Calcium Homeostasis
First, Let’s Take a Look at This
Diagram…… Homeostasis of Calcium
Where Do I Get My Calcium?
% 70 inorganic matrix composed of
Calcium Salts in Hydroxyapatite
Ca10(PO4)6(OH)2.
The skeleton...
Resorption and Remodeling
Resorption
Osteoclasts do this
using HCL and ACID
PHOSPHATASE to
dissove bone matrix
Remodeli...
Its Role in Calcium
Homeostasis
VITAMIN D
TThe vitamin That Works
Like a hormone
How Does “D” Compare To
Hormones?
Vitamin D3 is not secreted by a classical endocrine
gland, the active form of the hormo...
To Make Me D, Warm Me Up and
Hydroxylate Me..3X!
So..Exposure to Sun and Then, Fortified
Foods….Give Us the D We Need
How Does Vitamin D Facilitate Calcium
Absorption in the Intestines??
IN THE INTESTINE
It facilitates intestinal absorption of calcium,
as well as stimulates absorption of phosphate
and magnes...
The vitamin D form, 1,25-
dihydroxcholecalciferol [1,25(OH)2D3],
1. stimulates the synthesis of the epithelial calcium
ch...
Vitamin D: Its Role is ABSORPTION of CALCIUM ,and
to a lesser extent, Phosphorous, from the Small
Intestine and Duodenum.
Once joined with ingested vitamin D,
facilitate increased serum calcium
levels .
Shows Expressed Calbindins and
How the fa...
Calcium Absorption Enhanced by Carrier
Protein Calbindin

Calcium absorption is transport across the
epithelial cell, which is greatly enhanced
by the carrier protein calbindin, t...
Calcitriol Raises Blood
Calcium in 3 Ways:
1. Increases Ca++
absorption by the small
intestine.
2. Increases Calcium
(and ...
Let’s Look A Bit Closer at RANK L
But, I thought Vitamin D HELPED US
retain Calcium?
 Yes, It does. So, although there is some
proliferation of osteoclasts...
Vitamin D has also been shown to play an
important part in regulating the
proliferation and differentiation
of both types ...
Consider Calcium Itself
Got Milk?
Ages 19 -50 : need 1000 mg/ day in diet
Major Food Sources Include:
Dairy products Others: dark leafy greens
S...
Calcium Is Needed For:
Bone Matrix (70%
Ca0H in form of
Hydroxyapatite)
Muscle Contraction
Nerve Impulses
Blood Clotti...
Calcium Homeostasis
We need to maintain a calcium
blood level of 9-11 mg/ 100ml
What HOMEOSTASIS IS NOT
MAINTAINED? WHAT ARE THE
IMMEDIATE DANGERS?
Blood Calcium TOO LOW…We call this
TETANY: Inability ...
Parathyroid Gland Anatomy
Four Parathyroid
glands are usually
found posterior to
the thyroid gland
Total weight of
parat...
Low Blood Calcium
• Parathyroid gland releases parathyroid hormone
• Stimulates osteoclasts to resorb Ca++
• Blood calcium...
Calcitonin
Calcitonin is a peptide
hormone secreted by the
parafollicular or “C” cells of
the thyroid gland
It is synthe...
Control of Calcium Homeostasis
The Role Calcitriol plays in
maintaining normal blood
calcium concentration.
Correction for
Hypocalcemia
Correction for
Hypercalcemia
Osteoblasts- cells that form
bone during both
ossification and
remodeling
Osteoclasts- Cells
responsible for bone
resorpti...
Reversing Things A Bit:
Can I Deplete My Calcium Storage
By Lifestyle?
IF SO…….HOW???
35
Nutrition and OP
Aside from getting enough calcium and
Vitamin D, the single most important point
is . . .
Avoid dietar...
36
Preventable Risks
Sedentary lifestyle (REMEMBER WOLF”S
LAW)
Insufficient calcium or vitamin D intake
Diet high in me...
REMEMBER
Stress causes …bone building
Lacking of use…..bone resorption
LET’s add to this…acididosis-like
condition in t...
How Does Eating Too Much Meat
Cause Our Bones To Thin?
39
How Does This Calcium Depletion
Occur?
When you take in more protein than you need,
your body cannot store extra prote...
