Final: Calcium (Ca)

Question 1

What are the functions of intracellular Ca?

Answer 1

Critical for enzyme activity and cell function (Endocrinology), 2nd messenger for hormone signals
(1/10,000 of EC Ca)

Question 2

What are the functions of extracellular Ca?

Answer 2

Skeletal tissue, transmission of nerve impulses, excitation of skeletal and cardiac muscles, blood clotting, component of milk and eggshells

Question 3

Where is most of body Ca found and what %?

Answer 3

Bone; 99.5%

Question 4

What are normal plasma Ca [ ]s?

Answer 4

10 mg/dL OR
2.5 mM/L OR
5 mEq/L

Question 5

What % of Ca is bound to protein?

Answer 5

45%

Question 6

What % of Ca is bound to anions?

Answer 6

5%

Question 7

What % of Ca is ionized?

Answer 7

50%

Question 8

What are Ca levels in ACUTE hypocalcemia?

Answer 8

< 6.5 mg/dL

Question 9

What are Ca levels in CHRONIC hypocalcemia?

Answer 9

< 9 mg/dL

Question 10

What are symptoms of acute hypocalcemia?

Answer 10

Hyperexcitable nerves –> tetany
Lack of excitation across myoneural junction –> paresis
Reduced cardiac muscle strength = reduced cardiac output

Question 11

What are symptoms of chronic hypocalcemia?

Answer 11

Bone dissolution, osteoporosis, osteodystrophy

Question 12

What are Ca levels in hypercalcemia?

Answer 12

> 11.5 mg/dL

Question 13

What are symptoms of hypercalcemia?

Answer 13

Calcification of soft tissues (esp. kidney)

Question 14

What happens physiologically to induce flaccid paralysis in ruminants?

Answer 14

Hypocalcemia –> lack of Ca prevents release of ACh at motor end plate

Question 15

What is the predominant clinical sign of hypocalcemia in ruminants?

Answer 15

Flaccid paralysis

Question 16

What is the predominant clinical sign of hypocalcemia in non-ruminants?

Answer 16

tetany

Question 17

What gland can sense any reduction in blood Ca concentration and where is it located?

Answer 17

Parathyroid glands; near the thyroid

Question 18

What level of blood Ca is critical?

Answer 18

9-10 mg/dL

Question 19

How do parathyroid glands respond to low levels of Ca?

Answer 19

Secrete PTH into blood

Question 20

What type of bone is usually affected by PTH?

Answer 20

Spongy/trabecular bone

Question 21

What occurs during osteocytic osteolysis?

Answer 21

PTH stimulates osteocytes to pump Ca from canaliculi back into the extracellular fluid.

Question 22

Osteoclasts are under control of _____.

Answer 22

PTH

Question 23

Active transport of Ca is controlled by _____.

Answer 23

1,25-dihydroxyvitamin D

Question 24

What is produced by the thyroid gland in response to hypercalcemia?

Answer 24

calcitonin

Question 25

What 2 things does calcitonin do?

Answer 25

1. Inhibits renal reabsorption of Ca from glomerular filtrate
2. Inhibits bone Ca resorption

Question 26

What are good sources of Ca?

Answer 26

Ca carbonate or Ca chloride, forages, legumes

Question 27

What are poor sources of Ca?

Answer 27

Grains

Question 28

What are some diseases of Ca deficiency?

Answer 28

1. Rickets in younger animals (although usually by Vit D or Phos deficiency)
2. Osteoporosis/osteomalacia (adult Rickets)
3. Lactational osteoporosis
4. Caged layer fatigue
5. Nutritional Secondary Hyperparathyroidism

Question 29

What are some symptoms of rickets in young animals?

Answer 29

Widened growth plate, enlarged/painful joints, bowing of legs, short stature, costochondral junctions readily palpable, bones rubbery and easy to bend, rosary bead lesions, fractures

Question 30

What are symptoms of osteomalacia (adult rickets)?

Answer 30

Lesion at sites of bone remodeling

Question 31

What happens in osteoporosis?

Answer 31

Animal needs to pull Ca, so pulls it from bones

Question 32

What is lactational osteoporosis?

Answer 32

Bone is sacrificed to keep Ca levels normal in milk and blood; is reversible

Question 33

What is NSHP?

Answer 33

Diet Ca is inadequate so body responds by increasing PTH.

• Increases renal reabsorption of Ca
• Increases osteoclastic bone resorption
• Bone Ca content reduced
• Production of 1,25-dihydroxyvitamin D increased

Question 34

What is osteodystrophy?

Answer 34

Ca deficiency accompanied by excessive Phos in adults

“Rubber jaw” and loose teeth

Question 35

What is osteolysis?

Answer 35

Sites of bone radiolucency - secondary to infection and inflammation of bone region

Question 36

What is Bighead disease?

Answer 36

NSPH of horses caused by diets high in P and low in Ca

• Excessive grain feeding (high phytate)
• High levels of oxalate in hay = prevents Ca absorption

Question 37

What are symptoms of Bighead disease?

Answer 37

Thickened flat bones of skull to give head a swollen appearance
Shifting lameness due to tendon and ligament avulsions, bone microfractures

Question 38

What are 3 reasons why iguanas and turtles in captivity may develop NSPH?

Answer 38

1. Diets based on meat or fruits (no Ca) (add limestone)
2. Diets low in vitamin D and animals caged indoors (need sun lamps)
3. Temp may be too low to promote diet digestion (keep temp high)

Question 39

What is caged layer fatigue?

Answer 39

Hen with hypocalcemia utilizes bone Ca to provide eggs with Ca, results in leg fractures/osteoporosis.

Question 40

What is milk fever?

Answer 40

Calcium deficiency (and metabolic alkalosis), occurs mainly in cows after calving but can also occur in goats.
(Blood Ca goes < 5mg/dL)

Question 41

What is the tx for milk fever?

Answer 41

IV Ca immediately

Question 42

What can cause milk fever?

Answer 42

Pre-calving diets that are too high in K and/or Na, and also hypomagnesemia.

Question 43

How can you prevent milk fever?

Answer 43

Feed low K, high Ca diets before calving. (any anion, really, will help prevent alkalosis)