Bones (2) Flashcards
What type of cells does bones have
cells
extracellular matrix
What is bone tissue composed of?
Connective Tissue: supports other tissue/organs, maintain form
2 extracellular components: Organic + Inorganic
Describe Organic Extracellular Component
- 33% of bone ECM (extracellular matrix) is organic
- it is made up of Collagen, Ground substances (proteoglycans)
Function = resists tension
Describe Inorganic ECM
67% of bone matrix is inorganic
- made of Hydroxyapatite + other calcium minerals (mineral salts)
the mineral components makes the bone hard and resistant to compression
What are the 4 types of cells in the Cellular Component of the bone
- Osteogenic cells
- Osteoblasts
- Osteocytes
- Osteoclasts
What do the 4 cells in the bone component maintain
- they maintain bone homeostasis
- it balances the bone destruction and formation that results in the same amount of bone stays the same
What are the functions of the 4 cells in the bone component
Osteogenic cells = stem cells that produce osteoblasts
Osteoblasts = MAKERS - produce new bone matrix
Osteocytes: MAINTAINERS + COMMUNICATION - recycle protein and minerals from matrix, they control activity of Osteoblasts/clasts
Osteoclasts = DESTROYERS - remove bone matrix
What makes up the structure of the bone
- there are 2 types of cells = Compact + Cancellous
- made of the same things but are STRUCTUALLY DIFFERENT
What are the differences between Compact and Cancellous
Compact = Osteon Structure Cancellous = Trabecular structure
What are the 2 subtypes of Compact Bone
1) Macroscopically
2) Microscopically
Describe Macroscopically
- the outer surfaces seem dense and impenetrable
- has foramina/holes for blood supply
Describe Microscopically
- is made up of circumferential lamellae and units called OSTEONS
What are Osteons
Are a longitudinal (lengthwise) unit within Compact Bone
- they provided a pathway for nutrients to get cells in the ECM
What is the Osteon composed of?
- A central canal (contains blood vessels and nerves)
- Lamellae
- Lacunae (lakes for Osteocytes)
- Canaliculi (channels for nutrients through ECM)
what are the functions and the definition of Lamellae
- is a series of cylinders formed of ECM around the central canal
- they form the shape of Osteon
- Collagen fibres within lamellae resist forces
What are Cancellous Bones composed of
- trabeculae (struts of Lamella Bone)
- Marrow fills the cavities between trabeculae
- Osteocytes housed in lacuna in between lamellae/on surface
Why are Trabeculae oriented in certain ways?
- Organisation of Trabeculae resists force from multiple directions
- Directs force from body weight in single direction - down the shaft
- spreads force distally`
What is the Pelvic Girdle Force DIstribution?
- the Trabeculae channels the weight around the ilia into the femora
Describe what Bone Remodeling is
- OSTEOBLASTS add bone matrix in Lamellae to bone surface
- OSTEOCLASTS remove bone from the medullary cavity
Describe what Bone Homeostasis is
- is the balance of OSTEOBLASTS and OSTEOCLASTS
- the process is called REMODELLING
What happens if their is an imbalance of OB/OC activity
- Osteoporosis and osteopenia is when OSTEOCLASTS outweighs OSTEOBLASTS
Describe osteoporosis
Cancellous bone = trabeculae becomes thinner
Compression fractures of vertebrae
What can contribute to getting osteoporosis
- Gender
- Lifestyle factors = exercise, nutrition
- start point
