Ch 79 Flashcards
What percentage of compact bone is organic and what % is salt deposits?
30% organic and 70% is salt deposits.
What makes up 90-95% of the organic part of a bone?
Collagen fibers.
5-10% of the organic bone is what and what will it do?
Ground substance and it controls salt deposition.
What makes the salt deposits in bone?
Ca and Ph which together make hydroxyapatite.
What part of the bone is for tensile force?
collagen
What part of the bone is for compressional strength?
Hydroxyapatite.
Hydroxyapatite crystals will or will not precipitate in the ECF with supersaturation of Ca, and Ph?
Will not.
What % of total body calcium is in the ECF?
0.1 percent.
What % of calcium is intracellular?
1 percent.
Where is 98% of body calcium stored at?
In the bones.
Besides the bone where else is ca stored at?
Liver and GI tract.
Calcium equilibrium in the blood is important for what?
Proper pH of blood to be maintained.
Osteoclast do what and are how active?
They mobilize bone and are active in less than 1% of bones in adults.
Physical stress on bones controls what?
The rate of deposition.
Fracutres of bones do what?
Maxinally activates osteoblasts.
What is a callus?
When fixing a fracture it is the depostition of ca salts between ends.
What is the normal amount of calcium in the ECF?
9.4 mg/dl.
High levels of calcium in ECF will do what to the nervous system?
Neurological excitability.
Ph or Phosphorus is found where in the body?
1% in ECF, 15% intracellular and 85% is in bones.
Phosphorus assists in what?
Acid-base balance.
What is the main purpose of PTH and where is it made at?
Made in the parathyroid gland it controls the ECF concentration of Ca, and Ph.
What will an over and under active parathyroid gland lead to?
over- Hypercalcemia and osteoporosis. Under- leads to hypocalcemia and tetany.
parathyroid function?
2/4.
Chief cells in the parathyroid gland secrete PTH and are called what when they are inactive?
Oxyphil cells.
What is Osteolysis?
The removal of bone salts caused by PTH activating osteoclasts.
With hypoparathyroidism what happens to Serum levels of Phosphorus?
They are increased.
How can hypoparathyroidism cause death?
Can lead to laryngeal tetany and respiratory obstruction.
How is Hypoparathyroidism treated?
supplements. Instead Vitamin D is given up to 100,000 IU/month, and Ca supplements 1-2 g./day.
Tetany occurs when Ca serum levels fall how low?
6mg/dl or falls by 35%.
Death from low levels of serum Ca occurs at what levels of calcium?
4mg/dl.
What is the usual cause of hyperparathyroidism?
Usually a tumor causing increased secretions of PTH.
Why is hyperparathyroidism common in women?
Because of breast feeding. More Ca is needed in ECF.
What is osteitis fibrosa cystic?
Extensive decalcificatin and large punched-out cystic areas.
Giant cell osteoclast tumors are areas of what?
Extreme osteoclast congregation.
What happens to osteoblasts with hyperparathyroidism?
they fall behind.
Increase concentrations of Ca and Phosphorus in urine leads to what?
Kidney stones.
What will hypercalcemia do to reflexes, cardiac function, and GI contractility?
Decrease these actions.
What happens to our appetite with hypercalcemia?
It decreases.
How will hypercalcemia effect blood pressure?
It gives diastolic blood pressure abnormalities.
What happens with extreme hypercalcemia of 17mg/dl?
Parathyroid poisoning and metastatic calcification.
will it go?
Alveoli, kidney tubules, thyroid gland, mucosa of stomach, artery walls.
What is secondary hyperparathyroidism?
Elevated PTH due to hypocalcemia (if the parathyroid gland is working normally).
What are 2 casues of secondary hyperparathyroidism?
D.
What is the carrier of calcium in ECF?
Albumin.
What happens with normal levels of serum calcium and high PTH?
It is secondary hyperparathyroidism.
What are 2 causes of secondary hyperparathyroidism?
D.
Generally what is the effect of calcitonin?
Opposes PTH it decreases the serum calcium.
What is weaker calcitonin or PTH?
Calcitonin is weaker.
What will dominate or override calcitonin or PTH when both are present?
PTH trumps.
With a thyroid removal what treatment is given to compensate for the loss of calcitonin?
Nothing the effects of calcitonin in adults is small.
What will increase the amount of calcium binding protein (albumin)?
Vitamin D.
How will vitamin D effect ATPase in GI cells?
It increases calcium-stimulated ATPase in GI cells.
How will vitamin D effect alkaline phosphatae in the GI cells?
It increases alkaline phosphatase in the GI cells.
What is a Vitamin D deficiency in childeren called?
Rickets.
Low levels of Vitamin D do what to bones?
Leads to weakened bones.
What is the treatment of rickets?
Calcium, phosphorus and vitamin D supplements.
What is the adult for of rickets called?
Osteomalacia.
Will adults usually have vitamin D deficencies why or why not?
No because their skeletons are mature and they have no increased demand.
What may cause osteomalacia or adult rickets?
Steatorrhea which is a failure to absor fat.
Why will steatorrhea cause osteomalacia?
Vitamin D is fat soluable and calcium forms an insoluable detergent with fat. So calcium and Vitamin D are excreted in the feces instead of absorbed.
What is renal rickets?
kidneys.
When will renal ricktes occur?
In surgical removal, damage, or hemodialysis.
What is congenital hypophosphorusmia?
Vitamin D resistant rickets from reduced reabsorption of phosphorus.
What is the most common bone disease?
Osteoporosis.
Osteoporosis results from what?
Diminished bone matrix not poor bone calcification.
What happens to osteoblasts and osteoclast with osteoprosis?
Osteoblast- activity is less than normal. Osteoclasts- excess activity may be the cause of osteoprosis.
What is a common cause of osteoprosis that we highlighted in class?
Lack of physical stress on bones.
