Cartilage and Bone Flashcards
Where does connective tissue originate from?
The mesoderm. (paraxial)
Classification of connective tissues
Ordinary (proper) includes
- Loose/dense
- Regular/irregular
Special includes
- Cartilage
- Bone
- Blood
Most abundant protein in the human body
Collagen
Provides tensile strength
Secreted into the extracellular space
How many types of collagen
- Most common are 1, 2,3, 4, and 7
Tropocollagen
Amino acid monomer secreted by ___ and binds together to form a polymer, which is collagen.
Organization of collagen from collagen molecule to tendon unit
Collagen molecule- collagen fibril- collagen fiber- collagen fascicle- tendon unit
Fibrous collagen types
Type 1- most common. Dermis, ligaments, bone, and cornea.
Type 2- Think cartilage. Hyaline cartilage (which is articulating surfaces of bones, nose, and trachea)
Type 3- Reticular collagen. Meshwork in highly cellular organs (liver, spleen, kidney)
Collagen found in epithelial basement membranes
Type 4- 2D matrix that forms the basal lamina, mesh-like.
Type 7- Basement membrane anchoring fibrils
The 2 types of connective tissue fibers
Elastin (E) and microfibrils (M, ML)
Where do you find elastin?
Found where you want tissues to stretch, like your elbows and knees. Amorphous polymer of tropoelastin, which is similar to how collagen is produced.
Problem- Doesn’t lay down well in the extracellular matrix. Needs a scaffold for it to grow, which is composed of microfibrils.
Role of microfibrils
Structural scaffolding of elastin. Supports elastin deposition.
Fibril forming molecules
Fibrillin- scaffold for elastin deposition.
fibronectin- Helpful when closing gaping wounds.
Most common cartilage in human body
Hyaline Cartilage- can be found in the rib cage, trachea, bronchi, long bones, and joints
Costal cartilage
Hyaline cartilage of rib cage
Where is the only place that you can find hyaline cartilage without perichondrium
Joints
Where in the body can you find hyaline cartilage
Rib cage, trachea, bronchi, joints (without pericardium) and long bones
Elastic cartilage
Hyaline + elastic cartilage
Where can you find elastic cartilage
Outer ear and epiglottis
***Hyaline and elastic cartilage contain what type of collagen
2- where chrondroblasts and chondrocytes reside
Except the perichondrium has type 1 collagen (contains fibroblasts)
Fibrocartilage cartilage contains which type of collagen
Contains both fibroblasts and chondroblasts and chondrocytes together. Happy family. Therefore, there is not a perichondrium. As if the perichondrium is mixed in
Has properties of regular connective tissue and cartilage.
Allows flexibility and strength.
Hybrid between true cartilage and true connective tissue.
Contains type 1 and type 2 collagen
**The fibrous layer of the perichronidrum in hyaline and elastic cartilage specifically contains which type of collagen
Type 1
Where can you find fibrocartilage
Outer layer of intervertebral disc, called the annulus fibrosus
Ligaments
Lines inside/fills extra space of foramen lacerum, where sympathetic innervation enters. Sympathetic innervation hitches a ride with the internal common carotid that enters the carotid canal nearby.
Cell types in the bone
Osteoblasts- giveth
Osetocytes- maintenance
Osteroclasts- taketh away
Bone types
Compact (cortical)
Cancellous AKA trabecular/spongy
Periosteum. Where is it found and what layers does it have?
Outer layer of the bone.
Contains 2 layers-
1. Outer is the stratum fibrous. Type 1 collage, fibroblasts, dense irregular. Very similar in properties to fibrous tissue in perichondrium.
2. Inner is the Cambian layer (cellular) A layer of undifferentiated cells. Typically differentia
Sharpey fibers
Helps connect periosteum to connective tissues.
Extra bonding strength to prevent breakage.
Is periosteum found on bone joint?
No. Periosteum fades away and is replaced with hyaline cartilage.
4 layers of compact bone
Periosteum
- Outer circumferential lamellae
- Inner circumferential lamellae
- Concentric/circular lamellae. Form a unit called an osteon, which is the general unit of compact bone.
- Interstitial lamellae. Fills space between osteons.
basic unit of compact bone
Osteon, which is formed by concentric lamellae and filled in with interstitial lamellae
Lacuna in bone
Cavity that is in compact bone after osteocyte leaves the calcified area.
Canacliculi or canaliculus
Osteocyte cellular extensions that will leave behind a canal after calcification. These extensions will communicate with the vasculature of the bone
Center of concentric lamella/center of osteon, we find?
The central canal, which contains longitudinal vasculature
Central canals are linked via
Volkmann’s canal- transverse vascularization of arteries/veins/and lymphatics
Volkmann’s
Communicates between the central canals of osteons
Thin connective tissue that lines between compact and spongy bone.
Endosteum.
Much thinner than periosteum and contains osteoblasts and class.
Osteoclasts in spongy bone
Are able to dissolve bone to liberate Ca2+ into the body using enzymes. The area they dissolve around them creates a cavity called howship lacuna.
Howship lacuna
Cavity that is formed in spongy bone due to osteoclasts dissolving bone around itself.
Intramembraneous ossification (IO) forms which type of bone? and what is it derived from?
- Forms flat bones such as the skull, pelvis, vertebra, sternum
- Derived from mesenchymal tissue
2 types of bone development
Intramembraneous ossification- formation of flat bones. Derived from mesenchymal tissue.
Endochondral ossification- formation of long bones. Derived from hyaline cartilage.
Endochondral ossification (EO) forms which type of bone? and what is it derived from?
Forms long bones, derived from hyaline cartilage.
Spongy area in flat bones
Diploe
Primary and secondary ossification of endochondral long bones
Primary- ossification of the diaphysis (Shaft)
Secondary- ossification of the epiphysis (ends)
Layers of the growth plate
Reserve- mitosis
proliferation- very active chondrogenic cells, undergoing mitosis
maturation- cell activity decreases but cell grows in size
hypertrophy/calcification- cells can no longer grow, being to calcify.
degernation- Cells are replaced by osteogenic cells
osteogenic - true bone
Metaphysis
Transition layer between epiphysis and diaphysis. Transition from cartilage to bone.
Bone repair simple mechanism
uses a hyaline cartilage template before osteogenic cells replace it. Healed fracture leaves behind secondary bone, or callus.
Diarthroses
Freely moveable joint
Synarthroses
Immoveable joint or minimal movement. Ex: hyaline cartilage in ribs, skull sutures
Articular cartilage
Hyaline cartilage that covers the surface of bone. (Does not have a perichondrium. Do not want this cartilage to grow)
Hernitated disc
Occurs when annulus fibrosis around the nucleus pulposus ruptures. When it ruptures, the nucleus pulposus will expand to fill the space, which results in compression of the spinal cord.
Bisphosphonates
Indirectly block osteoclast activity.
Results in bone mass increase.
