Parathormone (PTH) is a hormone secreted by the parathyroid glands in response to low blood calcium levels. Its main function is to increase blood calcium levels by stimulating the release of calcium from bones, promoting calcium absorption from the intestines, and reducing calcium excretion by the kidneys.

Effect of Parathormone deficiency:
When there is a deficiency of parathormone, the blood calcium levels decrease, leading to a condition called hypocalcemia. This can cause muscle ramps or tetany, which is characterized by involuntary muscle contractions that can be painful and debilitating.

Explanation:
• Normally, calcium ions play a critical role in muscle contraction and relaxation.
• The concentration of calcium ions in the extracellular fluid surrounding the muscle fibers must be maintained within a narrow range for normal muscle function.
• When blood calcium levels are low, the concentration of calcium ions in the extracellular fluid also decreases, making it more difficult for the muscle fibers to contract and relax properly.
• This can lead to muscle ramps or tetany, which is characterized by involuntary muscle contractions that can be painful and debilitating.
• These muscle contractions can affect any muscle in the body, but they are most commonly seen in the hands and feet and can cause spasms and cramps that can be severe enough to interfere with daily activities.

Conclusion:
In conclusion, a deficiency of parathormone can lead to hypocalcemia, which can cause muscle ramps or tetany due to the decreased concentration of calcium ions in the extracellular fluid surrounding the muscle fibers.