Histology - Cartilage And Bone Flashcards
Elastic cartilage
- Contains type II collagen and elastic fibers
- -> More flexible
Hyaline cartilage
- Contains type II Collagen in its matrix
- Most abundant cartilage in the body
Hyaline cartilage
Location:
- The nose
- Larynx
- Anterior ends of the ribs
- Articulating surfaces of the movable joints of the body
The matrix is composed of:
- Type II collagen
- Proteoglycans
- Glycoproteins
Which is the most abundant cartilage in the body?
The hyaline cartilage
Perichondrium
- Connective tissue covering the cartilage
- Outer fibrous layer and inner cellular layer
- Vascular, and its vessles supply nutriens to the cells of the cartilage
- Perichondria are present in:
> Hyaline cartilage
> Elastic cartilage
> NOT in fibrocartilage
Inner cellular layer (see perichondrium)
Composed of:
- Mostly chondrogenic cells
Fibrocartilage
- Contains type I collagen fibers
- Resist strong tensile forces
Outer fibrous layer (see perichondrium)
Composed of:
- Type I collagen
- Fibroblast
- Blood vessles
Pericellular caspule (p. 134)
- Small region of the matrix surrounding the lacunae
- Protect the chondrocyte from mechanical stress
Connective tissue sheath covering that overlies most cartilage and has an outer fibrous layer and inner cellular layer
Perichondrium
Chondroblast + matrix =?
Chondrocytes
Osteoblast
- Synthesize the organic components of the bone matrix components, including type I collagen, proteoglycans and glycoproteins.
- Produce RANKL, osteocalcin, osteopontine, osteonectine, bone sialoprotein, and macrophage colony-stimulating factor (M-CSF)
- Basophilic cytoplasm
- Its organelle are polarized
- Alkaline phosphatase is on the CM of osteoblast.
- Osteoid separate osteoblast and osteocyte from calcified substance
ECM of cartilage
Composed of:
- GAGS
- Proteoglycans
- Collagan
- Elastic fiber
The collagen and the elastic fibers are embedded within the matrix
Chondrification
Individual mesenchymal cells retract their processes, round up, and concregate in dense masses.
Cells of bone
- Osteoprogenitor cells
- Osteoblasts
- Osteocyte
- ## OsteoclastThe first 3 belong to the same linage.
Wheras the 4th derived from monocyte precusors
Hydration shell
- The surface ions of the crystals attract H2O and from hydration shell, which permits ion exchange with the extracellular fluid
Which cartilage posses acidophilic matrix?
Fibrocartilage
Chondronectin
- Adhesive glycoprotein in the cartilage matrix
- Has binding sites for:
> Type II collagen
> Chondroitin 4-sulfate
> Chondroitin 6-sulfate
> Hyaluronic acid
> Integrins of chondroblast and chondrocyte
–> Chondronectin thus assists these cells in maintaining their contact with the fibrous and amorphous components the matrix
Which cartilage posses basophilic matrix?
Hyaline cartilage
Bone marix
- Composed of cells lying in an ECM that has become calcified
- Calcified bone mateix is composed of:
> Fibers
> Ground substance - Fibers:
> Type I collagen - Ground substance:
> Rich in proteoglycans with chondroitin sulfate and keratan sulfate side chains
> Glycoproteins that also are present:
~ Osteonectin
~ Osteocalcin
~ Osteopontin
~ Bone sialoprotein
Periosteocytic space
Space between the plasmalemma of the osteocyte and the walls of the lacunae and canaliculi
Which cells have basophilic cytoplasm?
- Macrophages
- Osteoblast
Bone matrix
- Acidophilic
- Hydroxapatite crystal
- Hydration shell
The shaft of a long bone is called……….
Diaphysis
Articular ends of a long bone is called……..
Epiphyses
Which proteins influence the devolpment of osteoblast?
- Bone morphogenic protein (BMP) family
- Transforming growth factor-B
Small cavities within the extracellular matrix which the chondrocytes occupy is called…….
