Cartilage Flashcards
_______________________ is characterized by an extracelullar matrix enriched with macromolecules that interact with collagen and elastic fibers
Cartilage
What two macromolecules characterize the extracellular matrix of cartilage?
Glycosaminoglycans
Proteoglycans
What leads to the three different types of cartilage?
Variations in the composition of glycosaminoglycans and proteoglycans in the extracellular matrix
__________________ cartilage is located between the tips of ribs and bones of sternum; covering bone surfaces at synovial joints; surrounding larynx, trachaea, and bronchi; and forms part of the nasal septum
Hyaline cartilage
The function of this cartilage is to provide stiff but somewhat flexible support and to reduce friction between bony surfaces
Hyaline cartilage
_________________ cartilage can be found in the auricle of the external ear; epiglottis; auditory tube; and cuneiform cartilages of the larynx
Elastic cartilage
The function of this cartilage is to provide support but to tolerate distortion without damage
Elastic cartilage
______________________ cartilage is located in the pads within knee joints; between pubic bones of the pelvis; and intervertebral discs
Fibrous cartilage
The function of this cartilage is to resist compression, to prevent bone-to-bone contact, and to limit relative movement
Fibrous cartilage
Cartilage consists of cells called _________________
Chondrocytes
Chondrocytes synthesize and secrete the ECM and the cells themselves are located in matrix cavities called _________________
Lacunae
Because collagen and elastin are flexible, the firm gel-like consistency of cartilage depends on electrostatic bonds between collagen fibers and the _________________ side chains of matrix _____________
Glycosaminoglycan
Proteoglycans
How are chondrocytes nourished?
By diffusion from capillaries in the surrounding connective tissue (perichondrium)
Is cartilage vascular?
No; all cartilage lack vascular supplies
Chondrocytes are nourished by diffusion from capillaries in surrounding connective tissue called _________________________
Perichondrium
Chondrocytes have ____________ (low or high) metabolic activity
Low
Does cartilage have nerves?
No
As a result of different functional requirements, how many forms of cartilage have evolved?
Three
In the matrix of _______________ cartilage, the most common form, type II collagen is the principal collagen type
Hyaline
The more pliable and distensible _______________ cartilage possesses, in addition to collagen type II, an abundance of ______________ fibers within its matrix.
Elastic
Elastic
_________________ present in regions of the body subjected to pulling forces, is characterized by a matrix containing a dense network of coarse type I collagen fibers
Fibrocartilage
What type of collagen makes up hyaline cartilage?
Type II
What type of collagen makes up elastic collagen?
Type II
What type of collagen makes up fibrocartilage?
Type I
What type of cartilage is found in the epiphyseal plate, which is responsible for the longitudinal growth of bone?
Hyaline cartilage
What color does hyaline cartilage take on when fresh?
Bluish-white and translucent
Where is hyaline cartilage located in the embryo?
The skeleton (temporary)
40% of the dry weight of _______________ cartilage consists of type __________ collagen (with small amounts of types VI and IX collagen) embedded in a firm, hydrated gel of proteoglycans and structural glycoproteins
Hyaline cartilage
Type II
Why are collagen fibers indiscernible in hyaline cartilage preparations?
The collagen is in the form of fibrils that have submicroscopic dimensions, and the refractive index of the fibrils is almost the same as that of the surrounding substances
Hyaline cartilage matrix is generally _________________ due to the high concentration of sulfated glycosaminoglycans
Basophilic
The area immediately surrounding each chondrocyte in the extracellular matrix is richer in __________________ and poorer in _______________; these areas comprise the ____________________ and usually stain differently from the rest of the matrix
Glycosaminoglycans
Collagen
Territorial matrix
________________________ is the most abundant proteoglycan of hyaline cartilage
Aggrecan
____________________ specifically mediates the attachment of chondrocytes to type II collagen
Chondronectin
________________ connects type II collage fibrils together, forming a network
Aggrecan
_____________________ function to synthesize collagens and the other matrix molecules
Chondrocytes
In hyaline cartilage, young chondrocytes can be found where?
At the periphery
What do young chondrocytes look like in hyaline cartilage?
Elliptical with their long axes parallel to the surface
As chondrocytes move deeper into the matrix, how does their appearance change?
