardiovascular systems. Patients tend to have cardiovascular anomalies, and tend to be tall with long arms and legs.
Incidence of Marfans
2-3/10k.
Describe the amorphous ground substance of the ECM.
It is made up of
- Proteoglycans (chondriotin, heperan, and keratan sulfates)
- Hylauronan
- Glycoproteins (cytokines, growth factors and structural proteins)
- Extracellular proenzymes.
How do cells interact with the ECM?
The cell and ECM interact via
integrin receptors, syndecans, CD44, selectins, dystroglycans, growth factor receptors and cytokine receptors.
Describe embryonic connective tissue?
Embryonic connectibve tissue is RICH in ECM and mesenchymal stem cells.
It has some, but not many collagen or reticular fibers.
In the umbilical cord, embryonic connective tissue can be referred to as what?
Warton’s Jelly. It is firm because it is rich in ECM.
What are [adult mesenchymal stem cells]?
Multipotent stem cells that can be made into fibroblasts, muscle cells (skeletal and smooth), osteoblasts, chondrablasts and adipocytes.
Thus, adult mesenchymal stem cells are more restrictive than embryo.