Lecture Exam 3 Flashcards
Functions of bone
- Structure and support
- Protection
- Stores minerals (calcium)
- Important for blood cell development
What forms of calcium are important for making bone?
- Calcium phosphate
2. Calcium hydroxide
Hydroxyapatite
Calcium phosphate and calcium hydroxide formed together; a crystal that makes bones hard
2/3 of bone is made up of what
Calcium phosphate
1/3 of bone is made up of what
Collagen, which gives out bones some flexibility
Rickets
A disease of calcium deficiency that causes bones to bend, especially in legs
What is the importance of vitamin D
It helps us absorb calcium
Osteogenesis Imperfecta
A disease of collagen deficiency, causes brittle bones
Diaphysis
The shaft of a long bone
Epiphysis
The end of the shaft
Metaphysis
Where bones grow longer; where the diaphysis connects to the epiphysis
Types of bones that make up a long bone
- Compact bone
2. Spongy bone
Compact bone
Dense, solid bone; extremely strong in one plane; surrounds the diaphysis for protection
Medullary cavity
The hollow space of the diaphysis; Bone marrow
Osteon
Makes up compact bone; the entire circular structure
Central canal
In compact bone; has blood vessels (usually an artery and a vein); brings in nutrients and takes away waste products
Concentric lamellae
In compact bone; each circle that makes up an osteon
Osteocyte
In compact bone; The dark spots in a concentric lamellae that makes bone until it traps itself in a lacuna
Lacuna
Compact bone; Where the osteocytes trap themselves
Canaliculi
Compact bone; Tunnels that connects all of the osteocytes together; made by osteocytes to get nutrients from the central canal
Interstitial lamellae
Compact bone; Bone tissue that fills in the gaps between the osteons; made from old osteons that have been recycled
Circumferential lamellae
Compact bone; Allows bones to grow in diameter; surrounds an osteon completely; created from stress on the bone and makes the bone bigger
Periosteum
Compact bone; A layer of connective tissue that surrounds the bone; allows tissue to connect to bone
Perforating fibers
Compact bone; Collagen fibers that embeds in the bone and prevents the periosteum from pulling away when the muscles pull on it; originates in periosteum
Spongy bone
Surrounds the epiphyses; strong in multiple planes
Trabeculae
Fibers that make the web-like structure of the osteons in spongy bone
Types of cells in bones
- Osteoprogenitor cells
- Osteoblasts
- Osterocyte
- Osteoclast
Osteoprogenitor cell
Comes from mesenchymal stem cell; stem cell that can only become bone cells; divide and helps make and repair bone
Mesenchymal stem cell
A stem cell that has the ability to form many types of cells
Osteoblasts
Osteoprogenitor cells mature/form into this; bone forming cell
How osteoblasts create bone
- Osteoblasts create osteoid
2. Osteoblasts raise calcium above its solubility limit
Osteoid
The foundation of bone; the organic part of bone; this is where collagen is found
Solubility limit
When sugar is continually added to water and won’t dissolve anymore; calcium does this and crystalizes, making bones strong and hard
When is a osteoblast called an osteocyte
Once an osteoblast makes all the calcium that is can and is trapped in a lacuna
FOP
Osteocytes are overactive and osteoblasts are formed in tissue where they should not be
Osteoclasts
Formed from a macrophage; this cell type degrades/breaks down bone
How do osteoclasts and osteoblasts work
They work together in equilibrium
When does bone growth begin
At 6 weeks post fertilization
How do bones begin
They begin as cartilage until osstification
Osstification
The process of replacing other tissues with bone
Two forms of osstification:
- Endochondral osstification
2. Intramembranous osstification
Endochondral osstification
The formation of long bones
Intramembranous osstification
The formation of non long bones
Chondrocytes
Cells that make hyaline cartilage
Cartilage is what kind of tissue
Avascular tissue
Why is cartilage avascular?
Because chondrocytes make anti-angiogenesis factor
Anti-angiogenesis factor
Made by chondrocytes that prevents blood vessel formation
Hypertrophy
When chondrocytes swell and get large; shortly after undergoing hypertrophy the chondrocytes die which enables blood vessel growth
Where does bone formation begin?
At the diaphysis (shaft)
What happens once blood vessels grow
Nutients and bone cells (mesenchymal stem cells that become osteoblasts and macrophages that become osteoclasts) begin to be delivered into the center of the cartilage
How is cartilage turned into bone?
- Osteoblasts turn all of the cartilage into bone
2. Osteoclasts carve out the medulla to make bone hollow
Primary osstification center
The place in the diaphysis that is osstified first
Secondary ostification center
The place in the epiphysis that is osstified after the primary
What is different about the secondary osstification center from the primary osstification center?
Not all of the cartilage is osstified and turned into bone
Examples of cartilage that is not turned into bone
- Articular cartilage
2. Epiphysis cartilage
Articular cartilage
Cartilage that surrounds the end of the epiphysis; this reduces friction between bones
Epiphyseal cartilage
This is between the diaphysis and the epiphysis; this is the “growth plate” where bones can grow longer; once it is gone, the bone cannot get any longer
How is intramembranous ossification different from endochondral ossification?
Flat bones do not start off as cartilage
How are flat bones made?
Osteocytes make bone, then osteoclasts carve out the bone and make it into a specific shape
Types of post-developmental bone growth
- Appositional growth
2. Epiphyseal growth
Appositional growth
Increase in bone diameter
Epiphyseal growth
Increase in bone length
Where does appositional growth happen and how does it happen?
At the circumferential lamellae, osteoblasts add more circumferential lamellae layers
What is different about appositional growth and epiphyseal growth?
Appositional growth occurs throughout your lifetime, epiphyseal growth begins at birth and lasts throughout the end of puberty
What causes an increase in appositional growth
Stress on a bone
What happens on the lower part (B) of the epiphyseal cartilage?
Osteoblast turns cartilage into bone
What happens on the upper part (A) of the epiphyseal cartilage?
Chondrocytes make new cartilage, as fast (almost) as the osteocytes are making bone
Hormones that are important during puberty
- Testosterone
- Estrogen
- Growth hormone (HGH)