Intro to Skeletal System Flashcards
What percentage of bone is inorganic/calcified?
70%
What percentage of bone is organic/collagen?
30%
Bone is anisotropic. What does this mean?
That bone is stronger in some orientations than others – it responds better to compression than shear stress.
What is an osteocyte?
A mature bone cell that maintains the protein & mineral contents within the matrix.
What does an osteoblast do?
It secretes osteoid, which creates cartilagenic bone.
What does an osteoclast do?
It secretes acid to dissolve & remove bony matrix.
What is the role of osteoprogenitor cells?
They produce osteoblasts, which is important for fracture repair.
What is inside of the open space in spongy bone?
Marrow
Where is compact bone most concentrated?
At the periphery/on the outside edges of the bone.
Where are red and yellow marrow contained?
Within the medullary cavity
Where is the periosteum and endosteum?
Peri = outside, end = inside
When you get a shin splint, which part of the bone is being pulled?
The periosteum
What is another name for an osteon and what shape is it?
A Haversian system, it’s concentric/circular
What is at the centre of an osteon?
Blood vessel canal
How does intramembranous (dermal) ossification occur? (4 steps)
- Mesenchymal/stem cells -> osteoblasts -> ossification center
- Osteoblasts -> osteocytes -> calcify bone
- Blood vessel feeds developing bone
- Adult bone develops into spongy and compact layers.
How does endochrondal ossification occur? (4 steps)
- Primary ossification center develops in the diaphysis
- Medullary cavity forms as space for the marrow
- Secondary ossification centers develop on the proximal and distal ends (epiphyses)
- Growth plates (metaphyses) form and then calcify around age 25
Why do some doctors mistakenly diagnose fractures in children?
Because their bones have not fully calcified, and cartilage cannot be seen on an x-ray.
During growth, bone is resorbed on the inside by __________ & deposited on the outside by __________
Resorbed by osteoclasts, deposited by osteoblasts
From strongest to weakest, rank the three types of stress on bones.
- Compressive
- Tensive
- Shear
What are the 4 steps of bone fracture repair?
- Extensive bleeding, forming a large blood clot.
- Internal callus unites the inner edges and external callus stabilizes the outer edges
- Cartilage is replaced by bone, fragments are dissolved and the broken ends are united by spongy bone.
- Swelling marks the location, but is remodeled over time.
What is osteoporosis?
Bone death, where spongy bone becomes porous & does not react as well to stress. Starts to bend and snaps more easily than healthy bone.
What are the 5 bone shapes?
Long (ie. limbs) flat (ie. skull) short (ie. wrist) pneumatized (ie. nose cavity) irregular (ie. vertebra)
What are the three joint types?
Fibrous, Cartilaginous and Synovial
What is the most stable joint type and what is an example of it?
Fibrous (ie. skull sutures)
What is the difference between primary and secondary cartilaginous joints?
Primary joints disappear with age (ie. growth plates) and converted into bone.
Secondary joints persist throughout the lifetime.
What is a synchondrosis?
Cartilage that is converted into bone with age.
What is a symphysis?
Permanent cartilaginous union between bones.
What is the name of the mobile joint between two long bones?
Synovial, the most common type.
What is the great thing about synovial fluid?
It prevents friction extremely well, better than motor oil.
What is the difference between a hinge joint and a ball-and-socket joint?
Hinge joints only move in one direction (flexion and extension), whereas ball-and-socket joints are much more mobile.