COLA DRINKS…..BAD FOR
BONES
IN SEVERAL STUDIES IT HAS BEEN
SHOWN THAT:
Intake of cola, but not of other carbonated
softd...
What are the consequences of
INEFFICIENT CALCIUM early in life?
Rickets
The specific radiographic
features of rickets reflect
the failure of cartilage
calcification and
endochondral oss...
Later in Life….Osteoporosis and
Osteomalacia
Osteoporosis is the loss of bone density
Osteomalacia is lack of mineraliza...
Calcium
Calcium
Calcium
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Calcium

  1. 1. Calcium Homeostasis
  2. 2. First, Let’s Take a Look at This Diagram…… Homeostasis of Calcium
  3. 3. Where Do I Get My Calcium? % 70 inorganic matrix composed of Calcium Salts in Hydroxyapatite Ca10(PO4)6(OH)2. The skeleton is resevoir for the minerals Calcium (and phosphorous). Resorption: the process of dissolving bone and releasing its minerals into the blood for other uses. The OSTEOCLAST secretes ACID PHOSPHATASE or sometimes HCL to digest bone matrix. Secreted by lysosomes.
  4. 4. Resorption and Remodeling Resorption Osteoclasts do this using HCL and ACID PHOSPHATASE to dissove bone matrix Remodeling Ostoblasts do this Collagen fibers and hydroxyapatite matrix
  5. 5. Its Role in Calcium Homeostasis VITAMIN D TThe vitamin That Works Like a hormone
  6. 6. How Does “D” Compare To Hormones? Vitamin D3 is not secreted by a classical endocrine gland, the active form of the hormone is released from the kidney and acts at distant sites or locally. Each of the forms of vitamin D is hydrophobic, and is transported in blood bound to carrier proteins. Only a very remains in a free form in the circulation and has a serum t1/2 of about 5 hours small proportion of vitamin D
  7. 7. To Make Me D, Warm Me Up and Hydroxylate Me..3X!
  8. 8. So..Exposure to Sun and Then, Fortified Foods….Give Us the D We Need
  9. 9. How Does Vitamin D Facilitate Calcium Absorption in the Intestines??
  10. 10. IN THE INTESTINE It facilitates intestinal absorption of calcium, as well as stimulates absorption of phosphate and magnesium ions. In the absence of vitamin D, dietary calcium is not absorbed at all efficiently. Vitamin D stimulates the expression of a number of proteins involved in transporting calcium from the lumen of the intestine, across the epithelial cells and into blood.
  11. 11. The vitamin D form, 1,25- dihydroxcholecalciferol [1,25(OH)2D3], 1. stimulates the synthesis of the epithelial calcium channels in the plasma membrane calcium pumps , and 2. induces the formation of the calbindins.
  12. 12. Vitamin D: Its Role is ABSORPTION of CALCIUM ,and to a lesser extent, Phosphorous, from the Small Intestine and Duodenum.
  13. 13. Once joined with ingested vitamin D, facilitate increased serum calcium levels . Shows Expressed Calbindins and How the facilitate transport of Calcium
  14. 14. Calcium Absorption Enhanced by Carrier Protein Calbindin 
  15. 15. Calcium absorption is transport across the epithelial cell, which is greatly enhanced by the carrier protein calbindin, the synthesis of which is totally dependent on vitamin D
  16. 16. Calcitriol Raises Blood Calcium in 3 Ways: 1. Increases Ca++ absorption by the small intestine. 2. Increases Calcium (and Phosphate ) resorption from the skeleton. It binds to hematopoietic stem cells and causes differentiation of osteoclasts. 3. Weakly promotes the reabsorption of Calcium ions by the kidney cells (less calcium excreted)
  17. 17. Let’s Look A Bit Closer at RANK L
  18. 18. But, I thought Vitamin D HELPED US retain Calcium?  Yes, It does. So, although there is some proliferation of osteoclasts the  NET RESULT IS: CALCIUM ABSORPTION and REMODELING….Outweighs RESORPTION…. Because…
  19. 19. Vitamin D has also been shown to play an important part in regulating the proliferation and differentiation of both types of bone remodeling cells - those responsible for bone breakdown and those that reform the bone anew…and more.
