Osteoporosis Therapies Flashcards
What is the skeleton and what are the major functions of it?
-the skeleton is a rigid supporting structure of the body
-all bones have the same structure, composing of a outer layer called the compact bone (the cortex) and an inner spongy layer in which the bone is arranged in a loose meshed lattice of thin strands called BONE TRABECULAE.
Where is bone marrow found?
This is found between the trabeculae, consisting of fat and blood forming tissue
What is the function of osteocytes?
They become imbedded into the bone matrix during bone formation and they are responsible for sensing and responding to mechanical stimuli.
What is bone?
Bone is a specialised type of connective tissue.
-it is composed of Denise connective tissue framework, saturated with calcium phosphate salts along with calcium carbonate and other minerals.
What are the three different types of bone cells ?
1.osteocytes
2.osteo presenting cells
3.osteoblasts and osteoclasts
What are the three types of joints?
- Fibrous
2.cartilaginous
3.synovial
How are bone cells formed?
Misoncile cells called osteo presenter cells, these stem cells divide to produce daughter cells that can differentiate into osteoblasts.
How do osteoblasts work?
They are active bone forming cells that produce collagen Ashe bone matrix and secrete enzyme alkaline phosphatase, which promotes the deposition of calcium phosphate salts in the bone matrix to calcify bones.
How are osteocytes formed?
As the bone matrix is formed and calcified the osteoblasts become incorporated in the bone and become inactive in mature bone called OSTEOCYTES.
What are osteoclasts and what is their job?
-these are multinucelated cells concerned with bone reabsorption( so the break down of bone)
-they remove bone matrix via phagocytosis and dissolve the bone salts releasing caladium and phosphate ions in circulation.
What happens once the osteoclast resort bone?
Bone matrix bound factors such as TNF-b, IGF1 and other growth factors such as cytokines (IL 6 )are released
What do the released factors work to do?
These factors stimulate osteoblasts which begin to refill the reabsorption cavities excavated by the osteoclasts.
What is a the overall job of parathyroid hormone?
1.increase reabsorption of calcium
2.decrease the reabsorption of inorganic phosphates by the kidney.
Retained calcium and decreased phosphates
-raises calcium plasma levels.
3.can act directly onto the bone cells themselves, levels of parathyroid hormone will bind to cell surface parathyroid hormone receptors on osteoclasts to increase g the expression of osteoclast differentiation factor (RANK L)
-they also reduce tyhe release of OPG (synthetic lung and that stops the binding of rankL to receptor to stimulate osteoclasts.
4.it induces bone marrow stomal cells to secrete cytokines e.g. IL 6 they stimulate osteoclast and bone reabsorption to take place.
What is osteopenia?
This refers to bones being weak but not weak enough to break or fracture a bone. They still maintain a sense of strength.
Bone formation and metabolism are dependant upon a few factors, name a few:
HORMONE INFLUENCE:
-parathyroid Hormone
-calcitonin
-oestrogen
-androgen
-growth hormone
-glucocorticoids
-thyroid hormones
LOCAL REGULATORS OF BONE REMODELLING:
-cytokines e.g. IL6 and IL1
-prostaglandins
-growth factors e.g. IGF-I and TGR-b
Vitamins and minerals:
-calcium
-vitamin D
-magnesium
-postassium
-zinc
-Vitamin B6,9,12
-vitamin E
