Calcium

Question 1

what are the functions of calcium?

Answer 1

bone and tooth structure, mineral store, action potentials, membrane excitability, 2nd messenger, co-factor in metabolic pathways, blood clotting

Question 2

what are the 2nd messenger functions of calcium?

Answer 2

muscle: excitation-contraction coupling, gland secretion, non-steroid hormone action

Question 3

what is diffusible calcium?

Answer 3

ionised calcium and calcium bound to citrate

Question 4

what is non-diffusible calcium?

Answer 4

calcium bound to protein

Question 5

how does calcium enter the body?

Answer 5

diet

Question 6

once in the body where are all the places that calcium goes?

Answer 6

GI tract, plasma and interstitial fluid, exchangeable bone, stable bone, kidney

Question 7

how does calcium leave the body?

Answer 7

faeces and urine

Question 8

what controls calcium homeostasis?

Answer 8

parathyroid hormone, calcitonin, vitamin D

Question 9

where is the parathyroid hormone secreted from?

Answer 9

parathyroid glands in response to low plasma calcium concentration

Question 10

how does the parathyroid hormone increase plasma calcium?

Answer 10

increase resorption of bone (osteoclasts), increase calcium resorption in kidney (with phosphate resorption), increase uptake of calcium from the intestines (assisted by vitamin D)

Question 11

where is calcitonin secreted from?

Answer 11

thyroid glands in response to high plasma calcium concentrations

Question 12

how does calcitonin decrease plasma calcium?

Answer 12

increase formation of bone (osteoblasts), decrease calcium resorption in kidney

Question 13

how does vitamin D get into the body?

Answer 13

dietary vitamin D and 7-dehydrocholesterol synthesised in the skin

Question 14

how does vitamin D affect calcium in the intestine?

Answer 14

promotes calcium absorption

Question 15

how does vitamin D affect calcium in the kidney?

Answer 15

promotes calcium retention and phosphate retention

Question 16

how does vitamin D affect calcium in the bone?

Answer 16

promotes calcium release and phosphate release

Question 17

how does vitamin D affect calcium in plasma?

Answer 17

promotes increased levels of calcium and phosphate due to the actions on the intestine, kidney and bone

Question 18

what hormones increase bone formation and bone mass?

Answer 18

calcitonin, growth hormone, IGF-1, insulin, oestrogen, testosterone

Question 19

what hormones increase bone resorption and decrease bone mass?

Answer 19

cortisol, PTH and thyroid hormones

Question 20

what is the function of osteoblasts

Answer 20

synthesise and secrete collagne fibres forming a matrix later mineralised by calcium salts

Question 21

what are osteocytes?

Answer 21

trapped osteoblasts in the bone matrix

Question 22

where are the osteocytes?

Answer 22

lie within the bone lacunae and contact other cells via long cytoplasmic processes

Question 23

what are osteoclasts?

Answer 23

large, multinucleate cells, dervied from macrophages that resorb bone

Question 24

where do osteoclasts lie?

Answer 24

lie in depressions

Question 25

what is hypercalcaemia?

Answer 25

raised calcium concentration

Question 26

what is hypocalcaemia?

Answer 26

reduced calcium concentration

Question 27

what is hypocalcaemic tetany?

Answer 27

decreased calcium concentrations

Question 28

what is the cause of hypocalcaemic tetany?

Answer 28

decreased calcium intake, excessive calcium loss, alkalosis

Question 29

what does low calcium lead to?

Answer 29

increased nerve excitability

Question 30

what are the signs of increased nerve excitability?

Answer 30

pins and needles, muscle spasms

Question 31

how do you combat hypocalcaemia?

Answer 31

trap CO2 in the patients lungs which is achieved by rebreathing expired air from a bag

Question 32

what is osteitis fibrosa cystica and what is it a result of?

Answer 32

areas of demineralisation in skull and leg bones and is a result of hyperparathyroidism

Question 33

what is hypoparathyroidism

Answer 33

defective mineralisation of teeth due to low blood calcium levels due to undersecretion of PTH

Question 34

what is vitamin D deficiency?

Answer 34

dietary deficiency, failure to synthesise in body, decreased calcium uptake from GI tract, undermineralised bone

Question 35

what are bones like in a patient with a vit D deficiency?

Answer 35

undermineralised and lacks rigidity

Question 36

what is the vitamin D deficiency bone disease in children?

Answer 36

rickets

Question 37

what is the vitamin D deficiency bone disease in adults?

Answer 37

osteomalacia

Question 38

why is calcitonin not essential for the regulation of plasma calcium?

Answer 38

because increased or decreased levels of calcitonin do not have any clinical consequences

Question 39

what is osteoporosis?

Answer 39

decreased bone mass and density

Question 40

what is osteopetrosis?

Answer 40

increased bone mass and density

Question 41

what can be seen in patients with osteoporosis?

Answer 41

fractures are common

Question 42

what category of people is osteoporosis common?

Answer 42

the elderly but affects women earlier than men because of menopause

Question 43

what are the causes of osteoporosis?

Answer 43

menopause, corticosteroids, nutritional deficiency

Question 44

what happens to blood supply in patients with osteopetrosis?

Answer 44

it is reduced

Question 45

what are the effects of osteopetrosis?

Answer 45

prone to fracture and chronic infection

Question 46

what are the dental consequences of osteopetrosis?

Answer 46

difficult extractions, tooth roots indistinct on radiographs, mandible is bigger than maxilla