Lecture 5 - Cartilage and Bone Flashcards
What is Cartilage
A Specialized Connetive Tissue
What are the Three Types of Cartilage
Hyaline, Fibrocartilage, and Elastic Cartilage
Hyaline Cartilage (ECM, Chond. Arrangement, Perichondrium, Location, Function )
ECM - Collagen II
Chondrocytes are arranged in little groupings isogenous
There is a perichondrium except the articular Cartilage
Seen at location of two bones meeting.
Used for Sliding
Seen in nose, trachea, bronchi, end of ribs
Articular Cartilage
A subset of Hyaline cartilage that is seen between two bones
does not have perichondrium
Fibrocartilage (ECM, Chond. Arrangement, Perichondrium, Location, Function )
Type II with Type I collagen Chondrocyte in parallel rows no perichondrium Seen in between vertebrate and the meniscus Specialized to absorb force, cushioning
Elastic Cartilage (ECM, Chond. Arrangement, Perichondrium, Location, Function )
ECM - Type II collagen with Elastic Fibers
Chondrocytes are in little pockets of isogenous groups
Perichondrium - there is one
Locations - epiglottis, Larynx, and ear
Function - is shape and elasticity
Properties of Cartilage
Avascular - Relies on diffusion for nutrients
Lacks Sensation - No nerve system
Functions of Cartilage
Support - Bear weight at points of movement
Movement - Provide smooth surface
Framework - Seenin growth of long bones
Composition of Cartilage
Remember it is a Connective Tissue so Cells and ECM
Cells - Chondrocytes
ECM - Type II collagen (fiber), Proteoglycans, glycoproteins ( Ground Substance)
Lots of water
Perichondrium
DENSE Layer of connective tissue on outer surface (surrounding the cartilage)
Seen in all cartilage except articular and fibrocartilage
contains two layers inner cellular layer, and outer fibrous layer
The two layers of the perichondrium
Inner Cellular Layer - Gives rise to new cartilage
Outer Fibrous Layer - Connective Tissue layer. Note the blood vessels are in this layer
Chondrocytes
Cell of Cartilage Formed by Chondroblasts
that produce Chondrocytes
Chondrocytes make the ECM (collagen II, proteogylcans, glycoproteins)
Two Types of Cartilage Growth
Appositional Growth
Interstitial Growth
Appositional Growth of Cartilage
New Cartilage forms at surface of existing cartilage
Derived from inner portion of the perichondrium
Interstitial Growth of Cartilage
New Cells Form by mitosis of existing cartilage
What is an isogenous group os Cartilage
It is a cluster of chondrocytes that recently divided
This is seen Hyaline and Elastic Cartilage
Osteoarthritis
Type II collagen production inhibited
Related to age and traumo
No symptoms until the bones wear down and grind another
Articular Cartilage Disease
Herniation
A protruding into space that it should not be
Seen in the intervertibrate discs
There is a problem in fibrocartilage that weakens it and so it comes out the edges of the spinal cord. Hitting nerves for pain
Characteristics of Bone
Vascularized highly Innervated
Mineralized (so hard)
Function of Bones
Protects and Supports (skull)
Movement
Reservoir of Ca and P
Form Blood Cells
Connective Tissue of Bone is split in to two what are they
Outer Surface - Periosteum
Inner Surface - Endosteum
Periosteum
Outer Surface of the bone
Two Layer Sheath
Outer fibrous layer of dense CT
Inner Cellular layer
Endosteum
Inner Surfaces of bone
One layer around inner cavity (the bone cavity)
Contains the bone stem cells
Macroscopic Classification of Bone
Compact/Cortical Bone
Spongy/Cancellous Bone
Compact / Cortical Bone
Dense Layer surrounding outer bone
Organized osteon system
Dense in areas of stress
Spongy / Cancellous Bone
Forms network of Trebeculae in interior (thin bands of bone)
Well Vascularized and innervated
Not random organized along force and stress
It looks random though
Microscopic Classification of Bone
Primary Bone (Immature Bone) Secondary Bone (Mature, or lamellar)
Primary Bone/Immature Bone
New Bone laid down is disorganized and low mineral
Lamellar Bone
Aka Secondary bone, Mature Bone
ORganized structure that replaces primary bone
composed of concentric lamellae
is Calcified
Osteons
Structural Units of Mature Bone. A grouping of rings of lamellae
Lamellae
Osteons are formed by bone matrix that form concentrically around a central cavity
Each ring is a lamellae
Haversian Canal
Center of Lamellae
Contains the neurovascular Stuff
Interistual Lamellae
Places where osteons are degraded
Remnants of previous osteon lamellae
Outer/Inner Circumferential Lamellae
They Go around the whole shaft of the long bone
Outer Circumferential - Right below the periosteum
Inner Circumferential - Right below the endosteum
Volkmanns Canals
Connects Osteons
Blodo Vessels and nerves can connect and coordinate
Run 90 Degrees to the long axis (haversian canals)
Bone Extra Cellular Matrix Composition
Inorganic Components (calcium Phosphate is most of it) 65%
Fiber is Collagen type I
Cells are super small percent
The ground substance is glycoproteins and proteoglycans
Cells of Bone (5)
Osteoporgenitor Cells Osteoblasts Osteocytes Bone Lining Cells Osteoclasts
Osteoprogenitor Cells (function, location, structure)
Derived from mesenchymal Stem Cell Develop to Osteoblasts upon stimulus Seen in layers forming new bone location - inner periosteium layer of growing bone, and endosteum layer lining the bone cavity structure - Squamus
Osteoblasts (function, location, structure)
Function - differentiated from osteoprogenitor
- secretes type I collagen and ECM proteins forming unminerilized bone capable of division
Structure - cuboidal in single line on the surface of the bone
Location - where bone is being laid down
Osteoblasts communicate with each other through gap junctions
As osteoblasts secrete the new bone stuff they slowly get surrounded by matrix and get trapped
Osteocytes (function, location, structure)
Location - Is an osteoblast that has been surrounded by bone
Function - Maintain the matrix of the bone, Starts produce copious amounts of matrix, can respond to stimuli to help osteblasts
Structure - has long arm processes to contact osteocytes and blasts through gap junctions
- they have flattened nucleus and form shape of lacunae they lie in
Lacunae
Osteocyte spot within the lamellae circles
Canaliculi
Small canals to connect the osteocyte cells to other osteocytes and blasts
Bone Lining Cells (function, location, structure)
Derived from Osteoblasts that are not producing bone
Function - support cells for osteocytes. Regulate Calcium in and out
Location - external and internal surface of bone
Structure - Flat inactive squamous
Dormant, but maybe able to become activated
Osteoclasts (function, location, structure)
Derived from the monocyte line of RBC formation
Must be activated
Function - Bone Resorption
Structure -large and multinucleated
Location - On the surface of the bone (inner) found in Howships Lacunae (subosteoclastic compartment)
Howships Lacunae
Little compartments of bone resoprtion
Location of the osteoclasts
Two Types of Bone Formation
Intramembrous Ossification
Endochondrial Ossification
Intramembrous Ossification
Direct Differentiation from stem cell to bone
Forms the Clavical mandable type bones
Endochondrial Ossification
Uses a cartilage model template for bone formation
Forms the long bones
