Connective Tissue Flashcards
Types of Connective Tissue
Connective Tissue Proper
Cartilage
Bone
Blood
Bone Marrow
Components of Connective Tissues
Cells
Fibers
Ground Substance
Matrix
Fibers + Ground Substance
Ground Substance (characteristics)
GAG (glycosaminoglyans)
Hydrated semisolid gel
Fills space + has proteins!
High viscosity (slow foreign particles)
Glycosaminoglycans (GAG)
Repeating disaccharides (sugars) that are key component in connective tissue ground substance
Proteoglycans (+types)
Proteins sulfated w/ glycosaminoglycans
-Hyaluronic Acid
-Chondroitin-4-sulfate & Chondroitin-6-sulfate
-Dermatan sulfate
-Keratan sulfate
-Heparan sulfate
Hyaluronic Acid
Most abundant GAG
Function: lubrication
Location: umbilical cord | synovial fluid | vitreous humor | cartilage
Chondroitin-4-sulfate & 6-sulfate (location)
Cartilage | bone | skin
Dermatan sulfate (location)
Skin | tendons | sclera | lungs
Keratan sulfate (location)
Cartilage | bone | cornea
Heparan sulfate (location)
Aorta | liver | lung | basal lamina
Cell Types in Connective Tissue Proper
Fixed Cells (FRAPMF)
no change in site
Wandering Cells (FPMEL)
change site, attracted where needed
Mesenchymal Cells
Structure: Processes | No fibers | Large, oval nuclei | irregular shape | few organelles
Function: give rise to other cell types
Fibroblasts / Fibrocytes
More specialized than mesenchymal
Most common cell in Loose CT
Function: wound repair | blast=create matrix
Reticular Cells
Structure: create “network” (spiderweb)
Function: secrete reticular fibers
Adipocyte
Function: Lipid-storing cell
Location: All Loose CT | predominant in adipose tissue
Pericytes
Structure: Change to smooth muscle or adipocytes (based on need)
Function: Endothelial cell support
Fixed Macrophages
Migrate, then stational (Blood–>CT)
Liver –> Kupfer cell
Nervous –> Microglia
Lung –> Alveolar Macrophages
Free Macrophages
“Wandering” cells
Structure: large | round | “foamy” cytoplasm | basophilic
Function: phagocytosis | repair (accumulate @ injury, ingest debris)
Plasma Cells
Structure: oval | basophilic
Function: secrete antibodies
Location: lymph nodes | GI | respiratory | female repro
Mast Cells
Structure: filled w/ granules (histamine | heparin | ECF-A release)
Function: secrete vasoactive compound | inflammatory/allergy response
Location: Loose CT of skin/intestine | around vessels
Eosinophils
Type of WBC
Function: immune reaction | phagocytosis of antigen-antibody complex | kill parasites by granule release
Lymphocytes
Type of WBC
Function: create antibody-producing cells
Fiber Types
Collagen Fibers
Elastic Fibers
Reticular Fibers
Collagen Type I Fiber
Structure: very strong | most abundant type | acidophilic | formed from protein “collagen” | striation (spaces)
Location: tendons | ligaments | organ capsules
Collagen Type I Fiber Synthesis (process)
- Fibroblasts form procollagen (soluble) into triple helix
- Transport out of cell | Cleave nonhelical ends = tropocollagen (insoluble)
- Tropocollagens aggregate = collagen fibrils –> fibers
- Collagen cross-links = striation
Collagen Type II Fiber (location)
Cartilage
Collagen Type III (location)
Arteries | GI | lymph lamina | reticular lamina of BM
Collagen Type IV (location)
Basal lamina of BM
Collagen Type VII (location)
Connect basal lamina to reticular lamina of BM
Basement Membrane parts
BM = basal lamina + reticular lamina
Basal lamina (derived from…)
Epithelium
Reticular lamina (derived from…)
Connective Tissue
Collagen Defect Disorders
Human: Osteogenesis imperfecta | Ehlers-Danlos Type 4,6,7 | Scurvy
Vet: Cutaneous Asthenia | Ehlers-Danlos analog | HERDA (Hereditary Equine Regional Dermal Asthenia)
Elastic Fibers
S: Retain shape after stretch | thinner than collagen | made of collagen type I fibrils | rubber-like
Components: elastin (protein) | microfibrils | collagen type I fibrils (surrounding)
