30 Questions
What percentage of organic material in bones is comprised of Type I collagen?
90-95%
What is the primary function of osteoblasts in bone formation?
Deposition of new bone matrix
What is the primary component of the inorganic material in bones?
Crystalline hydroxyapatite
What percentage of the body's calcium is contained in bones?
99%
What is the function of the proton translocating ATPase in osteoclasts?
Expelling protons across the ruffled border into resorption area
What is the function of osteocytes in bone remodeling?
Respond to mechanical strain and send signals of bone formation or resorption
What percentage of bone is remodeled each year in adult humans?
5-10%
What is the primary function of bone regarding blood cells?
Providing space for bone marrow
Which of the following hormones inhibits osteoclasts?
Calcitonin
What percentage of phosphate in our body is found in bone and teeth as hydroxyapatite crystals?
80%
What is the mature form of parathyroid hormone composed of?
84 amino acids
What is the primary function of osteoblasts?
Forming new bone tissue
What is the primary function of the Golgi apparatus in the processing of pro PTH?
To remove six amino acid residues from the N-terminal
What is the effect of PTH on phosphate levels in the urine?
Decreases phosphate reabsorption in the proximal tubules
What is the effect of PTH on Ca2+ levels in the bones?
Increases Ca2+ mobilization from bones
What is the primary regulator of PTH secretion?
Circulating ionized calcium levels
What is the effect of PTH on Ca2+ absorption from the intestine?
Increases Ca2+ absorption from the intestine
What is the effect of high plasma Ca2+ levels on PTH secretion?
Decreases PTH secretion
What is the effect of calcitonin on plasma calcium levels?
It decreases plasma calcium levels
What stimulates the secretion of calcitonin?
Beta-adrenergic agonists, Cholecystokinin, Dopamine, glucagon, estrogen, and secretin
What is the effect of calcitonin on bone resorption?
It decreases bone resorption
What is the effect of calcitonin on calcium excretion in urine?
It increases calcium excretion in urine
What is the characteristic of osteomalacia?
Deficiency of vitamin D during adulthood
What is the primary cause of osteoporosis?
Estrogen deficiency
What is the direct effect of high PO4 on vitamin D production?
It inhibits α-hydroxylase enzyme
Which of the following is NOT a function of vitamin D?
Inhibiting osteoblasts
What is the role of PTH in the formation of 1, 25 dihydroxycholecalciferol?
It facilitates the formation of 1, 25 dihydroxycholecalciferol
What is the effect of low Ca2+ on PTH secretion?
It increases PTH secretion
What is the source of vitamin D3?
Skin
What is the role of α-hydroxylase enzyme in the kidneys?
It catalyzes the formation of 1, 25 dihydroxycholecalciferol
Learn about the biochemistry of bone and connective tissue, including their composition, formation, and related disorders. Understand the role of organic and inorganic components, such as collagen and hydroxyapatite, in bone structure.
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