Calcium and Bone Tutorial

Question 1

what nakes up bone

Answer 1

collagen (protein) calcium phosphate

Question 2

what are the component forms of bone

Answer 2

trabecular - porous sponge like

cortical bone- dense, forms outside of bones

Question 3

what is the mineral that adds strength to bones

Answer 3

calcium phosphate

Question 4

what hormones regulate calcium

Answer 4

parathyroid hormone

calcitonin - a polypeptide

vitamin D - from diet and sunlight

Question 5

what does the parathyroid gland sense in relation to calcium

Answer 5

senses calcium levels via calcium sensing receptors

Question 6

what secretes calcitonin

Answer 6

parafollicular C cell within the thryoid gland

Question 7

where is vitamin D activated

Answer 7

by enzymes within the liver and kidneys

Question 8

what is the role of calcium

Answer 8

maintaining bone strength
excitability of smooth and cardiac muscle
secretion of peptides and hormones in the body
excitability of skeletal neuromuscular junctions
role in blood clotting

Question 9

what is the primary controller of calcium levels in the body

Answer 9

parathyroid hormone

Question 10

what stimulates PTH

Answer 10

hypocalcaemia

Question 11

what is the function of PTH

Answer 11

increase serum calcium and phosphate

activates vit D within the kidney

Question 12

what is the action of PTH on bone

Answer 12

increases osteoclast activity within bones causing increased resorption of bone and calcium to be released

Question 13

what is PTHs action on the kidney

Answer 13

increased tubular resorption of calcium, increasing serum levels

increases the excretion of phosphate in urine

Question 14

what is the active for of vitamin D

Answer 14

1,25 di-OH cholecalciferol

Question 15

what is the role of vitamin D

Answer 15

maintains mineralisation of bone in the body

helps absorption of Ca2+ and PO43 in the intestines

Question 16

when is calcitonin released

Answer 16

in extreme cases of hypercalcaemia

Question 17

what is the role of calcitonin

Answer 17

decreases serum calcium within the body

Question 18

what effect does deficiency or excess of calcitonin have on bone health

Answer 18

none

Question 19

how does calcitonin work

Answer 19

inhibits osteoclasts, decreasing bone resorption and lowering serum calcium

lowers levels of calcium and PO43- by decreasing absorption in the intestines

decreases resorption within the kidneys - Ca2+ and PO43- is excreted in urine

increased calcium movement from plasma to bone

Question 20

what are the consequences of hypercalcaemia

Answer 20

stones, bones, moans and abdominal groans:

• increased stimulation of smooth muscles, nerves and the heart
• tiredness, confusion, depression
• kidney stones
• arrhythmias
• muscle weakness
• constipation

Question 21

what are the consequences of hypocalcaemia

Answer 21

increased excitability of skeletal muscle- tetany of muscles, cramps
pins and needles in hands, feet and lips
contraction of respiratory muscles - asphyxiation

Question 22

what results from hyperparathyroidism

Answer 22

hypercalcaemia 
increased activity of osteoclasts 
osteoporosis - fractures
low serum phosphate levels due to reabsorption of calcium in kidneys 
renal stones

Question 23

what are the subtypes of hyperparathyroidism

Answer 23

primary, secondary and tertiary

Question 24

what is primary hyperparathyroidism caused by

Answer 24

overactivity of parathyroidgland

Question 25

what is secondary hyperparathyroidism caused by

Answer 25

physiological response to low calcium (PTH raised, calcium low)

Question 26

what is tertiary hyperparathyroidism caused by

Answer 26

parathyroid gland becomes autonomous after many years of secondary

Question 27

what can diagnose primary hypercalcaemia (the most common cause)

Answer 27

raised serum calcium raised serum PTH increased urine calcium excretion

Question 28

what is the treatment for hyperparathyroidism

Answer 28

surgery to remove adenoma causing hypersecretion (only if patient has renal stones, renal impairment or severe osteoporosis) high fluid intake avoid vit D and calcium high diet

Question 29

what causes hypoparathyroidism

Answer 29

lack of cells within the parathyroid gland that can secrete PTH - de george = congenital absence of PT glands - destruction via malignancies - autoimmune disease- destruction of parafollicular cells

Question 30

what will be seen in blood serums for hypoparathyroidism

Answer 30

hypocalcaemia and hyperphosphataemia

Question 31

what are the signs of hypoparathryoidism

Answer 31

signs of hypocalcaemia: -chvostek sign (twitching of the face muscle when face nerve gently tapped) -trousseaus sign- inflammation of the blood pressure cuff over systolic will cause tetany of the muscles in the hand and wrist although increased bone calcium and density fractures still high as abnormal

Question 32

what would serum levels in hypoparathyroidism be like

Answer 32

decreased PTH decreased calcium increased PO43-

Question 33

what is the treatment for hypoparathyroidism

Answer 33

calcium and vitamin D supplements

Question 34

what causes pseudohypoparathyroidism

Answer 34

genetic receptor abnormality leading to resistance of the PTH hormone in the body

Question 35

what are serum levels like in pseudohypoparathyroidism

Answer 35

high PTH decreased calcium increased PO43-

Question 36

what are the complications of pseudohypoparathyroidism

Answer 36

``` subcutaneous calcification mental retardation blunting of the 4th metacarpal obesity bone abnormalities ```

Question 37

what can cause lack of vit D

Answer 37

``` lack of sunlight absorption (winter months, skin pigment, not outdoors enough) lack of absorption of the prehormone- poor diet, malabsorption (coeliac) liver failure (stops activation) ```

Question 38

what does lack of vitamin D do

Answer 38

decreases Ca2+ and PO4s absorption within the intestine PTH secretion will be increased as a result lack of bone mineralisation

Question 39

what are the complications of vit d deficiency

Answer 39

rickets and craniotabes (tenderness of the skull presents as neonatal rickets) and widened epiphyses at the wrists and abnormalities in the costochondral joints (these all in children) in adults: osteomalacia- due to lack of mineralisation bones soften becoming more likely to fracture. will have bone and muscle pain. gait deformities may occur due to proximal myopathy