Ch. 6 - Bone Tissue Flashcards
What is the main function of the skeletal system?
support and protection of the body
What are 5 functions of bones?
- support and protection of soft tissues
- attachment site for muscles, making movement possible
- storage of minerals (Ca, PO4)
- blood cell production in red bone marrow
- triglyceride storage in yellow bone marrow
What do long bones consist of?
Diaphysis (shaft) Epiphysis (ends) Metaphysis (includes plate, where shaft grows) Articular cartilage Periosteum Endosteum Medullary cavity
What is the articular cartilage?
thin layer of hyaline C that absorbs shocks & reduces friction at joints
How does the periosteum differ from the endosteum in terms of structure and function?
P - tough layer of dense CT that covers all bones; contains osteogenic cells BV; allows bone to grow in thickness; attch point for lig and tendons
E - single osteoblast layer with CT (thin membrane) that lines medullary cavity; active during repair & remodelling
What does the medullary cavity contain?
fatty yellow bone marrow; reduces bone weight
What does the osseous matrix comprise of?
15% water
30% collage fibers (strength)
55% crystallized mineral salts (hardness)
What occurs during calcification? When does it occur?
- calcium phosphate combines w calcium hydroxide to form hydroxyapatite
- salts and ions are deposited on framework of collagen fibres
- only in presence of collagen fibres!
What are osteogenic cells and what do they do?
- undifferentiated stem cells from mesenchyme (embryonic CT)
- divide to replace themselves and can differentiate into osteoblasts
What are osteoblasts and what do they do?
- form matrix by secreting collagen fibres and depositing mineral salts (responsible for bone calc)
- become osteocytes
*cannot divide
What are osteocytes and what do they do?
- mature cells that no longer secrete matrix
- maintain bone metabolism
*cannot divide
What are osteoclasts and what do they do?
- formed by monocytes
- function in bone resorption
- secrete enz that breakdown ENZ, releasing min/ions into blood
Where are compact bones found?
diaphysis of long bones and beneath periosteum of all bones
Where are spongy bones found?
in the epiphysis of long bones and in flat bones
What are the functions of compact bone?
- provides protection and support (strongest form of BT)
- resists stresses bt weight/movement
How are compact bones arranged?
in parallel units called osteons (concentric rings of matrix of lamellae)
What are osteons?
- rings of calcified matrix (lamellae) surrounding vertically oriented central canal that contains BV and nerves
- aligned parallel along lines of stress
What are lacunae?
concentric lamellae; osteocytes are found in small spaces between lacunae
What are canaliculi? What are found inside them?
channels filled with EC fluid that connect one lacuna to the next to the central canal
inside are extensions of osteocytes
What are the 3 types of lamellae?
concentric, circumferential, interstitial
What does spongy bone consist of?
network of trabeculae; no osteons
What are trabeculae?
lattice of thin plates of bone oriented along lines of stress; space in bt are filled with red bone marrow; consist of lamellae with osteocytes and canaliculi
What are the functions of spongy bone?
support and protects red bone marrow, handles stress from multiple directions
What do nutrient arteries help supply? How?
inner parts of compact bone, spongy bone, red bone marrow
enter through nutrient foramen in center of diaphysis