Hypothalamus and Pituitary Hormones Overview
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Questions and Answers

What stimulates the synthesis of growth hormone (GH)?

  • Cortisol
  • Insulin
  • Thyroid hormone
  • Growth hormone-releasing hormone (GHRH) (correct)

    • The absence of thyroid hormone can lead to increased growth in children.

    False

    What is the role of IGF-1 in GH secretion?

    Primary negative feedback regulator

    Incretin, specifically ______, is a known stimulator of GH secretion.

    <p>Ghrelin</p> Signup and view all the answers

    Which factor is NOT a stimulatory factor for GH secretion?

    <p>Hyperglycemia</p> Signup and view all the answers

    How do GH levels differ between children and adults?

    <p>GH levels are higher in children than in adults.</p> Signup and view all the answers

    Match the hormone to its function:

    <p>GHRH = Stimulates GH synthesis Ghrelin = Stimulates GH secretion IGF-1 = Negative feedback regulator of GH Thyroid hormone = Required for normal GH formation</p> Signup and view all the answers

    Adults stop producing GH as they age.

    <p>False</p> Signup and view all the answers

    What is one of the primary actions of growth hormone (GH) regarding bones?

    <p>Stimulates osteoblast activity</p> Signup and view all the answers

    Growth hormone directly promotes fat storage in adipose tissue.

    <p>False</p> Signup and view all the answers

    Name the factors released by the liver in response to growth hormone that aid in growth.

    <p>somatomedin</p> Signup and view all the answers

    Growth hormone enhances ___ synthesis, leading to increased muscle mass.

    <p>protein</p> Signup and view all the answers

    Match the following effects with their corresponding target tissues:

    <p>Adipose Tissue = Promotes lipolysis Bone = Stimulates osteoblast activity Muscle = Enhances protein synthesis Liver = Releases somatomedin in response to GH</p> Signup and view all the answers

    Which of the following statements about the linear growth effects of growth hormone is correct?

    <p>It promotes chondrocyte proliferation at the growth plate.</p> Signup and view all the answers

    Growth hormone decreases glucose utilization in most tissues.

    <p>True</p> Signup and view all the answers

    What role does the liver play in growth hormone-mediated growth?

    <p>Releases somatomedin</p> Signup and view all the answers

    Which condition is characterized by a lack of growth hormone during childhood?

    <p>Pituitary dwarfism</p> Signup and view all the answers

    Laron dwarfism results from a lack of growth hormone receptors.

    <p>True</p> Signup and view all the answers

    What is the primary effect of growth hormone during fasting?

    <p>Mobilizes fat while sparing glucose and protein</p> Signup and view all the answers

    Gigantism is characterized by overproduction of GH during __________.

    <p>childhood</p> Signup and view all the answers

    Which of the following statements best describes acromegaly?

    <p>It occurs due to overproduction of GH in adulthood.</p> Signup and view all the answers

    Match the conditions with their causes:

    <p>Pituitary dwarfism = GH deficiency during childhood Laron dwarfism = GH receptor issue Gigantism = Overproduction of GH during childhood Acromegaly = Overproduction of GH in adulthood</p> Signup and view all the answers

    What percentage of genetic growth potential is influenced by growth hormone?

    <p>30%</p> Signup and view all the answers

    What role do somatomedin play in response to GH?

    <p>They are released from various cells, including those in bone.</p> Signup and view all the answers

    In the fed state, GH and IGF-1 promote anabolic growth.

    <p>True</p> Signup and view all the answers

    What hormone is secreted by lactotropes in the anterior pituitary?

    <p>Prolactin</p> Signup and view all the answers

    Lactotropes are part of an endocrine axis.

    <p>False</p> Signup and view all the answers

    What happens to prolactin secretion if the pituitary stalk is compromised?

    <p>Prolactin secretion increases.</p> Signup and view all the answers

    Prolactin secretion is regulated by a __________ feedback loop.

    <p>neuro-endocrine</p> Signup and view all the answers

    What is the role of oxytocin in lactation?

    <p>Ejecting milk from the mammary gland</p> Signup and view all the answers

    Nursing should be initiated immediately to maintain exposure to low levels of prolactin.

    <p>False</p> Signup and view all the answers

    What is required for the production of milk in the mature mammary gland?

