connective tissues proper Flashcards
Introduction to connective tissues and first type of connective tissue (proper) form, properties and function
Important characteristics
- Relatively few cells
- Large amount of nonliving substance (extracellular matrix):
- Ground substance
- Fibers
- Vascularized (except cartilage & blood)
Functions
- Support & protection
- Defense
- Transport & exchange
- Insulation & energy storage (fat)
Cell structure
- Derived from mesenchyme (detached cells in embryo)
- A characteristic type of cell for each kind of CT - Cells secrete extracellular matrix
- May also have other cells (e.g. defense cells)
Cell matrix structure (Fibers)
collegen, reticular and elastic
Collagen fibril
group of collagen
molecules bound together
Collagen fiber
group of collagen fibrils bound together
- Properties:
• Resists tension (pulling)
Like “steel cable”
Reticular fibers structure
• Each reticular fiber is made of specialized collagen fibrils - Made of Type III collagen molecules • Fibers are short, thin, branched What does “reticular” mean? Network. 
Resticular fibers properties
Forms delicate networks with lots of spaces • Allows smooth gliding / deformation
- Used at boundaries of tissue (e.g. surrounds capillaries)
Like a “folding trellis”
Elastic fibers Structure
• Main protein is elastin
- Coils up at rest
Like a “spring”
- Elastin molecules cross-linked in large groups to form a fiber (no fibrils)
Elastic fibers properties
• Highly elastic: i.e.recoilsto original shape
Genetic diseases of CT fibers
• Cutis laxa - Genetic defect in elastic fiber formation - Loss of elasticity in skin, joints • Ehlers-Danlos syndrome - Genetic defect in collagen fiber formation - Highly flexible skin, joints Both these diseases increase cardiovascular risks
Matrix ground substances
- Glycosaminoglycans (GAGs)
- Proteoglycans
- Interstitial fluid (tissue fluid)
- Additional components (e.g. calcium salts in bone)
Four classes of connective tissue
- Connective tissue proper
- Cartilage
- Bone tissue
- Blood
Connective tissue proper
• Relatively unspecialized – “classic” CT • Cells: Fibroblasts(secretematrix)-also
other cells
six types of connective tissue proper
varying in density & types of fibers: -
- Loose connective tissue ( areolar, adipose, reticular)
• Lots of ground substance, fewer fibers
- Dense connective tissue (regular, irregular, elastic)
• Lots of collagen fibers
Loose connective tissues
Aerolar, Adipose and reticular
Aerolar tissue
most widespread, “generic” CT -
- Gel-like matrix, lots of tissue fluid ( common to all CT)
- Adjoins all epithelia
- All 3 fiber types
- Has defense cells to fight infections
- Has fat cells to store energy
What is the role of areolar connective tissue in exchange:
look up in textbook
Adipose tissue
- Mostly fat cells
- Inhypodermis (superficialfascia) – located where?
- Also “visceral fat” around internal organs - Energy storage, protection, insulation
Reticular tissue
- The only fibers are reticular ( specialized collagen fibrils)
- Exclusively in lymphoid organs (spleen, red bone marrow, lymph nodes)
- Labyrinth used by defense cells
Dense regular connective tissue
- All collagen fibers run in 1 direction (axis) - Resists tension in 1 direction (axis)
- Tendons and ligaments
- Fascia (deep fascia)
Dense irregular connective tissue
Like areolar CT, but many more collagen fibers - Collagen fibers oriented in different directions
- Resists tension in different directions
- In dermis, and fibrous capsules of organs/joints
Elastic dense CT
- Most fibers are elastic fibers (also collagen fibers)
- Able to recoil after stretching
- Bronchial tubes in lungs; artery walls; some intervertebral ligaments
