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22 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Factors affecting the Growth Plate
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1. Hormones :
Pituitary growth hormone -excess ...giant -deficient… .dwarf Thyroid – deficient = Cretin |
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Bone as a store of mobilizable Ca2+
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Ca2+ is important in:
enzyme activity cell cohesion cell permeability muscle contraction nerve impulse transmission blood clotting |
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% of total Ca2+ of body =
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99%
There is a constant interchange between bone and blood Ca2+ |
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Blood plasma Ca2+ level (9-11mg/100ml) is clearly regulated. Heart may stop if conc. goes too high or breathing
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Heart may stop if goes too high
breathing may cease if level falls too low (respiratory arrest). |
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Mechanisms to mobilize Ca2+
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1 Diffusion from the hydroxyapatite crystals & diffuses into the tissue fluid.
2. Hormonal |
*Note: mature compact bone is more mineralized and is much more stable, its calcium is much less labile, therefore it is also called structural bone.
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Mechanisms to mobilize Ca2+
Hormonal |
matrix are resorbed by the action of parathyroid hormone which acts through stimulating osteoclasts.
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Note: In hyperparathyroidism - there is excessive bone resorption - the bone contains excessive amounts of fibrous tissue and many osteoclasts. The disease is called osteitis fibrosa. The bone is transparent to X-rays and blood calcium is elevated, abnormal deposits of calcium in several organs are seen e.g. kidneys, arterial walls. Bones fracture’s more easily.
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. if blood Ca2+ is low, then what hormone is high =
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parathyroid hormone level increases.
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***
: In hyperparathyroidism - there is excessive bone resorption - the bone contains excessive amounts of fibrous tissue and many osteoclasts. The disease is called osteitis fibrosa. |
*** osteitis fibrosa.
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Mechanisms to mobilize Ca2+
Another hormone called , produced by the parafollicular cells of the thyroid gland It has the same or opposite effect of parathyroid hormone. Its secretion is also governed by direct / indirect feedback = and it lowers or raises the blood Ca2+ level. |
Calcitonin
Opposite Direct Raises |
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Mechanisms to mobilize Ca2+
In pregnancy |
the mother’s bone stores of Ca2+
may be used to provide Ca2+ for the developing skeleton in the fetus and also may be excreted in the milk during lactation |
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In the post-menopausal female, osteoporosis appears to be related to a deficiency in oestrogens.
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deficiency in oestrogens.
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___? stimulates production of Insulin-like growth factors (IGFs) |
Human growth hormone (hGH)
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Excessive production before adult life may result in a giant
Reduced production before adult life may result in a dwarf. In adults, an increase causes acromegaly in which bones (mainly long) become very thick. |
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___? are also needed for normal bone growth. |
Thyroid (T3 & T4) and insulin
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Deficiencies in certain__5ct__,"", may affect bone matrix which becomes so weakened that fractures occur.
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certain minerals (Ca2+, P04 ) and vitamins D, C, and A,
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The bones are weak and bend.
In adults the condition is called = |
osteomalacia
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Vitamin D is essential in absorption of
What organ does the absorption = Vitamin D deficiency results in what Dz in children. = The growth plate is affected since the cartilage matrix does not properly calcify and also the new adjacent osteoid is deficient in Ca. The result is that = |
calcium
from intestines. rickets in children. bones are weak and bend. |
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Vitamin C is necessary for =
Vitamin C deficiency results in = info |
collagen production..
scurvy. |
The organic bone matrix is particularly affected by deficiency in collagen and in glycoproteins. Growth is retarded due to the effect on the growth plate which tends to collapse with associated hemorrhages so that it becomes completely disorganized.
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Vitamin A deficiency:
coordinates the activity of = info |
osteoblasts and osteoclasts. .
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Deficiencies in remodeling may occur with serious complications. e.g. in the skull and spinal column due to lack of remodeling the bone may become thick with compression of the brain and spinal cord.
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Vitamins ___? & ___? also needed for protein synthesis. =
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K
B12 |
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Disorders of bone
Osteogenesis imperfecta is = |
The bones are brittle and break easily.
info |
congenital disorder in which the particular type of collagen normally present in bone matrix is deficient and defective.
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Bone Tumors benign
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osteoblastoma, osteoclastoma
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Osteosarcomas show pleomorphic and mitotically active osteoblasts associated with osteoid.
Most cases of this aggressive malignant tumor occur in adolescents and young adults. The lower end of the femur, the upper tibia, and the upper humerus are the most common locations. |
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Bone Tumors
***the site of metastases The most frequent bone metastases are from = 5ct |
breast, lung, prostate, kidney, and thyroid tumors.
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