Mineral Homeostasis and Balance Flashcards
Calcium is important for what general functions in the body?(4-8 points)
membrane excitation, membrane stabilization, muscle contraction, neurotransmitter release, clotting, hormone secretion coupling, neurotransmitter release and constituent of bone and teeth
What is the major intracellular function of phosphate?
phosphorylation, formation of high energy bonds, coordinating a myriad of delicate intracellular functions
What is the affect of parathyroid hormones on the kidneys when considering phosphate ?
It stimulates the decrease reabsorption of phosphate in the proximal tubule
The facilitative diffusion of calcium in the GIT increases with increase up take of calcium or decreases with increase uptake of calcium?
It decrease with increase uptake of calcium
What cell organelle plays a critical role in the capture of calcium and the packaging of calcium phosphate into vesicles?
mitochondria
How does the GIT contribute to calcium homeostasis?
absorption
Do osteoclast have one nuclei or many nuclei?
They have many nuclei, 10-20 or up to 100 if it is a giant nuclei
Why would receiving a large volume of blood have a specific effect on your electrolyte balance?
Citrate is an anti-coagulant found in blood which binds to calcium; therefore, decreasing the free calcium levels in the blood
How does PTH affect bone crystal formation?
It does not favor bone crystal formation due to the fact that calcium rose while phosphate fell
What is the genearal purpose of hepcidin?
It causes degradation of ferroportion, thus blocking iron flow into plasma
How does the bone contribute to calcium homeostasis?(3 points)
formation, mineralization and resorption of bone
After osteoblast form the bone matrix, where do they go and what type of cells do they become?
they become osteocytes and they become trapped in the bone matrix
Patients with alkalosis are more prone towards what muscular disorder? Why?
`tetany. Alkanity promotes precipitation of calcium phosphate while acidity decrease precipitation of calcium phosphate.
What is the mature form of bone mineral?
hydroxyapatite
FGF23 is released by what type of cells? This is done in response to what?
FGF is release by osteocytes in response to elevated levels of calcitriol
How does dopamine affect the secretion of calcitonin?
increases the secretion
How does intermittent PTH affect bone mass? How does activated leptin affect bone mass?
intermittent PTH increase bone mass. Activated leptin decreases bone mass
What could be general causes to abnormal mineralization of bone?(3-5 points)
calcium deficiency, phosphate deficiency, bone cell dysfunction, mineralization inhibitors and abnormal collagen
For the expression of the full range of effects of PTH, what is required?
Vitamin D
What is a common musculoskeletal disease that is caused by vitamin D deficiency?
Ricketts and osteomalacia
Activation of 1-25-(OH)2D3 takes place via the levels of what factors in the blood?(6 points)
GH, prolactin, PTH, phosphate deficiency, vitamin D deficiency and estrogen
Does calcitonin increase or decrease bone mass?
calcitonin increases bone mass
Where is the majority of calcium found in the human body?
bone
What type of cells form bone?
osteoblast
How does estrogen affect the secretion of calcitonin?
increases the secretion?
An increase amount of ECF calcium has what affect on membrane polarization?(2 points)
It causes membrane hyper polarization, it decreases neuronal excitability
How does high plasma 1,25-(OH)2-Vitamin D affect PTH secretion?
It inhibits PTH secretion
What is the more pronounced but delayed action of PTH?(osteoclast activity and bone resorption)?
Activate osteoclasts and increase bone resorption
How does ghrelin effect food intake?
It increases food intake
PTH hormone increase what when it comes to bone construction? (2 points)
Bone resorption and bone formation
A decreased amount of ECF calcium has what affect membrane polarization?(3 points)
It causes membrane depolarization, leads to neutral excitability, i.e., hypocalcemic tetany
What are the four steps of bone remodeling?(4 points)
activation, resorption, reversal and formation
How does PTH interact with the intestine?(2 points)
It increase calcium and phosphate absorption indirectly via the action of vitamin D
Does increased or decrease ECF calcium lead to muscle paralysis?
increased calcium ECF
45% of the calcium bound to something in the blood is bound to what general substance?
plasma proteins
How does mechanical load affect bone mass?
Mechanical load increases bone mass
How does Leptin effect food intake?
It decreases food intake
Does acidity increase ionize calcium or decrease? Why?
Acidity increases ionize calcium because it decreases plasma protein binding of calcium
Is Rickets a disease due to a lack of calcium or a lack of phosphate?
A lack of phosphate
The active transport of calcium in the GIT is dependent upon what?
Vitamin D
How does increase in plasma phosphate affected PTH secretion?
It increases PTH secretion
The small amount of calcium outside of bone is bound or free?
Both, 55% bound and 45% free
How does hypomagnesemia affect PTH secretion?
It decreases PTH secretion
Is bone resorption via vitamin D independent of PTH?
Yes
What type of reabsorption of calcium takes place in the kidney?(2 points) Where does each take place?(4 points)
Passive paracellular takes place in the proximal tubule and the thick ascending limb. Active transcellular takes place in the thick ascending limb and the distal tubule.
What controls the amount of free phosphate in the blood?(3 points)
controlled by the kidneys plus effects of PTH and FDF23
What is bone considered to be bifunctional?