Lacunae
Periosteum
- Covers the bone on its external surface, exept for the synovial joints
- Consists of:
> Outer layer of dense fibrous connective tissue
> Inner cellular layer, containing osteoprogenitor cells and osteoblasts
Where are the gap junctions found in bone?
- Between osteoblast and osteocyte.
- Between osteocyte and osteocyte.
Bone sialoprotein
- Matrix protein that also bins to integrin of the osteoblast and osteocytes
- > this make the protein related to adherence of bone cells of bone matrix
Osteopontin
- Glycoprotein
- Binds to hydroxapatite and intergrins on osteoblast and osteocyte
Osteocalcin
- Glycoprotein
- Binds to hydroxapatite
Osteoclast-stimulating factor
Activate osteoclast to resorb bone
Osteoclast have receptors for:
- Osteoclast stimulating factor
- Colony-stimulating factor-1
- Osteoprotegrin
- Calcitonin
The inorganic constitutents of bone
- Crystals of calcium hydroxapatite, composed mostly of calcium and phosphorus
- Hydroxapatite crystal [Ca10 (PO4)6 (OH)2]
- Calcium phosphate is also prensent i an amorphous form
Organic component
- Predominant organic component is collagen
–> Type I - Sulfated glycosaminoglycans:
> Chondroitin sulfate
> Keratan sulfate - Aggrecan composite
- Glycoproteins
> Osteocalcin
> Osteopontin - Sialoproteins
What happens when the parathyroid hormone (PTH) binds to the parathyroid hormone receptor on the osteoblast?
The osteoblast will secret osteoprotegrin ligands (OPGL)
Central cavity which houses the bone marrow, a hemopoietic organ
Marrow cavity
Metaphysis
- Area of transition between the epiphyseal plate and the diaphysis
- It is from THIS plate and epiphyseal plate that the bone grows in length
Epiphyseal plate of cartilage
Separates the diaphysis from each epiphysis in a person who is still growing
Howship’s lacunae
- Depression that osteoclast occupy
- Represent are of bone resorption
Two types of bone marrow:
- Red bone marrow, which blood cells are forming
- Yellow bone marrow, composed mostly of fat
Bone matrix
Intracellular calcified material, specialized connective tissue.
Canaliculi
Communication between the capillaries and osteocytes, which is a thin cylindrical space.
Endosteum
Layers of tissue containing osteogenic cells - internal surface.
Periosteum
External surface.
Osteoblasts (form bones)
Responsible for the organic components of bone matrix, type 1 collagen, proteoglycans, glycoproteins. Osteoblasts are located side by side on the surface of the bone tissue common with simple epithelium. Lacuna space - a space that appears during development.
Osteoid
New but not yet calcified matrixes.
Bone apposition
Is completed by subsequent deposition of calcium salts into new matrix. Producing a layer new layer matrix.
Osteocytes
Derives from osteoblasts lie in the lacunae situated between lamelle left of matrix. Only one osteocytes is found each lacuna. Gap junction when contacting with other cells through processes. Their death results in resorption of the cell and matrix. These are long living cells.
Osteomalacia
Mineralization is impaired (weakened or damaged)
Osteitis fibrosa cystia
Increased activity in removal of bone matrix.
Osteoclasts
Large branched motile cells, dilated (to become wider) portion of the cell body contain 5 to 50 nuclei. Derived from fusion of bone marrow.
Howship’s lacunae
Osteoclasts lie within enzymatically imprinted depressions in the matrix.
Ruffled border
The surface-facing bone matrix folded into irregular projections froms this.
Clear zone
Which surrounds the ruffled border, a cytoplasmic zone. Site of adhesion.
Bone matrix
Inorganic matter 50% of dry weight of bone matrix. Calcium and phosphate much. The organic matter is composed of collagen type 1 and ground substance and structural glycoproteins, calcifications of this is very rare. Association between minerals and collagen fibers is responsible for the hardness of the bone. Decalcification results in tendon like bone.
