3.5-Calcium!

Question 1

What are the two major controllers of blood Ca2+?

Answer 1

PTH and Calcitriol (Calcitonin is minor, can do without)

Question 2

How much Ca2+ in our body is stored in bone? Teeth?

Answer 2

99% in bone, .6% in teeth :)

Question 3

What is the breakdown of Calcium in blood? What are the three states and what percentage for each state?

Answer 3

40% bound to Albumin (inactive) , 50% Free(Ionized/actiive), and 10% bound to anions.

Question 4

Why might a Dr need to correct Ca levels with a formula?

Answer 4

Sometime the percentage breakdowns are off because of low protein levels.

Question 5

How much Ca2+ is typically eaten per day?

Answer 5

1g (1000mg)

Question 6

How much Ca2+ is typically removed from the body each day? How much through the GI tract? How much through the kidneys?

Answer 6

1 g out! (Same as in): 850mg Gi Tract, 150mg urine

Question 7

What percentage of ECM Ca2+ gets filtered by the kidneys, but then is reabsorbed?

Answer 7

98%! (depending on PTH levels)

Question 8

What are the two methods for absorbing dietary Ca2+? Which one is more efficient?

Answer 8

Transcellular (moving directly thru cells via transporters on both sides) is more efficient then Paracellular (diffusion thru tight jxns). Trancellular proteins are inducible!

Question 9

What Vitamin do you need to increase trancellular absorption? What hormone controls this?

Answer 9

Vitamin D…PTH controls Vit D

Question 10

What are the 3 main ways to regulate calcium levels? VERY GENERAL

Answer 10

1. Intestinal Absorption 2.Renal Excretion 3. Controlling bone deposition and abosorption

Question 11

What is the main message PTH wants to send the body? What 3 main things accomplish this?

Answer 11

“Get more calcium in the blood!” 1. Increases Vit D, for transcellular absorption 2. kidney reabsorption 3. Stimulate Osteoclasts to get it from Bone!

Question 12

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?!

Answer 12

D3-1-alpha-hydroxylase (going from d3 to calcitriol/vit d)

Question 13

What are the two sources for the Vit D precursors in our body?

Answer 13

Cholesterol activated in the skin (cholcaliferol d3) AND ergo-calciferol (d2) from plants in our diet

Question 14

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?

Answer 14

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

Question 15

What is the rate limiting step in Ca2+ transport?

Answer 15

More calbindin, more Ca2+ absorption

Question 16

What are the two proteins that escort calcium around int he cell?

Answer 16

Calmodulin and Troponin C

Question 17

How are we going to tone down blood Ca2+? Where is this hormone made/released from?

Answer 17

Calcitonin!! Perifollicular/c cells of the thyroid

Question 18

What are the two specific ways calcitonin acts to remove Ca2+ from blood?

Answer 18

1. Stop absorption through the intestines to the blood 2. Stop osteoclasts from releasing Ca2+ into the blood, Activate osteoblasts

Question 19

What is an iatrogenic cause for hyper calcemia?

Answer 19

DOCTOR induced, giving too much Vit D! Bastards!!

Question 20

What is the magic zone we want to keep blood Ca2+ at?

Answer 20

10mg/dL