Growth Hormone Overview
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Questions and Answers

What is the primary action of growth hormone on protein metabolism?

  • Increases the synthesis of proteins (correct)
  • Decreases amino acid transport through cell membrane
  • Increases the breakdown of ribonucleic acid
  • Increases the catabolism of proteins

    • Which of the following is NOT a physiological effect of growth hormone?

  • Conservation of glucose
  • Mobilization of fats from adipose tissue
  • Decreased protein anabolism (correct)
  • Increased amino acid transport

    • What is the molecular weight of growth hormone?

  • 30,000
  • 18,000
  • 15,200
  • 21,500 (correct)

    • How does growth hormone affect carbohydrate metabolism?

    <p>Stimulates glycogen deposition in cells</p> Signup and view all the answers

    What is the normal basal concentration of growth hormone in adult humans?

    <p>3 ng/mL</p> Signup and view all the answers

    Which hormone is released due to the action of growth hormone, contributing to its anabolic effect?

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

    What is the estimated half-life of circulating growth hormone?

    <p>20 minutes</p> Signup and view all the answers

    What metabolic condition can occur as a result of excessive growth hormone levels?

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

    What specific facial feature is characteristic of acromegaly, often described as a 'gorilla face'?

    <p>Protrusion of supraorbital ridges</p> Signup and view all the answers

    What is the role of somatomedin in the action of growth hormone?

    <p>It is a substance through which growth hormone acts.</p> Signup and view all the answers

    Which hormone negatively inhibits GHRH-mediated GH release from the anterior pituitary?

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

    What is the most common cause of hyposecretion of GH leading to dwarfism?

    <p>Tumor of chromophobes</p> Signup and view all the answers

    Which of the following is NOT an effect of growth hormone on bones?

    <p>Decreasing the thickness of membranous bones.</p> Signup and view all the answers

    What condition might accompany acromegaly due to excess GH secretion?

    <p>Carpal tunnel syndrome</p> Signup and view all the answers

    After the epiphyseal fusion, what aspect of bone growth remains influenced by growth hormone?

    <p>The thickness of the bones.</p> Signup and view all the answers

    How long does the action of somatomedin C last in the body?

    <p>20 hours</p> Signup and view all the answers

    What is the primary role of somatomedin in relation to growth hormone?

    <p>Mediates the actions of GH</p> Signup and view all the answers

    What is a common symptom of dwarfism associated with other anterior pituitary hormone deficiencies?

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

    What is an expected adult height for someone with anterior pituitary dwarfism?

    <p>Approximately 3 feet</p> Signup and view all the answers

    Which of the following correctly describes the effect of growth hormone on muscle mass?

    <p>It stimulates muscle mass through hypertrophy of sarcomeres.</p> Signup and view all the answers

    Which factor does NOT stimulate the secretion of growth hormone?

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

    What treatment option is commonly used for GH-producing tumors in acromegaly?

    <p>Surgical removal</p> Signup and view all the answers

    What hormone is responsible for decreasing growth hormone secretion?

    <p>Growth hormone-inhibitory hormone (GHIH)</p> Signup and view all the answers

    What is one important role of insulin-like growth factor-II?

    <p>Promoting growth during fetal development.</p> Signup and view all the answers

    Which of the following organs may enlarge as a result of acromegaly?

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

    Which process is enhanced by growth hormone in relation to calcium?

    <p>Increased calcium absorption through the intestine.</p> Signup and view all the answers

    During which stages of sleep does the majority of growth hormone secretion occur?

    <p>Third and fourth NREM sleep stages</p> Signup and view all the answers

    Which of the following statements is true regarding the hypothalamus's role in GH secretion?

    <p>It utilizes hypothalamo hypophyseal portal blood vessels for hormone transport</p> Signup and view all the answers

    What happens to blood glucose levels as a result of GH hypersecretion?

    <p>They increase tremendously.</p> Signup and view all the answers

    Which physiological condition is likely caused by hypersecretion of growth hormone during childhood?

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

    What is the main effect of elevated free fatty acids in the blood on growth hormone secretion?

    <p>Inhibits GH secretion</p> Signup and view all the answers

    What does the growth hormone receptor primarily stimulate in relation to the liver?

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

    What happens to the head in relation to the body in cases of growth hormone deficiency?

    <p>The head becomes slightly larger in relation to the body.</p> Signup and view all the answers

    What is primarily affected by growth hormone (GH) deficiency?

    <p>Overall body size and development.</p> Signup and view all the answers

    Which diagnostic test is typically the final step in diagnosing GH deficiency?

