Question

Somatomedins are required for the anabolic effects of a. hydrocortisone. c. growth hormone. b. insulin. d. thyroxine.

Short answer

The substance that requires somatomedins for its anabolic effects is growth hormone (c). Somatomedins, or insulin-like growth factors, are crucial for mediating the anabolic actions of growth hormone, contributing to cell growth and development.

Step-by-step solution

Understand The Role of Somatomedins

Somatomedins, also known as insulin-like growth factors (IGFs), are peptides that play a crucial role in cell growth and development. They are produced primarily by the liver in response to growth hormone (GH) stimulation.

List The Effects of Given Substances

a. Hydrocortisone: It is a corticosteroid hormone that has anti-inflammatory and immunosuppressive effects. It is not linked to anabolic effects. b. Insulin: It is a hormone that regulates glucose levels in the bloodstream by facilitating glucose uptake into cells. Insulin has some anabolic effects, such as promoting protein synthesis in muscles. c. Growth hormone: It is a hormone that stimulates cell growth, regeneration, and reproduction. Growth hormone has an essential role in producing anabolic effects, such as increasing muscle mass and bone density. d. Thyroxine: It is a thyroid hormone that regulates metabolism and energy production in the body. It does not have a direct relation to anabolic effects.

Identify The Substance That Requires Somatomedins for Anabolic Effects

Based on the information gathered in Steps 1 and 2, it is clear that growth hormone (c) requires somatomedins for its anabolic effects. Somatomedins, such as insulin-like growth factors, mediate the anabolic actions of growth hormone and contribute to cell growth and development.

Key concepts

Insulin-like Growth Factors

Insulin-like growth factors (IGFs) are proteins with high sequence similarity to insulin. IGFs have a significant role in growth and development, especially during childhood and adolescence. These factors function as signaling molecules, telling cells to grow and multiply.

There are two primary IGFs in the human body – IGF-1 and IGF-2. IGF-1 is particularly important in the processes that lead to growth at the cellular level, acting as a mediator for growth hormone (GH) effects. When GH is released from the pituitary gland, it stimulates the liver to produce IGF-1. This, in turn, prompts various growth-related activities within the body's tissues, contributing to bone elongation and muscle development.

IGFs don't just work in isolation; they interact with their receptors on cell surfaces and with IGF-binding proteins, which modulate their actions. Understanding the complex interplay between IGFs, their receptors, and binding proteins is crucial for comprehending how our bodies grow and repair tissue.

Growth Hormone

Growth hormone (GH), also known as somatotropin, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. This hormone, produced by the pituitary gland, has both direct and indirect effects on the body.

Directly, GH can stimulate cell division in a variety of tissues. Indirectly, its growth-promoting effects are largely mediated by IGF-1 which, as previously mentioned, acts on various tissues to stimulate systemic body growth. GH also boosts protein production, promotes the utilization of fats, interferes with the action of insulin, and raises blood sugar levels. GH deficiency can lead to reduced muscle mass and bone density, while an excess can cause abnormal growth conditions.

Moreover, GH has a diurnal cycle, with secretion highest during sleep, which reflects its role in physiological processes. Its production is regulated by complex neuroendocrine mechanisms involving hormones called 'growth hormone-releasing hormone' (GHRH) and 'somatostatin' which are released by the hypothalamus.

Anabolic Effects

Anabolic effects in the body are those that contribute to the building up and repairing of tissues, particularly muscle and bone. This is in contrast to catabolic processes, which break down tissue and energy stores. Anabolic effects are mediated by certain hormones, such as testosterone, insulin, and growth hormone.

The anabolic effects of GH are especially pronounced; it stimulates the liver and other tissues to secrete IGF-1, which prompts increased protein synthesis and organ growth. This process plays a critical role in muscle and bone development during childhood, as well as helps maintain tissue health throughout life.

Anabolic effects are also essential in metabolism management, helping to regulate energy storage and consumption. For athletes and bodybuilders, these effects are desired as they contribute to muscle mass and strength increases. However, when anabolic hormones are used improperly, they can lead to an imbalance in normal physiological functions and have health risks.