    <p>Continued stimulation by prolactin.</p> Signup and view all the answers

    Match the following terms with their relevant functions in lactation:

    <p>Prolactin = Synthesis and secretion of milk Oxytocin = Ejection of milk Nursing = Maintaining exposure to prolactin Pituitary stalk compromise = Increased prolactin secretion</p> Signup and view all the answers

    Study Notes

    Hypothalamus and Pituitary Hormones

    • Hypothalamus releases GnRH, TRH, CRH, GHRH, SRIF, and Dopamine, which stimulate the pituitary.
    • Pituitary releases LH, FSH, TSH, ACTH, GH, and PRL.
    • These hormones regulate various end organs like testis, ovaries, thyroid, adrenal, and breast tissues influencing gametogenesis, hormone production, and metabolism.

    Growth Hormone (GH)

    • Stimulation: Growth hormone-releasing hormone (GHRH) from the hypothalamus stimulates GH synthesis.
    • Requirement for formation: Thyroid hormone is essential for normal GH amounts.
    • Absence of thyroid hormone: Causes cretinism marked by short stature.
    • GH half-life: The duration of GH in the bloodstream.

    IGF-1 and Ghrelin

    • Ghrelin: A gut hormone, is a stimulator of GH secretion, though its precise role isn't fully understood.
    • IGF-1: A primary negative feedback regulator of GH, with a longer half-life.

    GH Secretion Factors

    • Stimulatory factors: Stress, hypoglycemia, amino acids (e.g., arginine), and traumatic/psychogenic stress.

    GH Secretion Activity

    • Multiple episodes: GH is secreted in multiple bursts, most notably during the early hours of sleep.
    • Diurnal rhythm: GH secretion follows an approximate daily pattern.
    • Persistent secretion: Secretion continues throughout life, even after growth ceases.
    • Differences in children and adults: GH levels are higher in children compared to adults, peaking during puberty.
    • Aging effect: GH secretion declines with age.

    GH Secretion and Aging

    • Adults producing GH: Yes, because of the role of GH in metabolism.
    • Effect of senescence: GH levels fall during senescence.

    Growth Hormone Actions

    • Growth: Promotes long bone growth (stature).
    • Metabolic effects:
      • Stimulates insulin-like growth factors (IGFs).
      • Enhances lean body mass by promoting protein synthesis and fat utilization.

    Target Tissue Response to GH

    • Bone metabolism: Stimulates osteoblast activity, promoting bone formation and remodeling; encourages linear growth by stimulating chondrocyte proliferation at the epiphyseal plate.
    • Adipose tissue: Promotes lipolysis (fat breakdown), reducing fat stores, and increasing free fatty acid availability for energy.
    • Muscle: Enhances protein synthesis, increasing muscle mass and strength.

    Extending Bone Growth

    • GH stimulates IGF production, which directly stimulates chondrocyte (cartilage cells) proliferation and activity within the growth plate of long bones.

    Role of Liver in GH-Mediated Growth

    • The liver is a target organ for GH and releases somatomedin in response to GH.

    Other Cell Types in GH-Mediated Growth

    • Besides the liver, other cell types, such as bone cells, also release somatomedins in response to GH.

    Pituitary Dwarfism

    • Results from a deficiency in GH production during childhood.

    Laron Dwarfism

    • A lack of response to GH due to a receptor issue; different from pituitary dwarfism because of the lack of response to GH.

    Gigantism

    • Results from the overproduction of GH during childhood leading to a very tall stature

    Acromegaly

    • Overproduction of GH in adulthood, leading to enlarged bones and soft tissues. It's different from gigantism, which arises during childhood.

    Metabolic Actions of GH- Fed vs Fasting

    • Fed state: GH is anabolic, promoting protein synthesis, cell growth, and tissue repair.
    • Fasting state: GH is catabolic, mobilizing energy through lipolysis and decreasing glucose uptake.

    Metabolic Effects of GH (fasting/fed)

    • During fed states, GH and IGF-1 promote anabolic growth.
    • During fasting states, GH mobilizes fats and conserves protein.

    Prolactin

    • Secretion: Produced by lactotropes in the anterior pituitary.
    • Role in lactation: Stimulates milk synthesis and secretion.
    • Regulation: A neuroendocrine feedback loop; hypothalamus inhibits prolactin secretion, but the pituitary stalk's compromise leads to prolactin increase.
    • Oxytocin's role: Ejection of milk from the mammary gland.
    • Estrogen impact: Estrogen enhances prolactin secretion.
    • Mammary gland function and pregnancy: Plays a role in the arrangement of the epithelial cells from the basement membrane and cell types.
    • Nursing initiation: Stimulating nursing after the loss of pregnancy hormones promotes lactation.

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    Description

    This quiz explores the roles of hypothalamus and pituitary hormones in regulating various body functions. It covers hormones such as GnRH, GHRH, and GH, along with their impacts on growth and metabolism. Test your understanding of these key endocrine processes!

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