    <p>GH stimulation tests.</p> Signup and view all the answers

    What endocrine dysfunction occurs with pituitary insufficiency?

    <p>Atrophy of the adrenal cortex and sensitive stress response.</p> Signup and view all the answers

    Which of the following hormones is regulated by factors affecting growth hormone secretion?

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

    What is the mode of secretion for growth hormone?

    <p>Episodic and influenced by hypothalamic factors.</p> Signup and view all the answers

    What is mainly affected by overproduction or underproduction of growth hormone?

    <p>Height and muscle mass during puberty.</p> Signup and view all the answers

    Which part of the pituitary gland secretes primarily tropic hormones?

    <p>Anterior lobe.</p> Signup and view all the answers

    Study Notes

    Growth Hormone (GH)

    • Secreted by somatotropes (acidophilic cells) in the anterior pituitary
    • Protein in nature, single chain polypeptide with 191 amino acids and a molecular weight of 21,500
    • Basal level in adults is less than 3 ng/mL; in children/adolescents, about 6 ng/mL
    • Transported in blood by GH-binding proteins (GHBPs)
    • Half-life of circulating GH is approximately 20 minutes
    • Degraded in the liver and kidneys

    Action of Growth Hormone

    • Promotes general body growth by increasing cell size (hypertrophy) and cell number (mitosis).
    • Influences differentiation of specific cell types (e.g., bone, muscle)

    Physiological Effects of GH

    Effect on Metabolism

    • Increases protein synthesis
    • Mobilizes lipids
    • Conserves carbohydrates
    Protein Metabolism
    • Increases amino acid transport through cell membranes
    • Increases RNA translation
    • Increases DNA transcription to RNA
    • Decreases protein catabolism
    • Promotes protein anabolism indirectly (by increasing insulin release).
    Fat Metabolism
    • Mobilizes fats from adipose tissue, providing fatty acids for energy production
    • Reduces protein use for energy
    Carbohydrate Metabolism
    • Conserves glucose by decreasing its peripheral utilization.
    • Increases glycogen deposition in cells
    • Decreases glucose uptake into cells (diabetogenic effect)
    • High GH can stimulate insulin secretion.

    Effect on Bone Growth

    • During embryonic development, responsible for bone differentiation and growth
    • Increases both bone length and thickness
    • Stimulates chondrocytes and osteogenic cells, promoting synthesis and deposition of proteins.
    • Promotes chondrocyte multiplication and conversion of chondrocytes into osteogenic cells. This results in new bone formation.

    Somatomedins/Insulin-like Growth Factor (IGF)

    • Polypeptides secreted by the liver, acting as intermediaries for GH's effects.
    • Two Types:
      • IGF-I (somatomedin C): Acts on bones and protein metabolism, with slow release from plasma proteins and duration of action up to 20 hours.
      • IGF-II: Plays a role in fetal growth.

    Effect on Electrolytes

    • GH decreases the elimination of electrolytes from the body, shifting these electrolytes to tissues for growth.

    GH Secretion Regulation

    • Stimulated by:
      • Hypoglycemia
      • Fasting/Starvation
      • Exercise
      • Stress and Trauma
      • Initial stages of sleep
    • Inhibited by:
      • Hyperglycemia
      • Increased free fatty acids in blood
      • Later stages of sleep

    Role of Hypothalamus in GH Secretion

    • Regulates GH secretion through three hormones:
      • GHRH (Growth Hormone-Releasing Hormone): Stimulates somatotropes in the anterior pituitary
      • GHRP (Growth Hormone-Releasing Polypeptide): Increases GHRH release from hypothalamus and GH release.
      • GHIH (Growth Hormone-Inhibitory Hormone) / Somatostatin: Inhibits GH secretion.

    Gigantism

    • Hypersecretion of GH in childhood before epiphyseal closure results in excessive growth
    • Often due to a tumor in the anterior pituitary.

    Acromegaly

    • Hypersecretion of GH in adulthood after epiphyseal closure. This results in enlargement and thickening of bones and soft tissues, especially in the face, hands, and feet
    • Often due to a tumor in the anterior pituitary

    Dwarfism

    • Hypoactivity or hyposecretion of GH in childhood leads to stunted growth.
    • Possible causes: Tumors of chromophobes (non-functioning tumors of the pituitary gland), Panhypopituitarism (deficiency of all pituitary hormones).

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    Growth Hormone (GH) PDF

    Description

    This quiz explores the functions and effects of Growth Hormone (GH), detailing its secreted nature, physiological actions, and impact on metabolism. Gain insights into how GH influences growth and development at both cellular and systemic levels.

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