Location: artery wall | respiratory | vocal cords | stretch ligaments | skin | gut
Elastic Fiber Synthesis
- Fibroblasts secrete elastin + microfibrils
- Elastin + microfibrils = Tropoelastin
- Collagen fibers form around tropoelastin for binding
Reticular Fibers
S: very thin | flexible | good w/ silver stain | Argyrophilic | PAS (extra carb content) | Collagen Type III fibrils
Location: lymphatic | spleen | stretching organs
Reticular Fibers Synthesis
Collagen Type III forms fibrils (thinner than Type I)
Mesenchyme
Embryonic CT (of CT Proper)
S: Mesenchymal cells | NO visible fibers | mainly ground substance
F: give rise to other CT (adult CT | blood/vessels)
Mucous Connective Tissue (gelatinous)
S: distinct fibers | loose framework | fibroblasts + collagen | undefined shape
F: prevents kinking
Location: umbilical cord | ruminant stomach
Loose (Areolar) Connective Tissue
Adult CT (CT Proper)
Most common CT in adults
S: many cells | all fiber types
F: controls spread of infection + supportive function
Reticular Connective Tissue
Type of Loose CT (CT Proper)
S: reticular fibers | loose CT | not densely filled | network (web)
L: lymphatic | bone marrow
White Adipose Tissue
Type of Adult CT (of CT Proper)
S: many adipocytes | highly vascular | unilocular
F: lipid metabolism/storage | protection | heat insulation
Brown Adipose Tissue
Type of Adult CT (of CT Proper)
S: many adipocytes | highly vascular | multilocular | “foamy” cyto | central nucleus | brown (mitochondria)
F: heat production (via lipid oxidation)
L: hibernating animals | axilla | shoulder girdle
Dense Regular Collagenous Connective Tissue
S: tensile strength | many fibers | parallel fibers | dense | Collagen Type I
L: tendons | ligaments | joint capsule
Dense Irregular Collagenous Connective Tissue
Type of Adult CT (of CT Proper)
S: tensile strength | many fibers | irregular fibers
L: dermis | sclera | organ capsules (kidney) | joint capsules
Elastic Connective Tissue
Type of Dense CT (of Adult CT & CT Proper)
S: many fibers | regular fibers | coarse fibers + loose CT between
L: nuchal ligament | ligamenta flava (neck/vert) | grazing animals (for head down w/o work)
Cartilage Characteristics
Supportive | low friction | weight-supporting
Derived from mesenchyme / mesoderm
Cartilage Elements
Chondrocytes / Chondroblasts
Matrix (interstitium)
Chondrocytes / Chondroblasts
Cartilage cells
Chondrocyte = blast enclosed in lacuna
F: secrete matrix | produce collagen fibrils & ground substance
Matrix (Interstitium)
Fibers in firm ground substance
S: Avascular
F: Importance in diffusion
Types of Cartilage
Hyaline cartilage
Elastic cartilage
Fibrocartilage
Hyaline Cartilage
Location: synovial joint | respiratory | epiphyseal plate | embryonic skeleton | repair of fractured bone
Structure: Uniform | basophilic | hyaluronic acid chains | lacuna + chondrocytes
Histogenesis of Hyaline Cartilage
Mesenchyme –> chondroblast
Chondroblast secrete: ground substance + collagen type II fibrils
Secrete matrix –> lacunae (compartments)
Territorial vs Interterritorial Matrix
Regions of matrix in Hyaline Cartilage
Territorial: nearest lacuna | pericellular | basophilic (since newer)
Interterritorial: further from lacuna | more collagen fibrils (“older”)
Interstitial vs Appositional Growth
Interstitial: slow/continuous cartilage growth from within
increase in length
Appositional: faster growth | require perichondrium (fibrous CT around cartilage) | adds outer layers | increase thickness
Elastic Cartilage
=Hyaline cartilage + Elastic fibers
S: More flexible than hyaline | collagen type II fibrils | ground substance
Location: ear pinna | auditory tube
Fibrocartilage
S: mixed unit | no perichondrium–>scar tissue | collagen type I fibers | fibrocytes in lacunae
Location: ligament/tendon –> bone | cardiac skeleton (dog) | menisci
