Flashcards in 3.5-Calcium! Deck (20):
What are the two major controllers of blood Ca2+?
PTH and Calcitriol (Calcitonin is minor, can do without)
How much Ca2+ in our body is stored in bone? Teeth?
99% in bone, .6% in teeth :)
What is the breakdown of Calcium in blood? What are the three states and what percentage for each state?
40% bound to Albumin (inactive) , 50% Free(Ionized/actiive), and 10% bound to anions.
Why might a Dr need to correct Ca levels with a formula?
Sometime the percentage breakdowns are off because of low protein levels.
How much Ca2+ is typically eaten per day?
How much Ca2+ is typically removed from the body each day? How much through the GI tract? How much through the kidneys?
1 g out! (Same as in): 850mg Gi Tract, 150mg urine
What percentage of ECM Ca2+ gets filtered by the kidneys, but then is reabsorbed?
98%! (depending on PTH levels)
What are the two methods for absorbing dietary Ca2+? Which one is more efficient?
Transcellular (moving directly thru cells via transporters on both sides) is more efficient then Paracellular (diffusion thru tight jxns). Trancellular proteins are inducible!
What Vitamin do you need to increase trancellular absorption? What hormone controls this?
Vitamin D...PTH controls Vit D
What are the 3 main ways to regulate calcium levels? VERY GENERAL
1. Intestinal Absorption 2.Renal Excretion 3. Controlling bone deposition and abosorption
What is the main message PTH wants to send the body? What 3 main things accomplish this?
"Get more calcium in the blood!" 1. Increases Vit D, for transcellular absorption 2. kidney reabsorption 3. Stimulate Osteoclasts to get it from Bone!
What is the KEY ENZYME that PTH stimulates to convert Vit D to its active form in the kidney? (ready for a long ass name?!
D3-1-alpha-hydroxylase (going from d3 to calcitriol/vit d)
What are the two sources for the Vit D precursors in our body?
Cholesterol activated in the skin (cholcaliferol d3) AND ergo-calciferol (d2) from plants in our diet
What is the protein that the cell will present when vitamin D induces more absorption? Which side of the cell is this on? How does calcium get out the other side?
Cal-Bind-In (D-9-K-->only found in intestines) BOOM easy name... Its on the lumen side to get it from the gut (transports it all the way across)... ATP Ca2+ pumps get the Ca2+ into the blood on the basilar side
What is the rate limiting step in Ca2+ transport?
More calbindin, more Ca2+ absorption
What are the two proteins that escort calcium around int he cell?
Calmodulin and Troponin C
How are we going to tone down blood Ca2+? Where is this hormone made/released from?
Calcitonin!! Perifollicular/c cells of the thyroid
What are the two specific ways calcitonin acts to remove Ca2+ from blood?
1. Stop absorption through the intestines to the blood 2. Stop osteoclasts from releasing Ca2+ into the blood, Activate osteoblasts
What is an iatrogenic cause for hyper calcemia?
DOCTOR induced, giving too much Vit D! Bastards!!