Podcast
Questions and Answers
Which cells in the anterior pituitary gland are responsible for the production of growth hormone (GH)?
Which cells in the anterior pituitary gland are responsible for the production of growth hormone (GH)?
What is the primary mediator of growth hormone's physiological actions?
What is the primary mediator of growth hormone's physiological actions?
During which developmental stage does IGF-1 experience its greatest surge?
During which developmental stage does IGF-1 experience its greatest surge?
Which hormone's levels are typically measured to evaluate for a deficiency or excess of growth hormone?
Which hormone's levels are typically measured to evaluate for a deficiency or excess of growth hormone?
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What role does growth hormone play in the body?
What role does growth hormone play in the body?
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Which of the following hormones is structurally similar to growth hormone?
Which of the following hormones is structurally similar to growth hormone?
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What is the nature of growth hormone release from the anterior pituitary gland?
What is the nature of growth hormone release from the anterior pituitary gland?
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Which process is primarily influenced by growth hormone in skeletal muscle?
Which process is primarily influenced by growth hormone in skeletal muscle?
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What condition results from excess GH secretion before puberty?
What condition results from excess GH secretion before puberty?
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Which hormone is primarily produced by lactotrophs in the anterior pituitary gland?
Which hormone is primarily produced by lactotrophs in the anterior pituitary gland?
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Which hormone would most likely increase the serum level of growth hormone?
Which hormone would most likely increase the serum level of growth hormone?
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What is the major physiological action of prolactin?
What is the major physiological action of prolactin?
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In acromegaly, which of the following continues to grow after puberty?
In acromegaly, which of the following continues to grow after puberty?
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Where is somatomedin C primarily formed?
Where is somatomedin C primarily formed?
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Which hormone is known for regulating glucose utilization and may lead to hyperglycemia when in excess?
Which hormone is known for regulating glucose utilization and may lead to hyperglycemia when in excess?
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What effect does somatostatin have on growth hormone release?
What effect does somatostatin have on growth hormone release?
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What is the primary role of ghrelin in relation to growth hormone?
What is the primary role of ghrelin in relation to growth hormone?
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How do GH and IGF-1 primarily contribute to linear bone growth in children?
How do GH and IGF-1 primarily contribute to linear bone growth in children?
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What physiological effect does growth hormone (GH) have on serum glucose levels?
What physiological effect does growth hormone (GH) have on serum glucose levels?
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What condition can results from a deficiency of growth hormone in children?
What condition can results from a deficiency of growth hormone in children?
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What strategy is sometimes employed to address short stature in children?
What strategy is sometimes employed to address short stature in children?
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What metabolic processes are stimulated by GH and IGF-1 to support growth?
What metabolic processes are stimulated by GH and IGF-1 to support growth?
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Which of the following hormonal actions is not primarily associated with prolactin?
Which of the following hormonal actions is not primarily associated with prolactin?
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Which of the following accurately describes the regulation of GH release?
Which of the following accurately describes the regulation of GH release?
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Study Notes
Anterior Pituitary Hormones
- Anterior pituitary hormones are crucial for various bodily functions
- Thyrotropin stimulates the thyroid gland
- Growth hormone (GH) increases blood glucose and promotes insulin secretion
- Corticotropin stimulates the adrenal cortex
- Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) affect the ovaries and testes
- Prolactin stimulates the mammary glands
Growth Hormone
- Growth hormone (GH), also known as somatotropin, is a peptide hormone
- Essential for bone growth
- Produced by somatotrophs in the anterior pituitary gland
- Structurally similar to prolactin
- Acts with insulin-like growth factor 1 (IGF-1) to stimulate bone and muscle growth
- Stimulates amino acid uptake, protein synthesis, DNA/RNA synthesis, and chondroitin sulfate/collagen production to increase cell size and number
Growth Hormone Regulation
- GHRH (growth hormone releasing hormone) stimulates GH release
- Somatostatin inhibits GH release
- Hypoglycemia, sleep, and stress stimulate GH release
- IGF-1 levels regulate GH release
- Aging and obesity inhibit GH release
Clinical Correlation Growth Hormone
- Clinically, IGF-1 is measured when evaluating GH deficiency or excess
- IGF-1 levels are more stable than GH fluctuations
- GH is released in pulses
Growth Hormone Action on Bones
- GH and IGF-1 stimulate linear bone growth at the epiphyseal plates
- Epiphyseal plates fuse by ages 18 (females) and 20 (males), ceasing linear bone growth
Growth Hormone Action on Muscles
- GH and IGF-1 stimulate skeletal muscle growth
- This occurs through myocyte hypertrophy (muscle cell enlargement) and increased protein synthesis
Increasing Serum Glucose
- GH and IGF-1 increase serum glucose concentration
- This is due to hepatic gluconeogenesis, lipolysis and lipid oxidation, and antagonism of insulin action.
- GH is believed to optimize the body for athletics by increasing blood sugar for muscle and bone building and increasing lipolysis for fat reduction.
Prolactin
- Prolactin is a peptide hormone produced by lactotrophs in the anterior pituitary
- Structurally similar to growth hormone
- Produced in the anterior pituitary
- Can also be produced by extra-pituitary tissue
Prolactin Function
- Known as the "milk hormone" due to its role in stimulating and enlarging the mammary glands for milk production
- Plays regulatory roles in reproduction, nerve formation, and fetal development.
- It affects tissues by binding to prolactin receptors.
- Acts indirectly on the gonads, influencing estrogen and testosterone production
Prolactin Regulation
- Dopamine is a key negative regulator of prolactin secretion
- Prolactin inhibits GnRH and thus FSH and LH production
- Nipple stimulation, estrogen, and thyrotropin-releasing hormone stimulate prolactin production
- Progesterone inhibits prolactin at the peripheral receptor levels
Clinical Correlation Prolactin
- Dopamine-increasing drugs, and antipsychotics and mood stabilizers affect prolactin levels
- Elevated prolactin levels are linked to amenorrhea (absence of menstruation) and infertility in women.
Prolactin in Pregnancy
- Prolactin is present at high, steady levels during pregnancy and breastfeeding
- Continuous elevated levels and inhibition by dopamine create a "reservoir" for prolactin release when needed
Dwarfism
- Results from a generalized deficiency of anterior pituitary hormone secretion before puberty, causing stunted growth
- Individuals may appear much younger than their actual age
- Some types have deficiency in gonadotropin and may not reach puberty
- One subtype has normal or high GH but lacks somatomedin C production
Gigantism
- Resulting from excess GH secretion before puberty
- Characterized by extreme height growth (exceeding 8 feet)
- Often associated with hyperglycemia and diabetes
Acromegaly
- Excess GH secretion after puberty
- Leads to enlarged features like hands, feet, jaw, and nose (cranial and supra-orbital bone growth).
- Can cause kyphosis (humped back)
- Increased organ size (e.g., kidney, liver, heart, tongue).
Learning Objectives (Growth Hormone)
- Identify GH synthesis and production sites
- Describe GH cellular binding and physiological actions
- Explain GH release regulation by anterior pituitary
- Describe prolactin cellular binding and physiological actions -Describe prolactin release regulation
Learning Objectives (Prolactin)
- Describe prolactin synthesis and production sites
- Identify prolactin cellular binding and physiological actions
- Describe prolactin release regulation
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