Bone is considered to be bifunctional because it can perform extensive remodeling due to weight bearing effects and it can release calcium into the ECF to maintain electrolyte balance of calcium
What are the three major locations in the body where calcium homeostasis is maintained?(3 points)
bone, GI tract and kidneys
What type of cells derive osteoblast?
mesenchymal stem cells
Peak bone mass and rate of bone loss are influenced by:(2-4 points)
genetics, weight bearing activity, calcium nutritional state, and reproductive endocrine status
Where is the majority of phosphate found in the human body?
bone
If you acutely consume a lot of soda, what does that do your body electrolyte balance?
The phosphate will bind to the calcium and decrease the free plasma calcium levels
How does Vitamin D affect these values: [Ca2+]plasma, [PO4-]plasma, [Ca2+]urine and [PO4]-urine?
Increase, increase, decrease, decrease
Is estrogen a pro-resorptive and calciotropic factor or a anti-resorptive and anabolic factor?
Estrogen is an anti-resorptive and anabolic factor
Parathyroid hormone and vitamin D stimulate osteoblasts to secrete what factors which stimulate osteoclasts to reabsorb bone? 2 points
IL6, and Rank-L
With regard to calcium homeostasis, the dominant effect of PTH one bone is what?
bone resorption
What type of absorption of calcium takes place in the GIT?(2 points)
facilitate diffusion and active transport
The small amount of phosphate outside of the bone is bound or free?
Both, 50% for each
The total amount of phosphate in the body is 500-800 grams. 85% of this is bound to what?(2 points) The rest if primarily where?
85% of phosphate in the body is bound to teeth and bone. The rest is primarily intracellular.
How does calcitonin affect these values: [Ca2+]plasma, [PO4-]plasma, [Ca2+]urine and [PO4]-urine?
decrease, decrease, increase, increase
What type of cells synthesize calcitonin?
parafolicullar cells in the thyroid gland
How do gonadal steroids affect these factors: osteoclast activity, bone resorption, osteoclast apoptosis, osteoblast apoptosis?
decrease, decrease, increase, decrease
how does gastrin, CCK, glucagon and secretin affect the secretion of calcitonin?
increases the secretion of calcitonin
How does glucocorticoids affect these values: [Ca2+]plasma and [Ca2+]urine ?
decrease, increase
Does estrogen increase or decrees bone mass?
estrogen increases bone mass
What are the three special properties of parathyroid chief cells?(3 points)
thye replicate when chronically activated, they can synthesize & store large amounts of PTH, they can rapidly secrete stored hormone in response to changes in blood calcium
How does the body regulate the solubility of calcium and phosphate?
The calcium and phosphate product are regulated quite heavily
How does CT affect the action of 1-alpha-hydroxylase?
inhibits the action of that enzyme
Osteoporosis usually has an excess of what hormonal group?
Glucocorticoids
A large amount of what mineral is found in colas and sodas?
phosphate
Paresthesia is caused by hypocalcemia or hypercalcemia?
Hypocalcemia
During the postmenopausal phase, what happens when comparing the relative activity of osteoclasts and osteoblasts?
There is a relative increase in the osteoclastic activity and a relative decrease in the osteoblastic activity
How does the thyroid hormone affect the listed factors: bone resorption, bone formation?
There is a relative increase in bone resorption and a relative decrease in bone formation
How does FGF23 affect the kidneys?
It decreases the expression of the sodium phosphate cotransporter in the proximal tubule which in turn decreases the reabsorption of phosphate in the kidneys.
What factors leads to the inactivation of the active form of Vitamin D?(3-4)
high plasma calcium high plasma phosphate, high 1-25-(OH)2D3 and CT
How do glucocorticoids affect these factors: osteoblast activity, osteoblast apoptosis?
decrease, increase
What is the short term action of PTH on bone?(4 points)
acts on plasma membrane of osteocytes to take up more calcium and phosphate form lacunal fluid and adjacent bone crystals
Vitamin D is needed for the active uptake of what minerals/nutrients?(3 points)
phosphate, calcium and magnesium
How do the kidneys maintain calcium homeostasis?
It increases calcium reabsorption when needed
How does Hypercalcemia affect the kidney, GI tract, and the nervous system generally speaking?
associated with peptic ulcer disease, neurological deiseases, and kidney stone.
Is bone resorption via vitamin D dependent on PTH?
Yes
What vitamins/hormones play a major role in calcium homeostasis?(3 points)
calcitonin, vitamin D and parathyroid hormone
Is prolatctin an anti-resorptive and anabolic factor or an pro-resorptive and calciotropic factor?
pro-resorptive and calciotropic factor
How do glucocorticoids affect bone mass?
Glucocorticoids increase bone mass
What is the affect of parathyroid hormone on the bones?
It stimulates the loss of calcium and phosphate in the bone
What is the relative solubility of calcium phosphate in water?
It is very low
How does PTH affect these values: [Ca2+]plasma, [PO4-]plasma, [Ca2+]urine and [PO4]-urine?
Increase, decrease, decrease, increase
What controls the amount of free calcium in plasma?(2 points)
Vitamin D and PTH
Is tetany caused by hypercalcemia or hypocalcemia?
Hypocalcemia
