Connective Tissue And Cartilage Flashcards
This is the most varied and abundant tissue
Skeletal connective tissue
Connective tissue definition
Complex of cells and ECM that provides supporting and connecting framework for all other tissues of the body
ECM form internal …… of vertebrate body
ECM composition dictates ……..
ECM forms internal scaffold/architecture of vertebrate
ECM composition dictates mechanical properties
2 components of ECM scaffold
Fibers and ground substance
Components of fibers
Collagenous or fibrilar (30 types of collagens)
Reticular (non-fibril forming collagens)
Elastic (elastin)
Tensile strength support
Components of ground substance
Glycosaminoglycans, proteoglycans, glycoproteins
Structural glycoproteins
Fibronectin, laminin, vitronectin, tenascin, thrombospondin, entactin
Cartilage and bone are specialized …..
Connective tissues
They have a much larger ECM to cell ratio than other CTs
The ECM is secreted by
Chondrocytes
Components of individual collagen molecule
Type II collagen
Trimeric (3 polypeptide chains)
Rigid, rope-like
Positively charged (basic amino acids)
Collagen fibril composition
Composed of individual, quarter-staggered collagen molecules
Eosinophilic
Eosin is negatively charged and selectively binds to ……
Positively charged collagen molecules
What is the Supramolecular aggregate of sulfated proteoglycans
Ground substance of the cartilage ECM
3 GAGs in the ground substance of ECM
Chondroitin sulfate and keratan sulfate and hyaluronic acid backbone
Describe GAGs charge and its effect
GAGs are negatively charged due to the sulfate group and repeal each other, so they are spread out throughout the substance of the ECM
What does the negative charge of GAGs do as far as staining and hydration
GAGs are hydrophilic, basophilic, ANS metachromatic
Explain metachromatic GAGs
Because of the negative charge of GAGs, when stained, the collagen changes the color of the stain
Function of type 2 collagen in cartilage ECM
Provides rigid structural support and tensile strength
Function of PG and GAG aggregates in cartilage ECM
Hydration
Hydrated sponge concept
Cartilage can withstand great compressive forces due to stabilizing collagen matrix and ability of PG aggregates to release water and allow the matrix to compress/expand
When cartilage is compressed, PG/GAGs are
Stressed because they are closer together
Molecular sieve concept
Nutrient and gas exchange occurs via ECM and perichondrial blood vessels and ECM selectively sequesters various molecules
Is hyaline cartilage mineralized
No
4 steps of chondrogenesis
Mesenchymal condensation
Chondroblasts
Chondrocytes
isogenic groups
Mesenchymal condensation
First step of chondrogenesis
Central cells become chondroblasts
Peripheral cells become two-layered perichondrium
Chondroblasts in chondrogenesis
Divide and secrete ECM
Distance between neighboring cells increase
Chondrocytes in chondrogenesis
Cells surrounded entirely by ECM
Isogenic groups in chondrogenesis
As cells divide, daughter cells remain in close proximity, forming chondrocyte clusters
Space/nest occupied by chondrocytes
Lacunae
Mesenchyme definition
Undifferentiated cells that eventually make up connective tissue
The inner perichondrial layer is made of
Mesenchymal cells
This matrix is eosinophilic
Interterritorial matrix
2 mechanisms of cartilage growth
Apositional and interstitial
Apositional cartilage growth
Involves differentiation of chondroprogenitors (mesenchyme) and Chondroblasts on the inner surface of the perichondrium into chondrocytes
Interstitial cartilage growth
Involves division of pre-existing chondrocytes within a cartilage matrix, giving rise to Isogenous groups
3 cartilage types
Hyaline, elastic, fibrocartilage
Hyaline cartilage: functions
Function: structural support, rapid growth, ability to withstand compression; serves as a temporary skeleton during embryogenesis
What cartilage is in fetal skeletons
Hyaline cartilage
What type of cartilage is found in adults in respiratory passages like the laryngeal, trachea and bronchial cartilage
Hyaline cartilage
What type of cartilage is found in adults in the cushioning of joints such as articular and costal cartilages
Hyaline cartilage
What type of collagen is hyaline cartilage
Type 2
What is elastic cartilage composed of
Type two collagen and elastin
Functions of elastic cartilage
Flexible support, ability to withstand deformation
Locations of elastic cartilage
External ear, auditory tubes, epiglottis, larynx cartilages
What is fibrocartilage composed of
Type 1 and type 2 collagen
HYBRID
Functions of fibrocartilage
Attachment to bone, restricted mobility under great mechanical stress
Locations of fibrocartilage
Annulus fibrosus of intervertebral disk, pubic symphysis, bone-ligament junctions
Fibrocartilage is always found in conjunction with
Dense connective tissue
Hyaline cartilage serves as a temporary skeleton during embryogenesis and then is gradually replaces by trabecular bone and marrow in what process?
Endochondral ossification
Endochondral ossification defines all skeletal elements where …… will occur
Hematopoiesis