FINAL: Skeletal System Function & Histology Flashcards
What is the skeletal system
A dynamic system of connective tissue
Balance between production and remodeling
What are the functions of bones
Support
Protection
Movement
Electrolytes and Acid/Base balance
Blood cell differentiation (Hematopoiesis)
How many bones are humans born with
Over 300
How many bones do adults have
206
Sesamoid bone
Small bones
Embedded within tendon where is passes over a joint
Ex: patella
Wormian bones
Extra irregularly shaped bone pieces that occur within a suture in the cranium
What part of the long bone is this
Diaphysis (shaft)
What part of the long bone is this
Epiphysis (end of long bone)
Top - proximal epiphysis
Bottom - distal epiphysis
What part of the long bone is this
Metaphysis (growth plate region)
What part of the long bone is this
Medullary cavity (filled with yellow bone marrow)
What part of the long bone is this
Endosteum (inside)
- connective tissue lining medullary cavity
- contains osteogenic (bone-forming) cells
What part of the long bone is this
Periosteum (outside)
- connective tissue covering bone but not the cartilage
- osteogenic (bone-forming) cells and blood vessels that nourish or help with repairs
What part of the long bone is this
Articular cartilage
- covers joint to reduce friction & absorb shock
What are the two types of bone marrow
Red marrow and yellow marrow
What is red marrow
Found at epiphysis of long bones & spongy bone
Site for hematopoiesis (blood cell formation)
What is yellow marrow
Found within the medullary cavity
Stores fat
What are the types of tissue that bones are composed of
Cartilage
Osseous tissue
Epithelium
Nerve
Blood forming tissue
Adipose
Dense connective tissue
What is osseous tissue
Connective tissue normally called “bone”
What are the 3 basic components of connective tissue
Cells
Fibers
Ground substance
What makes up the matrix of connective tissue
50% ground substance
25% collagen fibers
25% water
What does osseous tissue consist of
Bone cells with a mineralized matrix
What are osteoprogenitor (osteogenic) cells
- stem cells
- divide to replace themselves or to produce osteoblasts and osteocytes
- found in periosteum, endosteum
What are osteoblasts
- secrete unmineralized bone matrix (osteoid)
- some mature into osteocytes
What are osteoids
Collagen, calcium-binding proteins
What are osteocytes
- mature bone cells
- help maintain surrounding matrix
- act as stress or strain sensors
- communicate with other bone cells to regulate bone growth and resorption
What are osteoclasts
- cells of matrix destruction
- derived from the same stem cells that become white blood cells
- large, multinucleate cells
- responsible for bone resporption (destruction)
What does the osteon consist of
Concentric layers of bone matrix called lamellae surrounding a central canal (Haversian canal)
What is the red arrow pointing to
The volkmann’s canal
- how Haversian canals are connected
- network of blood vessels
Where are osteocytes located
Small pockets called lacunae
What are the small channels that allow osteocytes to communicate with one another and receive nutrients
Canaliculi
What is this red line pointing to on the osteon
Canaliculi
What is this component of an osteon
Lamallae
What is this component of an osteon
Haversian canal
What is this component of an osteon
Lacunae with osteocytes inside
What is the purpose of the harness of the matrix
To provide resistance to diffusion
What happens to osteoblasts producing osteoid/matrix
They become trapped and differentiate into osteocytes
Are there osteon in spongy bone
No true osteons in spongy bone
What is this part of spongy bone
Trabeculae
