Parathyroid Glands Flashcards
When there is a drop in blood calcium levels in cats, dogs and cows it is termed:
Eclampsia, Milk fever, Hypocalcemia, Puerpal Tetany
Spastic skeletal muscle contraction is :
Hypocalcemic tetany
The excitability of the muscles is due to which ion?
Ca, since it blocks Na channel activity
What hormone do Parathyroid glands secrete to raise Blood Ca level?
Parathyroid hormone (PTH)
Blood coagulation, Secretion, Cell function, Neuronal transmission and muscle contraction all need:
calcium
What 3 hormones regulate blood calcium level?
- PTH
- Active vitamin D3
- Calcitonin
What produces and secretes PTH?
Chief cells in PT glands
What is the precursor in chief cells for PTH?
Pre-proPTH
How many AA does PTH have?
34
When do chief cells in the PT glands become active?
When there is a low blood calcium
T/F PTH raises blood calcium and PROMOTES Calcium phosphate deposition in bone
False, it does not promote the deposition
Other than decreased blood calcium level, what other thing can stimulate PTH secretion?
Increase in PO4 3-
What part of the bone is stimulated by PTH to promote resorption and release the Ca?
Osteoclasts
What organ is stimulated by the PTH to reabsorb Ca ?
Kidneys
PTH will help the kidney convert _______________ into active form to indirectly raise blood Ca?
Vitamin D3
Where does 1, 25-dihydroxyvitamin D3 production begin?
Skin
Vitamin D3 precursor is:
7-dehydrocholesterol
Where is Vit D3 converted to the active 1,25 (OH)2 D3?
Liver and kidney
In the liver, the hydroxyl group is added to which C in vitamin D3?
25
In the kidney, the hydroxyl group is added to which C in vitamin D3?
1
What type of enzyme in the kidney is stimulated by PTH that helps to activate vit D3?
Hydroxylation enzyme
Absorption of Ca and PO4 3 is promoted by activated Vit D3 in the ____________________
small intestine
_________________ of Ca happens in the kidneys
reabsorption
Increases Ca and PO4 3- results in a _______________ (increase or decreased) tendency to precipitate as bone crystals
increased
Where are the PTH receptors in the bone?
OsteoBLASTS
What is produced when PTH stimulates osteoblasts?
RANKL (receptor activator of nuclear factor K B ligand)
RANKL bind to __________ on preosteoclast to mature it and begin resorption
RANK
Cancers will secrete the hormone _______________ to mimic the role of PTH
PTH-related protein (PTHrP)
What does the PTHrP cause in relation to the increase in bone resorption?
Hypercalcemia
In malignancy-related hypercalcemia (pseudo-hyperparathyroidism), PTH levels are _____________
normal or low
PTHrP levels in pseudo-hyperparathyroidism are ?
high in 80%
A high level of PTH in blood is termed:
hyperparathyroidism
Primary hyperparathyroidism can be caused by:
Parathyroid tumor or cancer
Hypercalcemia in primary hyperparathyroidism can lead to ?
Kidney stones
Secondary hyperparathyroidism occurs through what feedback?
Ca negative feedback
What is an example of Secondary hyperparathyroidism?
Rickets / Osteomalacia
Secondary hyperparathyroidism is linked to hyper or hypocalcemia?
Hypocalcemia
Hyperparathyroidism is linked to kidney stones and what other sign?
Osteoporosis
Low level of PTH is called:
Hypoparathyroidism
What can cause Hypoparathyroidism?
cancer radiation tx
injury to parathyroid glands
- muscle aches/cramps
- muscle spasms (especially around mouth)
- tingling, burning, numbness in fingertips, toes, lips
- seizures
- osteoporosis
Symptoms of Hypoparathyroidism
Thyroid parafollicular cells will produce ____________ in response to increased blood ca/
Calcitonin
The counterregulatory hormone to PTH is
Calcitonin
Calcitonin will do what to osteoclastic activity?
Inhibit it and thus bone resorption
What can be use to tx hypercalcemia, osteoporosis, and Paget’s disease?
salmon calcitonin
Paget’s disease is ?
Excessive bone remodeling caused by increased osteoclastic actvity
A decrease in Ca/increase in phosphate will lead to ___________ secretion from PT glands
PTH
PTH secretion will increase ________________ in the kidneys
Ca reabsorption
An Increase in Ca will stimulate the _________________ to secrete Calcitonin
Thyroid glands