  20. 20. Consider Calcium Itself
  21. 21. Got Milk? Ages 19 -50 : need 1000 mg/ day in diet Major Food Sources Include: Dairy products Others: dark leafy greens Sardines w/ bones Fortified cereals Most Tofu
  22. 22. Calcium Is Needed For: Bone Matrix (70% Ca0H in form of Hydroxyapatite) Muscle Contraction Nerve Impulses Blood Clotting Cellular Metabolism
  23. 23. Calcium Homeostasis We need to maintain a calcium blood level of 9-11 mg/ 100ml
  24. 24. What HOMEOSTASIS IS NOT MAINTAINED? WHAT ARE THE IMMEDIATE DANGERS? Blood Calcium TOO LOW…We call this TETANY: Inability for muscles to relax ( muscles tremer i.e carpopedal spasms and larngospasms….shuts off air… and can cause suffocation.. BLOOD CALCIUM TOO HIGH…..Its called Hypercalcemia…sluggush nervous system. And possible cardiac arrest.
  25. 25. Parathyroid Gland Anatomy Four Parathyroid glands are usually found posterior to the thyroid gland Total weight of parathyroid tissue is about 150mg Parathyroid hormone (PTH) is made by these glands
  26. 26. Low Blood Calcium • Parathyroid gland releases parathyroid hormone • Stimulates osteoclasts to resorb Ca++ • Blood calcium rises • Promotes the final step of Calcitriol synthesis by kidneys Feedback Inhibition High Blood Calcium • Inhibits parathyroid gland
  27. 27. Calcitonin Calcitonin is a peptide hormone secreted by the parafollicular or “C” cells of the thyroid gland It is synthesized as the preprohormone & released in response to high plasma calcium Calcitonin acts on bone osteoclasts to reduce bone resorption. Net result of its action is a decline in plasma calcium & phosphate
  28. 28. Control of Calcium Homeostasis The Role Calcitriol plays in maintaining normal blood calcium concentration.
  29. 29. Correction for Hypocalcemia
  30. 30. Correction for Hypercalcemia
  31. 31. Osteoblasts- cells that form bone during both ossification and remodeling Osteoclasts- Cells responsible for bone resorption.(FROM Blood) Vitamin D- plays a key role in regulating the proliferation and differentiation of both of these cells
  32. 32. Reversing Things A Bit: Can I Deplete My Calcium Storage By Lifestyle? IF SO…….HOW???
  33. 33. 35 Nutrition and OP Aside from getting enough calcium and Vitamin D, the single most important point is . . . Avoid dietary approaches that deplete calcium!! OP : stands for Osteoporosis
  34. 34. 36 Preventable Risks Sedentary lifestyle (REMEMBER WOLF”S LAW) Insufficient calcium or vitamin D intake Diet high in meat-based protein Excessive caffeinated beverages if low calcium intake Cola drinks Alcohol consumption,
  35. 35. REMEMBER Stress causes …bone building Lacking of use…..bone resorption LET’s add to this…acididosis-like condition in the blood…. ..BONE RESORPTION!!! Here’s where the excess protein, cola and caffeine will come into play.
  36. 36. How Does Eating Too Much Meat Cause Our Bones To Thin?
  37. 37. 39 How Does This Calcium Depletion Occur? When you take in more protein than you need, your body cannot store extra protein (animal protein is more dense than plant protein so we get more protein than we need It converts amino acids into organic acids that acidify the bloodstream. The kidneys neutralize the acidity by pushing large amounts of calcium into the blood and then out via urine.
  38. 38. COLA DRINKS…..BAD FOR BONES IN SEVERAL STUDIES IT HAS BEEN SHOWN THAT: Intake of cola, but not of other carbonated softdrinks, is associated with low (BONE MINERAL DENSITY) BMD in women. Data is collected from Femoral Neck
  39. 39. What are the consequences of INEFFICIENT CALCIUM early in life?
  40. 40. Rickets The specific radiographic features of rickets reflect the failure of cartilage calcification and endochondral ossification and therefore are best seen in the metaphysis of rapidly growing bones ). The metaphyses are widened, uneven, concave, or cupped and because of the delay in or absence of calcification, the metaphyses could become partially or totally invisible.
  41. 41. Later in Life….Osteoporosis and Osteomalacia Osteoporosis is the loss of bone density Osteomalacia is lack of mineralization
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