Growth Hormone and its Effect on Growth

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Questions and Answers

How does Growth Hormone (GH) affect growth, and where is it synthesized?

GH affects growth by stimulating another endocrine gland. It is synthesized, stored, and secreted by somatotropic cells within the anterior pituitary gland.

Explain how both a deficiency and hypersecretion of insulin can affect growth.

A deficiency of insulin often blocks growth, while hyperinsulinism can spur excessive growth.

What roles do androgens play in growth, particularly during puberty?

Androgens play a role in the pubertal growth spurt and stimulate protein synthesis in many organs.

How does the liver metabolize Growth Hormone (GH) and how does this affect its duration of action?

The liver rapidly metabolizes GH, resulting in a short duration of action (20 minutes). Signup and view all the answers

How are the effects of androgens reliant on Growth Hormone?

The effects of androgens depend on the presence of GH. Signup and view all the answers

How does growth hormone (GH) exert most of its effects on target tissues?

GH exerts most of its effects indirectly by stimulating the production of insulin-like growth factors (IGF-1) in the liver and other tissues. Signup and view all the answers

What are the two main mechanisms by which growth hormone increases bone thickness?

Growth hormone increases bone thickness by stimulating cell reproduction and increasing the rate of mitosis, leading to hyperplasia. Signup and view all the answers

How does growth hormone affect fat metabolism, and why is this significant?

Growth hormone encourages the use of fats for fuel. This is significant because it helps spare glucose for use by the brain and other glucose-dependent tissues, while providing energy from fat stores. Signup and view all the answers

In what way does growth hormone function as an 'anti-insulin' hormone?

Growth hormone functions as an 'anti-insulin' hormone because it opposes insulin's effects on carbohydrate metabolism. Signup and view all the answers

How does the production of insulin-like growth factor 1 (IGF-1) relate to the skeletal effects of growth hormone?

The skeletal effects of growth hormone, such as increased bone thickness, are largely mediated indirectly by IGF-1. Signup and view all the answers

Describe how growth hormone facilitates the availability of glucose during periods of growth, considering its effects on both fat and carbohydrate metabolism.

Growth hormone promotes the use of fats for fuel (sparing glucose) and has anti-insulin effects on carbohydrate metabolism, ensuring glucose is available for cells that need it most. Signup and view all the answers

Explain the role of hyperplasia in the context of growth hormone's stimulation of cell reproduction.

Hyperplasia, which is an increase in cell number and proliferation rate, is stimulated by growth hormone and is a key factor in the growth of multiple body tissues. Signup and view all the answers

Why is understanding the indirect effects of growth hormone, specifically through IGF-1, important in treating growth disorders?

Understanding the indirect effects of growth hormone, specifically via IGF-1, is important because IGF-1 mediates most of GH's growth-promoting actions. Signup and view all the answers

Explain how growth hormone (GH) uses both direct and indirect actions to achieve its overall effect on the body.

GH directly stimulates metabolic changes like increased fat breakdown, while indirectly it stimulates the liver to produce growth factors that promote bone and muscle growth. Signup and view all the answers

Why is the regulation of Growth Hormone (GH) secretion more complex, involving both GHRH and GHIH, rather than just a single releasing hormone?

The dual regulation allows for precise control. GHRH stimulates GH release when growth is needed, while GHIH inhibits GH release to prevent overstimulation and maintain homeostasis. Signup and view all the answers

How does the feedback mechanism involving GH affect the release of GHRH and Somatostatin (GHIH) from the Hypothalamus?

Elevated levels of GH inhibit GHRH release and stimulate Somatostatin (GHIH) release. This negative feedback loop helps to regulate GH secretion and prevent excessive growth. Signup and view all the answers

Describe the difference between hypertrophy and hyperplasia, and indicate which of these processes is stimulated by Growth Hormone (GH).

Hypertrophy is an increase in cell size, while hyperplasia is an increase in cell number. GH primarily stimulates hypertrophy, leading to increased tissue mass. Signup and view all the answers

Which cells secrete growth hormone?

