Chapter 17 - Section 17.2 - Study Guide - Assess Your Learning Outcomes - Page 669: 8

**Growth Hormone (GH):** Growth hormone (GH), also known as somatotropin, is a peptide hormone produced by the anterior pituitary gland. It plays a significant role in regulating growth, metabolism, and various physiological processes in the body. Here are some of the key actions of growth hormone: 1. **Stimulation of Growth:** GH is a primary regulator of growth during childhood and adolescence. It stimulates the growth of bones and tissues by promoting cell division and increasing the number and size of cells. 2. **Protein Synthesis:** GH enhances protein synthesis in various tissues, including muscles and bones. This contributes to the growth of lean body mass and overall development. 3. **Lipid Metabolism:** GH promotes the breakdown of fats (lipolysis) and their utilization as an energy source. This can lead to a reduction in body fat percentage. 4. **Blood Glucose Regulation:** GH has insulin-antagonistic effects, meaning it reduces the uptake of glucose by cells and stimulates the liver to produce glucose. This can lead to increased blood glucose levels. 5. **Stimulation of Insulin-like Growth Factors (IGFs):** One of the key mechanisms through which GH exerts its effects is by stimulating the production of insulin-like growth factors (IGFs), particularly IGF-1, in the liver and other tissues. **Insulin-like Growth Factors (IGFs):** Insulin-like growth factors (IGFs) are a family of proteins that play a crucial role in mediating the effects of growth hormone. The most important IGF is IGF-1. Here's how IGFs are involved in the effects of growth hormone: 1. **IGF-1 Production:** Upon stimulation by growth hormone, the liver releases IGF-1 into the bloodstream. IGF-1 production is also influenced by nutritional status, with higher levels during periods of adequate nutrition. 2. **Cellular Growth and Proliferation:** IGF-1 exerts its effects on target tissues by binding to IGF receptors on cell surfaces. It promotes cell growth, differentiation, and proliferation, particularly in bone and cartilage cells. 3. **Anabolic Effects:** IGF-1 enhances protein synthesis, which is essential for the growth and maintenance of muscle and other tissues. 4. **Anti-Apoptotic Effects:** IGF-1 helps prevent programmed cell death (apoptosis), contributing to the survival and maintenance of cells. 5. **Feedback Loop:** IGF-1, in turn, feeds back to the hypothalamus and pituitary gland to regulate the secretion of growth hormone. High levels of IGF-1 inhibit the release of growth hormone and, conversely, low levels stimulate its release. The interactions between growth hormone and insulin-like growth factors form a tightly regulated system that controls growth, metabolism, and homeostasis in the body. Dysregulation of this system can lead to growth disorders, such as gigantism (excessive growth) or dwarfism (insufficient growth), as well as other metabolic and physiological abnormalities.

**Growth Hormone (GH):** Growth hormone (GH), also known as somatotropin, is a peptide hormone produced by the anterior pituitary gland. It plays a significant role in regulating growth, metabolism, and various physiological processes in the body. Here are some of the key actions of growth hormone: 1. **Stimulation of Growth:** GH is a primary regulator of growth during childhood and adolescence. It stimulates the growth of bones and tissues by promoting cell division and increasing the number and size of cells. 2. **Protein Synthesis:** GH enhances protein synthesis in various tissues, including muscles and bones. This contributes to the growth of lean body mass and overall development. 3. **Lipid Metabolism:** GH promotes the breakdown of fats (lipolysis) and their utilization as an energy source. This can lead to a reduction in body fat percentage. 4. **Blood Glucose Regulation:** GH has insulin-antagonistic effects, meaning it reduces the uptake of glucose by cells and stimulates the liver to produce glucose. This can lead to increased blood glucose levels. 5. **Stimulation of Insulin-like Growth Factors (IGFs):** One of the key mechanisms through which GH exerts its effects is by stimulating the production of insulin-like growth factors (IGFs), particularly IGF-1, in the liver and other tissues. **Insulin-like Growth Factors (IGFs):** Insulin-like growth factors (IGFs) are a family of proteins that play a crucial role in mediating the effects of growth hormone. The most important IGF is IGF-1. Here's how IGFs are involved in the effects of growth hormone: 1. **IGF-1 Production:** Upon stimulation by growth hormone, the liver releases IGF-1 into the bloodstream. IGF-1 production is also influenced by nutritional status, with higher levels during periods of adequate nutrition. 2. **Cellular Growth and Proliferation:** IGF-1 exerts its effects on target tissues by binding to IGF receptors on cell surfaces. It promotes cell growth, differentiation, and proliferation, particularly in bone and cartilage cells. 3. **Anabolic Effects:** IGF-1 enhances protein synthesis, which is essential for the growth and maintenance of muscle and other tissues. 4. **Anti-Apoptotic Effects:** IGF-1 helps prevent programmed cell death (apoptosis), contributing to the survival and maintenance of cells. 5. **Feedback Loop:** IGF-1, in turn, feeds back to the hypothalamus and pituitary gland to regulate the secretion of growth hormone. High levels of IGF-1 inhibit the release of growth hormone and, conversely, low levels stimulate its release. The interactions between growth hormone and insulin-like growth factors form a tightly regulated system that controls growth, metabolism, and homeostasis in the body. Dysregulation of this system can lead to growth disorders, such as gigantism (excessive growth) or dwarfism (insufficient growth), as well as other metabolic and physiological abnormalities.