Flashcards in Lecture 9- Bone Deck (45)
What type of tissue is bone?
What are the components of bone?
Cells and Extracellular Matrix (Bone Matrix)
What cells make up bone?
4. Bone lining Cells
5. Osteoprogenitor Cells
What makes up Bone Matrix?
2. Ground Substance
What is general fibrous structure of bone and why is it like that?
Fibers are aligned parallel but are oriented in different directions.
What gives bone its strength?
A calcified bone matrix
What cells help "maintain" the bone matrix?
How does the osteocyte gets its nutrients and get rid of waste?
What happens in the canaliculi?
Exchange of nutrients and waste products that travel down cell to cell of dendritic processes of osteocytes
What structure aids w/ transfer of nutrients from one osteocyte to another?
2 General Types of Bone Structure
1. Compact Bone
2. Cancellous Bone (AKA spongy or trabecular bone)
Is compact bone and cancellous bone made of the same material?
Yes. Both Lamellar bone. Organized differently.
Where do osteoblasts come from?
Bone lining cells or osteoprogenitor cells.
Steps of the bone remodeling cycle (3).
1. Osteoclast (apoptosis)
2. Osteoblast Secretes bone matrix (osteoid - unmineralized bone)
Where does bone remodeling occur?
1. On the surface of bone
2. In the middle of bone
How does bone modeling occur in the middle of bone?
1. Clasts come through blood vessel, start working to make a connecting canal
2. Blasts stay on surface (bone lining cells) and fill in canal with bone (surround blood vessels)
3. Cytes sit in lacuna and maintain matrix and stim remodeling cycle from stress
What is osteoporosis?
1. Decreased bone mass per unit volume of anatomical bone.
2. After 35, clast > blast
Biphosphonates can help limit osteoporosis, but osteonecrosis may be a side effect, why?
Biphosphonates disrupt bone remodeling. When there is continual stress on the bones, they have a limited capacity for healing
Different kinds of osteogenesis (2)
1. Intramembranous Ossification
2. Endochondral Ossification
Most flat bones develop via _______ ossification.
Steps of intramembranous ossification (4)
1. Mesenchymal cells in CT membrane or sheet form clusters
2. Cluster differentiates into osteoblasts = ossification center
3. Osteoblasts secrete osteoid
4. Becomes mineralized
What is condensed mesenchyme?
Mesenchyme that is more cellular
What kind of bone is intramembranous bone?
Primary bone or Woven Bone = SPONGY
*NOT LAMELLAR BONE or secondary bone
What are trabeculae made of and how is it oriented?
What happens during the remodeling of woven bone?
Where can you find this kind of bone?
It become lamellar bone, with collagen fibers oriented in parallel.
Flat bones like in the skull.
What does endochondral ossification mean?
Cartilage that turns to bone.
Steps of endochondral ossification.
1. Mesenchymal Cells Condense during fetal development
2. Develop into chondrocytes
3. Cartilage is developed into the shape of the bone that it will form (surrounded by perichondrium)
4. Cartilage deteriorates and becomes primary ossification center (woven bone), has blood vessel of periosteal bud
5. Secondary Ossification Centers develop at the ends of the bone
Why is epiphyseal cartilage important?
It allows you to get taller
Zones of epiphyseal growth plate (5)
Zone 1 - Hyaline Cartilage (resting zone)
Zone 2 - Proliferation - making more chondrocytes
Zone 3 - Hypertrophy
Zone 4 - Calcification - osteoblasts come in and lay down bone
Zone 5 - Ossification