Pituitary-Adrenal Axis and Hormone Regulation
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Questions and Answers

What is one of the primary symptoms of hypocortisolism, such as in Addison's disease?

  • Hyperglycemia
  • Hypertension
  • Hypoglycemia (correct)
  • Increased appetite

    • Which condition is characterized by high cortisol levels due to adrenal gland hyperactivity?

  • Primary adrenal insufficiency
  • Congenital adrenal hyperplasia
  • Addison's Disease
  • Cushing's Disease (correct)

    • What is a key difference between Cushing's Syndrome and Cushing's Disease?

  • Cushing's Disease is more likely to cause Addison's symptoms than Cushing's Syndrome.
  • Cushing's Syndrome is always due to adrenal tumors, while Cushing's Disease is not.
  • Cushing's Disease is hereditary, whereas Cushing's Syndrome is acquired.
  • Cushing's Disease involves overproduction of ACTH, while Cushing's Syndrome can arise from cortisol-producing tumors. (correct)

    • Which of the following is NOT a potential consequence of prolonged high glucocorticoid levels?

    <p>Weight loss</p> Signup and view all the answers

    What role does 11β-HSD2 play in the effects of cortisol in the body?

    <p>It inactivates cortisol to prevent its action.</p> Signup and view all the answers

    What is a primary characteristic of Addison's disease?

    <p>Insufficient production of steroid hormones</p> Signup and view all the answers

    Which of the following is a symptom of hypoadrenalism in Addison's disease?

    <p>Hyperpigmentation of the skin</p> Signup and view all the answers

    Which condition is characterized by muscle wasting and fat accumulation due to excess glucocorticoids?

    <p>Cushing's syndrome</p> Signup and view all the answers

    What defines the difference between Cushing's syndrome and Cushing's disease?

    <p>Cushing's syndrome is caused by adrenal gland tumors, while Cushing's disease is due to pituitary adenomas.</p> Signup and view all the answers

    Which of these symptoms is commonly associated with glucocorticoid deficiency in Addison's disease?

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

    Peripheral edema is associated with which condition related to glucocorticoid levels?

    <p>Cushing's syndrome</p> Signup and view all the answers

    What effect does elevated plasma potassium have in Addison's disease?

    <p>Muscle fatigue and pain</p> Signup and view all the answers

    Which of the following is NOT a symptom of Cushing's syndrome?

    <p>Salt craving</p> Signup and view all the answers

    What condition is characterized by excess cortisol in the body?

    <p>Cushing's Syndrome</p> Signup and view all the answers

    Which of the following symptoms is primarily associated with Addison's Disease?

    <p>Hyperpigmentation of the skin</p> Signup and view all the answers

    Which hormone is primarily responsible for the regulation of cortisol release?

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

    What is a common physiological effect of excess cortisol in Cushing's Syndrome?

    <p>Increased plasma glucose levels</p> Signup and view all the answers

    Cushing's Disease specifically refers to what type of condition?

    <p>Pituitary adenomas secreting ACTH</p> Signup and view all the answers

    Which of the following conditions could lead to adrenal hyperplasia?

    <p>Chronic high levels of ACTH</p> Signup and view all the answers

    What is a potential consequence of hypocortisolism?

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

    What is the primary role of aldosterone in the body?

    <p>Regulating salt and water balance</p> Signup and view all the answers

    How do steroid hormones, like cortisol, primarily affect their target cells?

    <p>By acting on intracellular receptors</p> Signup and view all the answers

    Which of the following statements about cortisol is true?

    <p>It is freely permeable to membranes</p> Signup and view all the answers

    What is primarily responsible for hyperglycemia in hypercortisolism?

    <p>Increased levels of glucocorticoids</p> Signup and view all the answers

    Which of the following characterizes Cushing's disease?

    <p>Increased ACTH due to a pituitary adenoma</p> Signup and view all the answers

    What leads to adrenal hyperplasia in the case of hypocortisolism?

    <p>Impaired feedback resulting in excess CRH and ACTH</p> Signup and view all the answers

    Which symptom is associated with 21-hydroxylase deficiency in females?

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

    What is the most likely consequence of prolonged hypertension due to hypercortisolism?

    <p>Development of cardiac hypertrophy</p> Signup and view all the answers

    In Cushing's syndrome, what type of tumors can cause endogenous overproduction of cortisol?

    <p>Both B and C</p> Signup and view all the answers

    What is a possible mechanism for excess ACTH to influence androgen production during stress?

    <p>Shunting into the androgen production pathway</p> Signup and view all the answers

    What leads to a moon face appearance in patients with hypercortisolism?

    <p>Fluid retention from salt and water retention</p> Signup and view all the answers

    Which condition is characterized by dependency on exogenous glucocorticoids?

    <p>Addison's disease</p> Signup and view all the answers

    What is a common effect of excess cortisol levels on potassium in the body?

