SKELETAL SYSTEM CARTILAGE Flashcards
What is cartilage?`
- Special form of Connective Tissue
2. Provides strength and flexibility
What is cartilage lined by?
- Perichondrium (a layer of dense connective tissue)
* Except for articular cartilage
What cells are part of cartilage?
- Consist of chondroblasts and chondrocytes
What are chondroblasts in cartilage?
- Immature cells
- Cartilage precursor cells
- Undergo 1 or 2 mitotic divisions
- Synthesize components of the extracellular matrix during the period of rapid proliferation
*Become chondrocytes as they are enclosed by the ECM that separates them from each other
What are chondrocytes in cartilage?
- Only cell type in the mature cartilage (on completion of growth)
What is extracellular matrix in cartilage?
- Known as chondroid
- Consist of organic components (fibrous protein, and ground substance) “25%”
- Consist of Water (75%)
4 NO inorganic components
What is subchondral?
Are blood vessels below cartilage
What does cartilage lack?
- Blood vessels
- Lymph vessels
- Nerves
What is the repair capacity of cartilage?
- Poor repair capacity (heals slowly when damaged)
2. Underlying (subchondral) bone and Peripheral synovial membrane repair damage cartilage by vascular tissue
How does cartilage get its nutrients?
- Diffuse through the matrix
2. Supplied by Synovial fluid; blood vessels in the perichondrium; and subcondral bone
What are the 3 types of cartilage?
- Hyaline
- Elastic
- Fibrocartilage
What is Hyaline cartilage?
- Most common type of cartilage (glassy appearance)
- Forms nearly all fetal skeleton (temporary cartilage)
- Type 2 collagen
- Basophilic matrix
- Chondrocytes arranged in groups
- Perichondrium present except in articular cartilage
Where is Hyaline cartilage found?
- Nose
- Larynx (except for the apex)
- Trachea
- Bronchi
- Coastal cartilage (prone to ossification; lined by periosteum)
*Articular ends of long bones
What are the 2 forms of hyaline cartilage?
- Epiphyseal plate
2. Articular cartilage (Does not ossify)
What is articular cartilage?
- One form of hyaline cartilage that has more collagen than other types of hyaline cartilage
- Not surrounded by perichondrium or periosteum
What is the function of Articular cartilage?
- Load distribution
2. Decrease friction
What is a tidemark in articular cartilage?
- A calcified line separating the calcified zone from the upper zone
- Represents a plane of weakness
What happens when articular cartilage is damaged?
- Known as superficial laceration
- Superficial lacerations do not heal, although some proliferation of chondrocytes may occur
- Immobilization of joints leads to atrophy of the articular cartilage
- Continuous motion is beneficial to healing
- Deep laceration- occur below the tidemark and heal with fibrocartilage
- Blunt trauma causes osteoarthritis
What is Elastic Cartilage?
- Contains type 2 collagen and elastic fibers
- Branch extensively in all directions
- Gives cartilage the ability to be deform and spring back into shape immediately
- Perichondrium present
Where is elastic cartilage found?
- Places where specific shape in needed for maintenance and function
- Pinna of ear
- Auditory canal
- Pharyngotympanic tube
- Larynx (Epiglottis, corniculate, cuneiform, apex)
What is fibrocartilage?
- A combination of dense collagenous fibers and chondrocytes
- Lacks perichondrium
- Never occurs alone
- Merges with adjacent tissue
- Type 1 collagen
Where is fibrocartilage found?
- Places that require resistance to compression and shear force
- Symphysis pubis
- Menisci
- Glenoid
- Acetabular labra
- Temporomandibular
- Stenoclavicular
- Sacrococcygeal joints
- Intervertebral disk
What is the extracellular matrix in fibrocartilage?
- Ground substance (minimal)
2. Fibrous component (Type 1 collagen; parallel fascicles)
What is Annulus fibrosus in IV disc?
- Fibrocartilage near nucleus pulposus
- Dense CT along its periphery
- The outer part of a IV disc
What is Nucleus pulposus
- Scattered rounded cells in a viscous rich Hyaluronic acid
* Nucleus pulposus is the inner core of the vertebral disc
What does Thyroxine, testosterone, and somatotropin do to Hyaline Cartilage?
- Stimulates cartilage growth and matrix formation
What does Cortisone, hydrocortisone, and estradiol do to Hyaline cartilage?
- Inhibit cartilage growth and matrix formation
What does HYPOvitaminosis A do to Hyaline cartilage?
- Reduces width of epiphyseal plate
* defiencency in Vitamin A
What does HYPERvitaminosis do to Hyaline Cartilage?
- Accelerates ossificaiton of epiphyseal plate
* Excess amount of Vitamin A
What does HYPOvitaminosis C do to hyaline cartilage?
- Inhibits matrix synthesis and deforms architecture of epiphyseal plate
- Leads to scury
What does the absence of Vitamin D do to hyaline cartilage?
- Proliferation of chondrocytes is normal but matrix does not become calcified
- Results in rickets
What is perichondrium?
- Surrounds cartilage except on articular cartilage and fibrocartilage
- Consist of two layers: Outer fibrous layer and cellular (chondrogenic) layer
- Contains fibroblasts (produce collagenous fibers)
What is the outer fibrous layer in perichondrium?
- Dense irregular CT
2. Contains fibroblasts, which produce collagenous fibers
What is the cellular (chondrogenic) layer in perichondrium?
- Contains blood vessels
- Source of chondroblasts
- Less prominent after cartilage is full grown
What is the function of perichondrium?
- Appositional growth and repair of cartilage
- cartilage is permanent and is not remodeled like bone
- damaged cartilage is replace by collagenous scarring
