<span>Parathyroid Hormone (PTH) is a hormone that signals an increase in blood calcium (Ca2+) within into the bloodstream when below normal ranges. When blood calcium is within normal ranges Calcitonin is released from the thyroid to stop blood calcium from increasing thus maintaining equilibrium.</span>
hope this helps
I do think that they close to not allow too much of either water or air from entering.
the hollow tube allows water to flow easily.
https://www.bbc.co.uk/bitesize/guides/z28g7p3/revision/1
The myelin sheath covers most of the axon. It is important because it helps to protect the axon and speed up the neuron firing process by decreasing the amount of time in the axon.
I'd say an <span>endocrinologist would be the best answer.</span>
I think it’s B
I hope this is helpful
