endocrine 5 - parathyroid Flashcards
where is parathormone PTH release
chief cells of the parathyroid gland
where is calcitonin relreased
parafollicular cells of thyroid (between thyroid follicles)
what do the chief cells of the parathyroid gland release
parathormone
what does PTH do to [calcium] in the ECF
increase
what does PTH do to [phosphate] in the ECF
decrease
is there more free ionized calcium in the ECF or ICF
more ECF (extracellularly)
how many kg of calcium is in our body
1kg
what % of calcium is in our bones
99%
what % of calcium is in other tissues than bones
1%
how many mg of calcium is free
500mg
what is resorption
bone breakdown into blood
what does calcitonin do to bones
reduces calcium levels in the blood to increase it in bone
what does PTH do to bones
increases calcium levels in the blood to decreases it in bone
what are 4 roles of calcium
structural
blood coagulation
intracellular messenger
regulation of excitability
what are 3 roles of phosphate
structural metabolism (ATP, nucleic acids) buffer (maintain pH balance)
when do you use phosphate as a buffer
when you deplete CO2 as a buffer
where is PTH released
parathyroid gland
where is calcitonin released
thyroid gland (parafollicular cells)
where is active vitamin D released
kidneys
what is the target of PTH
bone (kidney and GIT indirectly)
what is the target of active vitamin D
GI tract
what is the target of calcitonin
kidneys (bone and GIT indirectly)
what is the role of osteoblasts
bone deposition by adding Ca2+
what is the role of osteoclasts
bone resorption, release of Ca2+ from bone
what are the 3 catogories of structures in bone and their relative weights
organic stuff (1/3), inorganic salts(2/3), bone cells(negligible)
what is the organic framework for bone
collagen type 1
what is in the inorganic salt of bone
calcium phosphoate and hydroxyapatite
what are the bone cells
osteoblasts
osteocytes
oseoclasts
how are osteocytes made
they are osteoblasts that are in the bone that they made (mature osteoblasts)
what do osteoclasts look like
multi nucleated with ruffled borders, large, like a macrophage)
what do osteoclasts release to dissolve bone
enzymes and H+
when/why do osteoclasts start the cycle
with ruffled borders or slight damage/ rough edges
what do osteoblasts do once osteoclasts do resorption of the bone
they lay done and secrete proteins like collagen and osteoid
what is osteoid
the organic framework matrix of bone
what signals vitamin D release
raised plasma parathyroid hormone PTH
what happens with raised vitamin D
more calcium absorption into blood from the intestines
what happens to PTH with low calcium
raise levels of secretion
what kind of solubility is vitamine D
lipid soluble
how does PTH increase active Vit D
increases 1alphaHydroxylase
what does 1alphaHydroxylase do
adds OH to activate vitamin D
what does calbindin do
moves Ca from the luminal to the basolateral side
what is calbindin
protein that binds to Ca++ to allow its transportx
what are the 3 vitamin D regulated froteins
ECaC (lets Ca++ into cell)
calbindin protein
basolateral calcium pump
what kind of hormone is PTH
peptide
what kind of hormone is calcitonin
peptide
what does PTH do to blood phosphate
decrease (let it out in urine)
what does Vit D do to blood phosphate
increase
what does calcitonin do to blood phosphate
decrease
what causes secretion of PTH
decreased blood Ca++
what causes secretion of Vit D
PTH
what causes secretion of calcitonin
increased blood Ca++
what does PTH do to bone
increase resorption
what does Vit D do to bone
increase resorption by working with PTH
what does PTH do to kidney
increase reabsorption of Ca++
decrease reabsorption of phosphate
what does Vit D do to kidney
increase reabsorption of Ca++ and phosphate
what does Vit D do to GIT
increase reabsorption of Ca++ and phosphate (major)
what does PTH do to GIT
increase reabsorption of Ca++ and phosphate (indirect via Vit D)
what causes rickets
deficiency of Vit D in children
what causes osteomalacia
deficiency of Vit D in adults
what is osteomalacia
softening of the bones, typically through a deficiency of vitamin D in adults
what causes tetany
low calcium
what happens with low plasma calcium
increases nerve and muscle excitability via opening of Na+ channels
what would happen without parathyroid hormone
you die
