Question

Assertion: In parathyroid tetany rapid spasm of muscle occurs. Reason: It is due to low calcium ion in body fluid.

Short answer

Yes, the assertion and reason are correct. In parathyroid tetany, due to an underactive parathyroid gland, there's a low calcium ion concentration in the body fluid which disrupts the normal muscle function causing rapid muscle spasms.

Step-by-step solution

Understanding Parathyroid Tetany

Parathyroid tetany is a medical condition characterized by muscle spasms, and it is caused by an underactivity of the parathyroid glands, which are small glands located in the neck. These glands are responsible for regulating calcium levels in the body through the production of parathyroid hormone (PTH). PTH increases the concentration of calcium in the blood.

Role of Calcium Ions in Muscle Contractions

Calcium ions play a crucial role in the contraction of muscles. It initiates a process called excitation-contraction coupling, whereby an electrical impulse from a nerve triggers the release of calcium ions in the muscle cells. These ions then bind to proteins within the muscle fibers, causing them to shorten and produce a contraction.

Effect of Low Calcium Ions Concentration

When there is low concentration of calcium ions in body fluid, the normal process of muscle contraction and relaxation is disrupted. This is because there isn't enough calcium for normal muscle function. This causes the muscles to contract rapidly and uncontrollably, leading to spasms and cramps, which are symptoms of parathyroid tetany.

Key concepts

Muscle Contraction

Muscle contraction is a fascinating and complex process that allows our bodies to move. At its core, muscle contraction happens when the muscle fibers shorten and tighten. The process begins with an electrical signal from a nerve that reaches the muscle.
This signal is necessary to start a chain of events called excitation-contraction coupling.

• First, the electrical impulse causes calcium ions to be released in the muscle cells.
• Then, these calcium ions attach to specific proteins within the muscle fibers.
• This attachment triggers a change in the shape of the proteins, allowing the muscle fibers to overlap more closely and shorten.

Without this carefully orchestrated sequence, muscles would not be able to contract properly, highlighting how crucial calcium is in this entire process.

Calcium Regulation

Calcium regulation in the body is a critical process, ensuring that the levels of calcium ions in body fluids are maintained within a suitable range.
This regulation is vital because calcium plays numerous roles, not only in muscle contraction but also in maintaining healthy nerve function and bone strength.

• When calcium levels drop, this can lead to disturbances in muscle function, commonly referred to as muscle spasms or cramps.
• Such conditions are often termed as parathyroid tetany, where the low calcium levels cause involuntary muscle contractions.
• Conversely, excess calcium can lead to other issues, such as forming kidney stones.

The body's ability to regulate calcium depends heavily on several hormones and cellular processes, ensuring balance for optimal function.

Parathyroid Hormone

The parathyroid hormone (PTH) is an essential component of calcium metabolism. It's produced by the parathyroid glands, which are tiny glands located in the neck, and plays a pivotal role in maintaining calcium homeostasis.
When calcium levels in the blood dip too low, the parathyroid glands secrete more PTH. This hormone acts by:

• Encouraging the release of calcium from bones into the bloodstream.
• Enhancing the kidney's reabsorption of calcium, reducing its excretion.
• Stimulating the conversion of vitamin D to its active form, which increases the absorption of calcium from the gut.

By these actions, PTH helps to keep calcium levels stable, ensuring proper functioning of muscles and nerves. When PTH is deficient or in excess, it can lead to conditions like parathyroid tetany or hypercalcemia, impacting muscle contractions and overall health.