Question

Which of the following pairs of hormones are involved in the regulation of blood \(\mathrm{Ca}^{2+}\) concentration in vertebrates? a. aldosterone and ANP b. insulin and glucagon c. parathyroid hormone and 1,25 -dihydroxyvitamin \(D\). d. prolactin and oxytocin e. thyroxine and TSH

Short answer

The pair of hormones that regulate blood \(\mathrm{Ca}^{2+}\) concentration in vertebrates are 'c. parathyroid hormone and 1,25 -dihydroxyvitamin D'.

Step-by-step solution

Hormones Analysis

Hormones are produced by various glands in the body and have specific functions. Aldosterone and ANP regulate salt balance. Insulin and glucagon are involved in the metabolism of sugars. Thyroxine and TSH regulate metabolic rate. Prolactin and oxytocin play roles in reproduction.

Identification

Parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D are the two hormones that help to maintain calcium homeostasis in the body. PTH increases blood calcium levels by promoting bone resorption (the breakdown of bone) and reducing loss of calcium in urine. On the other hand, 1,25-dihydroxyvitamin D increases blood calcium levels mainly by increasing the absorption of calcium from food in the intestines.

Conclusion

Upon conducting hormone by hormone analysis and identifying their specific roles, we find our answer to be 'c. parathyroid hormone and 1,25 -dihydroxyvitamin D'.

Key concepts

Parathyroid Hormone

The parathyroid hormone (PTH) plays a crucial role in regulating calcium levels in vertebrates. It is produced by the parathyroid glands, which are small glands located behind the thyroid gland in the neck. PTH helps raise calcium levels in the blood, crucial for maintaining healthy nerve and muscle function.
One of the ways PTH increases blood calcium is by stimulating bone resorption. This process involves breaking down bone tissue and releasing calcium into the bloodstream. But, it's not all about the bones. PTH also signals the kidneys to reduce the amount of calcium excreted in urine, conserving more calcium for the body.
Additionally, PTH indirectly promotes intestinal calcium absorption by stimulating the production of 1,25-dihydroxyvitamin D in the kidneys. This collaborative effort ensures that calcium balance is maintained even when dietary intake varies.

1,25-Dihydroxyvitamin D

1,25-Dihydroxyvitamin D, often referred to as calcitriol, is the active form of vitamin D in the body. It holds a central role in calcium homeostasis by facilitating the absorption of calcium from the diet through the intestines.
Calcitriol is synthesized in the kidneys from its precursor forms in response to PTH. When blood calcium levels drop, PTH is released, triggering the conversion of vitamin D into its active form. This adjustment helps ensure that sufficient calcium is absorbed from food.
By boosting intestinal absorption of calcium, calcitriol supports bone health alongside PTH and helps prevent disorders like rickets in children and osteomalacia in adults, both of which are conditions caused by inadequate bone mineralization. Together with PTH, calcitriol adapts the body's mechanisms to maintain stable calcium levels.

Vertebrate Physiology

Vertebrate physiology encompasses the study of how systems of the body work together in organisms with spines, including humans and other animals. Calcium homeostasis is a perfect example of such collaboration among systems.
Calcium is vital for many biochemical processes, including muscle contraction, nerve transmission, and blood clotting. To maintain these essential functions, the body orchestrates a complex system involving hormones like PTH and calcitriol to manage calcium levels.
Understanding vertebrate physiology helps us appreciate how the endocrine, skeletal, and digestive systems work in unison to regulate calcium. This ensures that calcium levels remain within a narrow range, protecting overall bodily health. Learning about these processes highlights the adaptive nature of physiological systems in managing resources efficiently amid changing environmental conditions.