    <p>Decreased potassium levels</p> Signup and view all the answers

    What is a common symptom associated with hypocortisolism?

    <p>Fatigue and weakness</p> Signup and view all the answers

    Which of the following conditions is characterized by excessive cortisol production?

    <p>Cushing's Syndrome</p> Signup and view all the answers

    Which of the following best differentiates Cushing's Disease from Cushing's Syndrome?

    <p>Cushing's Disease involves a pituitary tumor</p> Signup and view all the answers

    What is a potential effect of hypercortisolism on the immune system?

    <p>Suppression of immune function</p> Signup and view all the answers

    Which enzyme is responsible for converting cortisol to its active form in specific tissues?

    <p>11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1)</p> Signup and view all the answers

    Which symptom is NOT typically associated with Addison's Disease?

    <p>Rapid weight gain</p> Signup and view all the answers

    What effect does cortisol have on blood glucose levels during stress?

    <p>Elevates blood glucose levels</p> Signup and view all the answers

    How does cortisol affect bone formation?

    <p>Inhibits bone formation</p> Signup and view all the answers

    What is a common side effect of long-term glucocorticoid use?

    <p>Weight gain and hypertension</p> Signup and view all the answers

    What is the role of mineralocorticoid receptor (MR) in the action of cortisol?

    <p>It mediates the genomic effects of cortisol</p> Signup and view all the answers

    Study Notes

    Pituitary-Adrenal Axis

    • The pituitary-adrenal axis is a system of hormone regulation.
    • Cortisol is a glucocorticoid hormone synthesized in the adrenal cortex.
    • Steroid hormones are lipid-soluble, freely permeate cell membranes, and are carried in the blood complexed to globulins.

    Learning Objectives

    • Identify the class of hormone to which cortisol belongs and its synthesis location.
    • Describe steroid hormone signaling events.
    • Understand ACTH release regulation and its effects on cortisol release.
    • Explain cortisol's mechanisms of action and its target sites.
    • Describe consequences of cortisol excess and deficiency, including phenotypes in Cushing's syndrome and Addison's disease.

    Adrenal Gland

    • The adrenal gland comprises a cortex and medulla.
    • The adrenal cortex produces steroid hormones:
      • Cortisol (glucocorticoid), regulating glucose levels.
      • Aldosterone (mineralocorticoid), promoting salt and water retention.
      • Androgens, which can be converted to testosterone.
    • The adrenal medulla produces catecholamines:
      • Epinephrine (adrenaline)
      • Norepinephrine, a precursor of epinephrine.

    Steroid Hormone Synthesis

    • Steroid hormones are derived from cholesterol.
    • Cholesterol synthesis occurs in the cell's mitochondria and Smooth ER.
    • The rate-limiting step is the transport of free cholesterol into mitochondria, carried out by StAR.
    • The converted cholesterol into pregnenolone by cytochrome P450 side-chain cleavage enzymes.

    Cortisol Transport and Metabolism

    • Cortisol is transported in the blood predominantly bound to corticosteroid-binding globulin (CBG), and albumin.
    • The free form of cortisol exerts effects in target cells, feedbacking on the pituitary and hypothalamus.
    • The liver inactivates and conjugates 95% of active and inactive steroids for excretion.
    • Cortisol's circulating half-life is approximately 70 minutes.

    Mechanism of Cortisol Action

    • Cortisol primarily acts through the glucocorticoid receptor (GR), localized in the cytoplasm or nucleus.
    • The cortisol-GR complex translocates to the nucleus, binds to glucocorticoid response elements, and regulates gene transcription.

    Metabolic Effects of Cortisol

    • Cortisol stimulates protein and triglyceride catabolism.
    • It stimulates gluconeogenesis in the liver, inhibiting glucose uptake and thus causing a diabetogenic effect but not on brain.
    • Cortisol inhibits bone formation and non-essential functions like reproduction and growth.
    • Cortisol is essential for life.

    Effects of Altered Glucocorticoid Levels

    • Cushing's Syndrome: Excess cortisol; causes: Salt and water retention, muscle wasting, fat accumulation, osteoporosis, thin skin, poor wound healing.
    • Addison's Disease: Insufficient cortisol; causes: Skin hyperpigmentation, hypoglycemia, hypotension, muscle weakness, and electrolyte imbalances.

    Regulation of Glucocorticoid Secretion

    • The hypothalamic-pituitary-adrenal (HPA) axis regulates cortisol secretion.
    • The HPA axis is a centrally driven response to stress, regulating cortisol levels cyclically by a diurnal rhythm.

    Adrenal Hyperplasia

    • 21-hydroxylase deficiency: A genetic defect that alters steroid production, characterized by varying degrees of virilism in females.

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    Description

    Explore the intricacies of the pituitary-adrenal axis and its role in hormone regulation. This quiz covers the synthesis and action of cortisol, the effect of ACTH, and the consequences of hormonal imbalances, including Cushing's syndrome and Addison's disease.

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