They get rounder and may appear in groups of up to eight cells originating from mitotic divisions of a single chondrocyte called isogenous aggregates
________________________________ are groups of up to eight cells originating from mitotic divisions of a single chondrocyte
Isogenous aggregates
What happens to chondrocytes in hyaline cartilage as the matrix is produced?
Cells in isogenous aggregates are moved apart and occupy separate lacunae
_______________________ is a sheath of dense CT that surrounds cartilage in most places and consists largely of collagen type ___ fibers and contains numerous fibroblasts
Perichondrium
Type I collagen
What forms the interface between cartilage and tissue supported by cartilage?
The perichondrium
What type of cartilage lacks perichondrium?
Articular cartilage, which covers the ends of bones
How is articular cartilage sustained?
Diffusion of oxygen and nutrients from synovial fluid
Although very similar (visually) to hyaline cartilage, __________________ cartilage contains an abundant network of fine elastic fibers in addition to collagen type II fibrils and is frequently found to be gradually continuous with hyaline cartilage
Elastic
Does elastic cartilage possess a perichondrium?
Yes
Where can you find elastic cartilage?
Auricle of the ear, the walls of the external auditory canals, the auditory tubes, the epiglottis, the cuneform cartilage in the larynx
____________________ is an intermediate between dense connective tissue and hyaline cartilage
Fibrocartilage
Where can you find fibrocartilage?
Intervertebral discus
Certain ligaments
Pubic symphysis
How are chondrocytes arranged in fibrocartilage?
Chondrocytes in fibrocartilage are arranged axially in long rows separated by coarse collage type I fibers and less proteoglycans
Because it is richer in collagen type I, fibrocartilage matrix appears more _____________________
Acidophilic
What type of collagen makes up fibrocartilage?
Type I
This cartilage contains dense collagen fibers that form either irregular or parallel bundles between the axial aggregates of chondrocytes, the general orientation of which depends on the stresses placed upon it
Fibrocartilage
How do collagen bundles align themselves in fibrocartilage?
Parallel to the stresses
Does fibrocartilage have a distinct perichondrium?
No
What are the two major histological components of intervertebral discs?
Peripheral annulus fibrosus
Central nucelus pulposus
In intervertebral discus, the peripheral _______________________ is rich in bundles of type I collagen and the central ___________________ contains a gel-like matrix rich in hyaluronic acid
Annulus fibrosus
Nucleus pulposus
____________________________ act as lubricated cushions and shcok absorbers, preventing adjacent vertebrae from being damaged by abrasive forces or impact during movement of the spinal column
Intervertebral discs
All cartilage forms from embryonic mesenchyme via ___________________________
Chondrogenesis
What’s the difference between a chondroblast and chondrocyte?
A chondroblast is a cell during proliferation; a chondrocyte is a cell after proliferation
There are four major stages of embryonic cartilage formation. What are they?
Mesenchymal precursor
Chondroblasts formed via mitosis and cell differentiation
Separation and formation of the extracellular matrix
Formation of isogenous aggregates in the territorial matrix
Further growth of cartilage is attributable to two processes. What are they?
Interstitial growth
Appositional growth
_________________________ growth results from the mitotic division of pre-existing chondrocytes
Interstitial growth
___________________ grwoth results from the differentiation of perichondrial cells
Appositional growth
What contributes greatly to the growth of cartilage?
Matrix synthesis
What type of growth lays the initial foundation for cartilage growth?
Interstitial
Which of the two types of cartilage growth is less important postnatally?
Interstitial growth
___________________________ occurs during the early phases of cartilage formation and increases tissue mass by expanding the cartilage matrix from within; it occurs in the epiphyseal plates of long bones and within articular carilage
Interstitial grwoth
What type of growth occurs in the epiphyseal plates of long bones and within articular cartilage?
Interstitital growth
__________________ growth increases cartilage girth
Appositional growth
In _______________________, chondroblasts differentiate in the inner layers of the ________________________ where they proliferate and become chondrocytes; once they have surrounded themselves with cartilaginous matrix, they are incorporated into existing cartilage
Appositional growth
Perichondrium
Except in young children, damaged cartilage undergoes slow and often incomplete ______________________________
Regeneration
In extensively damaged areas, and occassionally in small areas, the perichondrium produces a _____________ of ______________________ instead of forming new cartilage
Scar
Dense connective tissue
The poor regenerative capacity of cartilage is due in part to its _______________________
Avascularity