Hydration shell
A layer of water and ions around the crystal which facilitates exchange of ions between the crystal and the body fluids.
Osteopetrosis
Genetic disease bone resorption (remove) is defective.
Periosteum & endosteum
External and internal surfaces area covered by layers of bone forming cells and connective tissue. This is periosteum. Function as nutrition and as a repairtool for bone, or growth.
Periosteum
Outer layer of collagen fibers and fibroblasts
Sharpeye’s fibers
Bundles of periosteal collagen fibers which binds the periosteum to the bone, penetrates the bone matrix.
Osteoprogenitor cells
Fibroblasts-like cells of the inner more cellular layer, which can divide via mitosis to become osteblast.
Endosteum
Lines all internal cavities of the bone, composed of a single layer of flattened osteoprogenitor cells and some connective tissue
Primary
Immature or woven bone
Secondary
Mature or lamellar bone
Compact bone
Dense areas without cavities
Cancellous bone (spongy)
Numerous interconnecting cavities.
Epiphysis
The bulbous ends of long bones, composed of spongy bone covered by a thin layer of compact bone
Diapyphysis
The cylindrical part (growing between) almost compact bine with some spongy on the inside. Diploe and plates
Primary bone tissue
Usually temporary- can be found in sutures of the skull, tooth sockets, in some tendons irregular array of collagen fibers, lower mineral content, high ostecytes
Secondary bone tissue
Usually found in adults. Collagen fibers arraged in lamellae that are parallell like a canal. Bone surrounding the blood vessles and nerves called Haverasian system of osteon
Sementing substance
Surrounds each haversian system, mineralized matrix few collagen fibers. Haversian system, outer circumferential lamellae, inner circumferential lamellae and interstitial lamellae- in compact bone the lamellaes typical organization
Histogenesis
Bone can be formed in two way- direct mineralization of matrix or by deposition of bone matrix. In both processes the woven or primary tissue appears first. And then replaced by secondary bone.
Intermembranous ossification
Direct mineralization of matrix secreted by osteoblasts
Endochondral ossification
Deposition of bone matrix on a preexisting cartilage matrix
Remodeling
The combination of bone synthesis and removal.
Intramembranous ossification
Most of the flat bones- takes place within condesations (the process of becoming dense) of mesenchymal tissue. Thickening of long bones
Primary ossification centre
The starting point of ossification. When groups of cells differentiate into osteblasts the calcification follows which then becomes osteocytes fontanelle are connective tissue which is not yet ossified. Cranial flat bones.
Endochondral ossification
Ossification within- takes place within hyaline cartilage whose shape is like the bine future form. This type is typicall for long and short bones
Bone collar
The hollow bone cylinder that surrounds the mid portion of the hylaine cartilage. Produces by intermembranous ossification
The primary ossification center
A part of the 1st step of bone formation. Together with secondary ossification centers which appears as swelling in the diaphysis
Articular cartialge
Remains in the two regions and part of the secondary ossification center. Persists in adults through life, but not for growth in length. Epiphyseal cartilage also called epiphyseal plate connects to epiphysis to the diaphysis. Bone growth in length is almost impossible when the epiphysis is closed. Epiphyseal cartilage is divided into five zones.
Resting zone, 1
Consists of hyaline cartilage.
Proliferative zone, 2
Chondrocytes divided rapidly to form columns parallel to the axis
Hypertrophic cartilige zone, 3
Large chondrocytose and cytoplasm with glycogen. Matrix reduced to thin septa.
Calcified cartilage zone, 4
Death og chondrocytes, the thin septa calcifies.
Ossification zone, 5
Endochondral bone tissue appears. Nutrients like capillaries invades the cavities. Because the rates of the two opening events: proliferation and destruction - are approximaterly equal the epiphyseal plate does not change thickness. Instead it is displaced away from the middle of the diaphysis resulting in length growth.
