Physiology 79: Pth, Calcitonin, Calcium And Phosphate, Vitamin D, Bone And Teeth

Front 1

Hypercalcemia has what effect on the nervous system?

Back 1

decreases nervous system (opposite from what we might expect)

Front 2

Hypocalcemia has what effect on the nervous system?

Back 2

increases nervous system (opposite from what we might expect). neuron membrane becomes more permeable to compensate and therefore is now more sensitive

Front 3

What is tetany?

Back 3

low calcium levels lead to repeated skeletal muscle contraction due to increased nervous activity

Front 4

Which vitamin is needed for calcium absorption in the GI tract?

Back 4

D

Front 5

Is calcium usually excreted in the urine?

Back 5

no, 99% is reabsorbed

Front 6

Bone is made up of what crystals?

Back 6

hydroxyapatite crystals (calcium and phosphate)

Front 7

Function of pyrophosphate

Back 7

prevent calcium and phosphate joining to form forming hydroxyapatite crystals in plasma

Front 8

Osteoblast function

Back 8

create collagen and ground substance to form bone

Front 9

Osteoclast function

Back 9

absorb bone to release calcium into the blood

Front 10

Stress on bones has what effect on remodeling?

Back 10

stress increases bone deposition by osteoblasts

Front 11

What is a callus?

Back 11

bulge of osteoblast tissue in response to fracture

Front 12

Where is cholecalciferol (vitamin D3) made?

Back 12

skin

Front 13

Cholecalciferol is 25-hydroxylated where?

Back 13

liver. now it is 25-hydrocholecalciferol

Front 14

25-hydrocholecalciferol is 1-hydroxylated where?

Back 14

kidney. now it is 1, 25- dihydroxy vitamin D (the most active form)

Front 15

What effect does PTH have on Vitamin D synthesis?

Back 15

PTH increases 1, 25 vitamin D synthesis to increase blood calcium levels

Front 16

How does calcium act as a negative feedback agent on its own absorption?

Back 16

high calcium inhibits PTH > less 1, 25 Vitamin D formation > less calcium binding protein/ATPase/alkaline phosphatase > less calcium absorption

Front 17

Low blood calcium will show (high or low) levels of Vitamin D as a response?

Back 17

as a response, vitamin D should be HIGH to try to raise blood calcium levels

Front 18

Vitamin D uses what type of receptor?

Back 18

retinoic X receptor (intracellular) that binds to hormone responsive element to up-regulate calcium binding protein transcription

Front 19

Vitamin D has what effect on calcium and phosphate in the urine?

Back 19

decreases kidney excretion of both calcium and phosphate

Front 20

A patient is seen to have tetany and a problem with their parathyroid gland. Is their parathyroid gland likely overactive or under-active?

Back 20

tetany = low blood calcium = low PTH to raise it

Front 21

PTH is secreted by what cells of the parathyroid gland?

Back 21

chief cells

Front 22

What type of hormone is PTH?

Back 22

peptide

Front 23

PTH causes a quick and then slow rise in calcium absorption into the blood form bone. What causes the first initial quick rise?

Back 23

activation of existing osteoclasts

Front 24

PTH causes a quick and then slow rise in calcium absorption into the blood form bone. What causes the second slow rise?

Back 24

proliferation and activation of new osteoclasts

Front 25

What is osteolysis?

Back 25

excess osteoclast activity degrading bones

Front 26

Vitamin D works to decrease calcium and phosphate loss in the urine. What does PTH do with regard to the kidneys?

Back 26

PTH decreases calcium excretion, but increases phosphate excretion

Front 27

PTH binds to what type of receptor?

Back 27

G protein (cAMP mechanism) usually

Front 28

WHat type of receptor is the Ca sensing receptor in the parathyroid gland?

Back 28

G protein (DAG, IP3 mechanism)

Front 29

Calcitonin function

Back 29

decrease blood calcium levels; lower osteoclast activity and formation

Front 30

Where is calcitonin made?

Back 30

C cells of the thyroid gland

Front 31

What is the first line of defense to regulate blood calcium levels?

Back 31

buffering via exchangeable calcium from bone

Front 32

What is the second line of defense to regulate blood calcium levels?

Back 32

hormonal intervention

Front 33

A patient has hypoparathyroidism. What do we expect his calcium levels to be?

Back 33

low PTH = less Vitamin D formation = less Ca absorption = low Ca

Front 34

A patient has hyperparathyroidism. What do we expect his calcium levels to be?

Back 34

high PTH = high vitamin D formation = high Calcium levels.absorption. also osteopenia form excess osteoclast activity

Front 35

Why do patients with osteopenia have elevated alkaline phosphatase levels?

Back 35

osteoblasts secrete ALP as they are trying to compensate for the osteopenia

Front 36

Kidney stones are likely in a patient with (hyper or hypo) parathyroidism?

Back 36

hyperparathyroidism = high Ca in blood = higher Ca in urine fluid = stones

Front 37

What is secondary hyperparathyroidism?

Back 37

high levels of PTH as a response to extremely low calcium in the blood

Front 38

What are Rickets?

Back 38

low calcium, PTH, VItamin D levels in children = bad bones, tetany

Front 39

What is osteomalacia?

Back 39

low calcium, PTH, VItamin D levels in adults = bad bones, tetany

Front 40

Why does kidney disease lead to osteomalacia?

Back 40

excess excretion of calcium = low blood calcium levels

Front 41

What is secondary hyperparathyroidism?

Back 41

high levels of PTH as a response to extremely low calcium in the blood

Front 42

What are Rickets?

Back 42

low calcium, PTH, VItamin D levels in children = bad bones, tetany

Front 43

What is osteomalacia?

Back 43

low calcium, PTH, VItamin D levels in adults = bad bones, tetany

Front 44

Why does kidney disease lead to osteomalacia?

Back 44

excess excretion of calcium = low blood calcium levels