Connective Tissue Flashcards
Connective tissue
Cells dispersed in an extracellular matrix, composed of ground substance and protein fibers.
Functions of connective tissue
Support and connect
Protection
Transportation
Energy storage
Proteins Fibers
Fibroblast: Cells that secrete ECM.
Collagen fiber: Most abundant in the body. Collagen 1.
Reticular fiber: Structural support to functional cells, blood vessels and nerves. Collagen 3,4.
Elastic fiber: Elastin stretch and recall.
Ground Substance
Space between cell and fiber.
- Multi-adhesive glycoproteins: Stabilize ECM and linking it to cells surface. Regulate cell migration.
- Glycosaminoglycans: Most abundant polysaccharide component of ground substance.
- Proteoglycans: Indirectly bind to hyaluronan.
Connective tissue cells
- Fibroblasts: Principal cell. Synthesis of all components of ECM.
- Macrophages: First line of defense from pathogens. Phagocytosis/inflammation.
- Mast cells: Develop in bone marrow and differentiate in connective tissue.
- Adipocytes: Store fat, become adipose tissue when accumulated in large numbers.
- Adult stem cells: Repair, formation of new tissue.
Connective tissue classification
Classified according to the characteristics of their ground substance and types of fiber found in the ECM
Types of connective tissue
Proper
Fluid
Supportive
Loose connective tissue proper
Low protein fiber content, high ground substance content.
Located under basal lamina of epithelia.
Provide nutrition to the epithelial layer above.
Site of inflammatory and immune reaction.
Dense connective tissue proper
Contains high levels of collagen fibers and low levels of ground substance.
Dense irregular connective tissue: Dermis. Collagen fibers have random orientation. Very strong.
Dense regular connective tissue: tendons and ligaments. Collagen fibers are parallel to each other.
What type of tissue are tendons and ligaments made of? (Exam)
Dense regular connective tissue proper
Connective tissue fluid
Blood
Lymph
Connective tissue supportive
Cartilage
Bone
Cartilage
Cells: Chondrocytes, secrete ECM and ground substance.
Avascular: No blood vessels (slow healing)
3 types:
Hyaline cartilage: Most common. Cover bones where they meet to form movable joints. Ribcage, nose.
Fibro cartilage: Tough, thick bundles of collagen. Intervertebral disc, menisci.
Elastic cartilage: Not important. External ear.
Bone tissue
Compact bone tissue
Spongy bone tissue
Compact bone tissue
External layer in all bones.
Contains structural osteon, or haversian system.
Located under periosteum.
Highly vascularized.
-Lamellae: concentric cylinders of matrix.
-Lacunae: Space in between lamellae where osteocyte reside.
-Canaliculi: small channels connecting lacunae and haversian together. Allows contact between osteocytes.
-Haversian canal: central canal with blood vessels.
Spongy bone tissue
Fills the epiphysis of long bone.
Trabecula: structural unit. Spikes forming along lines of stress.
Lamellae: concentric cylinders of matrix.
Lacunae: Space between lamellae where osteocytes reside.
Canaliculi: Small channels connecting lacunae.
Where hematopoiesis occurs.
Protects red bone marrow.
Bone tissue cells
Osteoprogenitor cells
Osteoblasts
Osteocytes
Osteoclasts
Osteoprogenitor cells
Bone stem cells
Under periosteum and endosteum.
Can differentiate into osteoblasts.
Osteoblasts
Form new bones. Synthesize and secrete collagen matrix and bone matrix proteins. Once trapped in matrix: -apoptosis -become osteocytes
Osteocytes
Mature bone cell enclosed by bone matrix.
Respond to mechanical load. Sense movement in interstitial fluid in lacunae and canaliculi.
Mechanical stress leads to bone matrix deposition.
Lack of mechanical stress leads to bone matrix reabsorption.
Osteoclasts
Not related to the others.
Reabsorption of bone matrix.
-Ruffled border: contact with bone tissue secretion of protons and hydrolytic enzymes.
-Clear zone: Tight seal with matrix.
-Basolateral region: exocytosis of digested material.
Bone quality
Total bone mass
Geometric distribution
Material properties
