Osteoporosis Flashcards
What are the seven important functions of bones?
- Support
- Protect
- Movement
- Mineral and growth factor storage
- Blood cell formation
- Triglyceride storage
- Hormone production
What are osteogenic stem cells?
Progenitor cells that differentiate into osteoblasts
What part of the bone is most affected by osteoporosis?
Cancellous (spongy) bone
What do osteoblasts secrete?
Osteoid (unmineralised matrix)
What cells line the bone? What is their role?
Periosteal and endosteal cells maintain matrix
What do osteocytes sense?
Sense stress and strain
What are the organic components of bone?
- Osteogenic cells
- Osteoblasts
- Osteocytes
- Bone-lining cells
- Osteoclasts
- Osteoid
What is osteoid made up of?
Ground substances and collagen fibres
What gives bone resilience?
Sacrificial bonds in or between collagen molecules
What is the inorganic component of bone? What percentage of the total bone mass does it make up?
Hydroxyampatites (mineral salts), 65% of bone mass
What hormones are responsible for regulation of bone growth?
- Growth hormone
- Thyroid hormone
- Testosterone and oestrogen
What percentage of bone mass is “recycled” due to bone homestasis each week?
5-7%
How often is spongy bone and compact bone replaced by bone homeostasis?
Spongy bone: every 3-4 years
Compact bone: every 10 years
Where in the bone does bone remodelling occur?
- Periosteum
- Endosteum
What is the function of osteoclasts?
- Create depressions or grooves as break down of matrix occurs
- Secretes lysosomal enzymes that digest matrix and protons
- Acidity converts calcium salts to soluble form
What does osteoclast activation depend on?
Parathyroid and thyroid cell-secreted proteins
What are the functions of calcium in the body?
- Nerve impulse transmission
- Muscle contraction
- Blood coagulation
- Secretion by glands and nerve cells
- Cell division
How much calcium is in the body normally?
1200-1400g of calcium in body