Intro to Skeletal System Flashcards
What are the 5 functional roles of the skeletal system?
- Support of body
- Protection of internal organs
- Levers for skeletal muscles to attach
- Production of blood cells through bone marrow
- Storage of minerals
What is the first characteristic of bone?
Bone is a composite material
70% inorganic calcium phosphate crystals- strong, inflexible, resist compressive stress
30% organic collagen fibres- tough, flexible, resist stretching, bending, twisting stresses
What is the second property of bone?
Bone remodels under the influence of forces
What is the third property of bone?
Bone is anisotropic- differing hardness and strength properties depending on its orientation/ plane
What are the 4 types of bone cells?
Osteoprogenitors, osteoclasts, osteocytes, osteoblasts
What are osteoprogenitors?
Stem cells found in outer/inner layers of bone, can differentiate into more specialized bone cells and have important role in fracture repair (make osteoblasts)
What are osteoblasts?
Bone cells derived from osteoprogenitor cells, secrete collagenous material called osteoid that will later mineralize
Bone producing
What are osteocytes?
Osteoblasts that become trapped in hard, bony, tissue
Mature bone cells that monitor and maintain protein and mineral contents of the bony matrix
What are osteoclasts?
Large, multinucleated bone cells derived from precursor blood cells, secrete acids that erode the bony matrix for release of amino acids and minerals in body fluids
Bone eating
What are the two different types of bones?
Spongy bone: open network of struts and plates, mostly interior
Compact bone: relatively dense and solid, mostly exterior
What is the difference between the periosteum and the endosteum?
Periosteum- membrane on exterior bone covering compact bone, fibrous tissue with one layer of osteoblasts
Endosteum- membrane covering interior bone on the spongy bone, fibrous tissue with one layer of osteoblasts
What is the medullary cavity?
Open space inside the compact bone and filled with spongy bone. It contains yellow marrow (adipocytes) and red marrow (immature and mature red and white blood cell)
What is the osteon?
Also known as the Haversian system
Basic functional unit of mature compact bone
Osteocytes organize into concentric layers around a central canal containing blood vessels supply the osteon
What is lamellar bone?
Bones made of plates that are organized into circles as you go deeper and surrounded by interstitial lamellae between in the spaces of the concentric plates
What is the first method of bone growth and what type of bone does this make?
Intramembranous (dermal) ossification.
1. Aggregation of osteoblasts forming an ossification center
2. Osteoblasts become osteoclasts
3. Developing bone grows outwards with blood vessels feeding it
4. Adult bone with spongy and compact bone
Typical for skull bones and clavicle
What is the second method of bone growth and what type of bone does this make?
Mesenchymal cells become chondroblasts the deposited which then die and become scaffold for osteoblasts to become ossification center
Primary ossification center (diaphysis in shaft)
Secondary ossification center (epiphyses at each end)
Growth plates (metaphysis remain cartilaginous and can add bone length and therefore height)
Typical of limb bones
What is the process of development and growth of bone?
The balance between osteoblast and osteoclast activity crucial in growth.
Bone is resorbed by osteoclasts, takes excess bone away to retain diameter
Bone deposited by osteoblasts
Helps increase width of shaft but keep thickness of cortical shaft the same
What are the three stresses that can be applied to bone and which are the worst?
Compression (highest threshold)
Tension (next highest)
Shear (lowest threshold)
How is bone remodeled and repaired?
Immediately after fracture large blot clot forms (hematoma)
Internal callus forms as spongy bone unites inner edges
External cartilage of callus stabilizes outer edges
Cartilage of external callus replaced by bone, fragments of bone and areas closest to break removed and replaced
Swelling initially marks location of the fracture, overtime the region is remodeled and little evidence remains
What happens to bone as you age?
You lose bone mass, and the stress:strain ratio decreases, as it takes less stress to get a large amount of strain (osteoporosis) and you lose organic and inorganic matter
What type of bones are in the skull?
Flat bon, with an external table and internal table as well as a diploe (spongy bone)
Like the parietal bone
What are pneumatized bones?
Bones with air filled spaces such as the ethmoid bone between the eyes
What are irregular bones?
Such as the vertebra, oddly shaped bones
Where are short bones found?
In the hands such as the carpal bones
