Calcium

Question 1

5 nutrients and substances that inhibit calcium absorption

Answer 1

Fiber

Phytic acid

Oxalic acid

Excessive divalent cations (Zn, Mg)

Unabsorbed fatty acid

Question 2

3 nutrients/substances that enhance urinary calcium excreation

Answer 2

Sodium

Protein

Caffeine

Question 3

3 nutrients whose absorption is inhibited by excessive calcium

Answer 3

Phosphorus

Iron

Fatty acids

Question 4

What 3 ways is calcium transported in the body

Answer 4

Bound to proteins (albumin and prealbumin) (40%)
Complexed with sulfate, phosphate, citrate (10%)

Free in the blood (50%)

Question 5

Where is most calcium found

Answer 5

Free in the blood

Question 6

What molecule can increase calcium excretion and absorption

Answer 6

Proteins

Question 7

Where is calcium mainly deposited

Answer 7

In the bone

Question 8

When is PTH secreted

Answer 8

When calcium levels low

Question 9

What is low calciums levels effect on parathyroid gland

Answer 9

Stimulates release of PTH

Question 10

What is PTH effect on bone

Answer 10

Increased osteoclasts activity in bone

Leads to Ca and P resorption

Question 11

What is PTH effect on kidneys

Answer 11

Stimulates 1-hydroxylase activity to increase synthesis of calcitriol

Question 12

What is PTH effect on the intestine

Answer 12

Does not directly act on intestine

Question 13

When is calcitriol secreated

Answer 13

When calcium levels are low

Question 14

What is calcitriols effect on bone

Answer 14

Increases osteoclasts activity and increases proteins involved in bone remodeling

Question 15

What is calcitriols General effect on kidneys

Answer 15

Increases calcium reabsorption

Question 16

How does calcitriol specifically increase calcium resorption in the kidneys

Answer 16

Increase expression of TRPV5 (brush border), increasing synthesis of calbindin D28k (intracellular transport), and Ca-ATPases (basolateral membrane)

Question 17

What is calcitriols effect on the intestine

Answer 17

Increases calcium absorption

Question 18

How does calcitriol specifically increase calcium absorption in the intestine

Answer 18

Increase expression of TRPV6 (brush border), increasing synthesis of calbindin D9k (intracellular transport), and Ca-ATPases (basolateral membrane)

Question 19

When is calcitonin secreated

Answer 19

Calcium levels are high

Question 20

What is calcitonins effect on bone

Answer 20

Inhibits osteoclastic activity

Question 21

What is calcitonins effect on kidneys

Answer 21

Inhibits tubular resorption of calcium

Question 22

When is FGF 23 released

Answer 22

When calcium levels high

Question 23

Where is FGF 23 synthesized

By what?

Answer 23

In bone by osteocytes and osteoblasts

Question 24

What is FGF 23 effect on kidneys

Answer 24

Inhibits synthesis of 1-hydroxylase

Question 25

What is regular extracellular calcium concentration

Answer 25

8.5-10.5 mg/dL

Question 26

4 Characteristics of trabecular bone

Answer 26

Spongy appearance Only 20-25% total bone in body Is found mainly in axial skeleton and ends of long bones More active than cortical

Question 27

3 Characteristics of cortical bone

Answer 27

Compact and dense Is 75-80% of bone in body Mainly found on surfaces of bones and shaft of long bones

Question 28

What do cortical and trabecular bone have in common

Answer 28

Consist of mostly type 1 collagen

Question 29

4 proteins that compose bone

Answer 29

Osteonectin Osteopontin Osteocalcin Matrix Gla protein

Question 30

Osteonectin function

Answer 30

phosphoprotein which binds calcium and collagen

Question 31

Osteopontin function

Answer 31

binds to hydroxyapatite and calcium oxalate

Question 32

Osteocalcin function

Answer 32

secreted by osteoblasts and involved in hydroxyapatite binding and mineral deposition

Question 33

Matrix GLA protein function

Answer 33

promotes calcification of bone and may protect against soft tissue calcification

Question 34

What 2 proteins that comprise bone are vitamin k dependent

Answer 34

Matrix GLA protein Osteocalcin

Question 35

Why are Osteocalcin and matrix GLA protein vitamin K dependent

Answer 35

Vitamin k is cofactor for the carboxylase for the proteins

Question 36

Osteoblasts main classification

Answer 36

Bone building cells

Question 37

2 Osteoblasts functions

Answer 37

Secrete collagen, proteins and ground substance Regulate differentiation of osteoclasts

Question 38

Where do osteoblasts originate

Answer 38

Bone marrow

Question 39

Osteocytes function

Answer 39

Important for maintaining the integrity of surrounding bone

Question 40

Osteocyte are created from?

Answer 40

differentiated osteoblasts (osteoblasts that were incorporated into the bone matrix)

Question 41

Osteoclasts main classification

Answer 41

large and multinucleated cells that break down bone

Question 42

Osteoclast function

Answer 42

Lysosomes in osteoclasts release hydrochloric, citric and lactic acids

Question 43

What is the relationship of serum calcium to bone calcium levels

Answer 43

Occur inversely

Question 44

What hormone does the opposite of PTH and calcitriol

Answer 44

Calcitonin

Question 45

3 Risks for calcium deficiency

Answer 45

Tetany (intermittent muscle contractions that fail to relax) Increased risk for osteoporosis Co-deficiency of Vitamin D Hypocalcemia may lead to hypertension, colon cancer, obesity

Question 46

UL of calcium

Answer 46

UL = 2,500 mg/day

Question 47

Toxicity of calcium can cause what 2 things

Answer 47

Milk alkali syndrome increases risk for kidney stones

Question 48

3 nutrients and substances that enhance calcium absorption

Answer 48

Vitamin D Sugars and sugar alcohols Proteins