Somatotrophs. Signup and view all the answers

If a person has a tumor in their anterior pituitary, causing it to secrete excess growth hormone, describe a possible effect of this pathology.

Excess GH secretion can lead to gigantism in children, characterized by excessive bone growth, or acromegaly in adults, leading to thickened bones, enlarged organs, and other metabolic disturbances. Signup and view all the answers

A scientist is studying the effects of GH on muscle cells in vitro. Describe an experiment they could perform to assess the direct effects of GH on these cells.

The scientist could expose muscle cells to GH in a controlled environment and measure changes in protein synthesis or glucose uptake. This would isolate GH's direct actions on muscle metabolism. Signup and view all the answers

How does growth differ in children with growth hormone deficiency, compared to the growth of healthy children?

Children with GH deficiency exhibit slower growth rates, resulting in shorter stature compared to healthy children. Signup and view all the answers

How do the direct actions of growth hormone on adipocytes contribute to overall energy balance in the body?

GH promotes lipolysis in adipocytes, releasing fatty acids into the bloodstream. This provides an alternative energy source for tissues, helping to maintain blood glucose levels and support growth. Signup and view all the answers

Briefly describe a situation where administering a somatostatin analog may be therapeutically beneficial.

A somatostatin analog may be used to treat acromegaly, a condition caused by excessive growth hormone secretion, by inhibiting GH release from the pituitary gland. Signup and view all the answers

Explain how elevated levels of IGF-1 contribute to the regulation of Growth Hormone (GH) secretion.

High levels of IGF-1 stimulate the release of somatostatin (GHIH), which inhibits the secretion of Growth Hormone (GH). This is a negative feedback loop. Signup and view all the answers

Differentiate between primary and secondary hypersecretion of Growth Hormone (GH).

Primary hypersecretion results from abnormalities within the pituitary gland itself causing excess GH secretion. Secondary hypersecretion is caused by excessive stimulation from outside the pituitary gland. Signup and view all the answers

How do the effects of Growth Hormone (GH) deficiency differ between childhood and adulthood?

In childhood, GH deficiency leads to dwarfism, characterized by stunted growth. In adulthood, it results in loss of muscle and bone strength, cognitive changes affecting memory and reading, and affective changes influencing mood and attitudes. Signup and view all the answers

Compare and contrast gigantism and acromegaly in terms of their causes and the populations they affect.

Both gigantism and acromegaly are caused by GH excess. Gigantism occurs in childhood, affecting all body tissues and causing rapid growth, while acromegaly occurs in adulthood. Signup and view all the answers

Describe the role of tumors in the hypersecretion of Growth Hormone (GH).

Tumors, specifically in the pituitary gland, can ignore normal regulatory inputs and continuously secrete excess GH, leading to hypersecretion and conditions like gigantism or acromegaly. Signup and view all the answers

How does Growth Hormone (GH) contribute to increased bone length, and through what specific mechanism does this occur in young individuals?

GH promotes bone length increase by stimulating chondrogenesis at the epiphyseal plates before their union. Signup and view all the answers

Describe the dual roles of Growth Hormone (GH) in glucose metabolism, noting its acute and chronic effects on blood glucose levels.

GH acutely elevates blood glucose by reducing glucose uptake in cells and promoting hepatic glucose output. Chronically, this can cause increased insulin output and potentially beta cell burnout. Signup and view all the answers

Explain how Growth Hormone (GH) influences fat metabolism, and what condition can result from an excess quantity of this hormone?

GH increases fat breakdown and the mobilization of fatty acids for energy. An excessive amount of GH can result in ketosis due to high levels of ketone bodies. Signup and view all the answers

What role does Insulin-like Growth Factor-1 (IGF-1) play in the growth-promoting actions of Growth Hormone(GH), and how does its duration of action compare action to that of GH?

IGF-1 mediates many of GH's growth-promoting actions in tissues and cartilage. IGF-1 has a prolonged duration of action of about 20 hours, compared to GH. Signup and view all the answers

Describe how Growth Hormone (GH) impacts protein synthesis, and why are insulin and carbohydrates necessary for this process to be effective?

