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Unit 4.6 - Coggle Diagram
Unit 4.6
Vitamin D
group of sterols produced by effect of UV and enzymes on various precursors
exerts hormones - like actions on target cells
can be obtained from food
produced in skin by effect of UV rays of sun
mediates calcium absorption from intestine
facilitates calcium and phosphorus reabsorption by kidney tubules
deficiency leads to deficiency of calcium in bones
functions:
increases calcium absorption from intestine
facilitates calcium & phosphorus reabsorption by kidney tubules
promotes absorption of calcium resulting in bone growth and remodelling
calcitonin
polypeptide
thyrocalcitonin
plays important role in calcification of bones
calcitonin lowers calcium levels in blood
antagonist to PTH
secretion is stimulated by high plasma calcium levels
function:
lowers calcium levels by:
calcification of bones: stimulates osteoblasts & inhibits osteoclast activity
increasing urinary excretion of Ca+
preventing intestinal absorption of Ca+
thyroid gland
largest endocrine gland
2 lobes
secretes 3 hormones
thyroxine / tetraiodothyronine (T4)
triiodothyronine (T3)
calcitonin
calcitonin
produced by C-cells of thyroid
plays an important role in calcium metabolism