GH promotes protein synthesis, but adequate insulin and carbohydrates are necessary for GH to be effective because they facilitate amino acid transport and provide energy. Signup and view all the answers

How does Growth Hormone (GH) inhibit glucose uptake in muscles, and what enzyme does it affect to achieve this?

GH inhibits glucose uptake in muscles by inhibiting the hexokinase enzyme, which is normally needed to stimulate glucose uptake. Signup and view all the answers

What is the 'diabetogenic effect' of Growth Hormone (GH), and how does it manifest in terms of blood glucose and insulin levels?

The diabetogenic effect refers to GH's ability to increase blood glucose levels while simultaneously increasing insulin output to compensate. Signup and view all the answers

Explain how Growth Hormone (GH) stimulates hepatic glucose output, and name the specific process involved in this stimulation.

GH stimulates hepatic glucose output by promoting glycogenolysis, the breakdown of glycogen into glucose in the liver. Signup and view all the answers

Describe the process of chondrogenesis in the context of Growth Hormone (GH) action, and highlight its importance for skeletal growth.

Chondrogenesis, stimulated by GH, is the formation of new cartilage. This is crucial for skeletal growth, particularly in the lengthening of bones before the epiphyses unite. Signup and view all the answers

How can the indirect actions of Growth Hormone (GH) be characterized, and what hormone primarily mediates these effects?

Indirect actions of GH are largely growth-promoting effects mediated by Insulin-like Growth Factor-1 (IGF-1), which is produced in the liver and other tissues in response to GH stimulation. Signup and view all the answers

How does growth hormone (GH) contribute to bone growth at the epiphyseal plate, and what is the consequence of GH's action on bone structure in adults after the epiphyseal plates have fused?

GH stimulates cartilage proliferation and widening of epiphyseal plates, leading to increased bone length. In adults, after the union of the epiphysis, GH increases bone thickness but not length. Signup and view all the answers

Describe the role of placental hormones in fetal growth compared to the role of growth hormone (GH).

Placental hormones primarily drive fetal growth. GH plays no role in fetal development. Signup and view all the answers

How does sleep, particularly at night, affect growth hormone (GH) secretion, and what implications does this have for individuals with irregular sleep patterns?

GH is released most during sleep, especially at night. Changing sleeping patterns can affect GH release. Signup and view all the answers

Explain how a protein-rich diet and hypoglycemia stimulate growth hormone (GH) secretion.

A protein-rich diet increases amino acids in the blood, and hypoglycemia (low blood glucose) both stimulate GH secretion. Signup and view all the answers

Describe the negative feedback mechanism involving growth hormone (GH) and growth hormone-releasing hormone (GHRH).

High levels of GH inhibit GHRH secretion, which reduces further GH release. Signup and view all the answers

How do differing levels of glucose in the bloodstream affect the secretion of GH, and what are the specific terms for these conditions?

Hypoglycemia (low blood glucose) stimulates GH secretion, while hyperglycemia (high blood glucose) inhibits it. Signup and view all the answers

What is the effect of increased free fatty acids and excess cortisol on growth hormone (GH) secretion?

Increased free fatty acids and excess cortisol both inhibit GH secretion. Signup and view all the answers

Beyond its direct effects, how does ghrelin influence GH secretion, and what broader physiological role does this reflect?

Ghrelin, signaling hunger, stimulates GH secretion and increases appetite. Signup and view all the answers

How does the pattern of growth hormone (GH) secretion differ from that of other hormones, and what is the significance of this pattern?

GH is secreted in bursts, rather than continuously. This episodic release is often tied to sleep patterns and other physiological signals. Signup and view all the answers

Explain how age influences GH secretion and propose a reason for this change.

GH production declines with age. This decline is likely related to decreased metabolic needs and changes in body composition. Signup and view all the answers

Flashcards

What are somatic cells?

Body cells, excluding sperm and egg cells, which can be affected by endocrine gland activity.

What is Growth Hormone (GH)?

A hormone, made of amino acids in a single chain, that is synthesized, stored, and secreted by somatotropic cells in the anterior pituitary gland.