Adrenal Gland Anatomy and Function
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Questions and Answers

What percentage of the adrenal gland is made up of the adrenal cortex?

  • 20%
  • 50%
  • 80% (correct)
  • 100%

    • Which layer of the adrenal cortex is the outermost?

  • Zona fasciculata
  • Zona glomerulosa (correct)
  • Adrenal medulla
  • Zona reticularis

    • Which hormone is primarily responsible for mineralocorticoid activity?

  • Epinephrine
  • Testosterone
  • Cortisol
  • Aldosterone (correct)

    • What is a primary function of aldosterone?

    <p>Reabsorption of sodium</p> Signup and view all the answers

    During hypersecretion of aldosterone, what is the expected sodium loss through urine?

    <p>Few milligrams per day</p> Signup and view all the answers

    Which of the following actions does aldosterone NOT perform?

    <p>Decrease hydrogen secretion</p> Signup and view all the answers

    What byproduct is formed when corticosteroids are degraded in the liver?

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

    What condition can result from hyposecretion of aldosterone?

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

    What process is responsible for the uptake of tyrosine into chromaffin cells of the adrenal medulla?

    <p>Active transport</p> Signup and view all the answers

    Which enzyme is responsible for converting tyrosine into dihydroxyphenylalanine (DOPA)?

    <p>Tyrosine hydroxylase</p> Signup and view all the answers

    What percentage of noradrenaline is taken up by sympathetic adrenergic neurons?

    <p>85%</p> Signup and view all the answers

    What is the end product of the oxidation of metanephrines by monoamine oxidase (MAO)?

    <p>Vanillylmandelic acid (VMA)</p> Signup and view all the answers

    Which form does the majority of catecholamines get removed from the body through urine?

    <p>Conjugated meta-adrenaline</p> Signup and view all the answers

    How does adrenaline primarily exert its effects on target organs?

    <p>By binding to adrenergic receptors</p> Signup and view all the answers

    What is considered the most important enzyme for the methylation of noradrenaline into adrenaline?

    <p>Phenylethanolamine N-methyltransferase (PNMT)</p> Signup and view all the answers

    What happens to adrenaline and noradrenaline in terms of metabolic action?

    <p>They stimulate the nervous system and affect metabolic functions.</p> Signup and view all the answers

    What primary condition leads to the pigmentation of skin and mucous membranes due to excess ACTH secretion?

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

    What is a significant test for diagnosing Addison Disease?

    <p>Measurement of cortisol and aldosterone levels</p> Signup and view all the answers

    Which symptom is NOT typically associated with an Addisonian crisis?

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

    What causative factor can induce an Addisonian crisis?

    <p>Withdrawal of glucocorticoid treatment</p> Signup and view all the answers

    What is typically true about congenital adrenal hyperplasia regarding cortisol secretion?

    <p>Cortisol secretion is decreased</p> Signup and view all the answers

    What causes the adrenal cortex to increase in size in congenital adrenal hyperplasia?

    <p>Increased number of steroid-secreting cells</p> Signup and view all the answers

    What enzyme deficiency primarily affects cortisol synthesis in congenital adrenal hyperplasia?

    <p>21-hydroxylase</p> Signup and view all the answers

    Which of the following symptoms would likely NOT be associated with cortisol deficiency?

    <p>Acne and increased sweating</p> Signup and view all the answers

    What is the primary catecholamine found in the granules of chromaffin cells?

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

    Which of the following conditions can stimulate the secretion of stored catecholamines from chromaffin cells?

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

    Pheochromocytomas primarily arise from which type of cells?

    <p>Chromaffin cells</p> Signup and view all the answers

    What is a key symptom associated with pheochromocytomas?

    <p>Sustained hypertension</p> Signup and view all the answers

    Where are chromaffin cells also located besides the adrenal medulla?

    <p>Preaortic sympathetic plexuses</p> Signup and view all the answers

    What type of neurons provide the innervation to the adrenal medulla?

    <p>Cholinergic preganglionic sympathetic neurons</p> Signup and view all the answers

    Which of the following tumors is considered similar to pheochromocytomas?

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

    Chromaffin cells can be identified due to their affinity for which element?

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

    What primary effect does adrenaline have on heart rate?

    <p>Increases heart rate</p> Signup and view all the answers

    Which receptor is primarily responsible for the vasoconstrictor effect of noradrenaline on blood vessels?

    <p>Alpha receptors</p> Signup and view all the answers

    How does adrenaline affect diastolic blood pressure?

    <p>Decreases diastolic blood pressure</p> Signup and view all the answers

    Which of the following statements about catecholamines is true?

    <p>They have a prolonged effect compared to sympathetic stimulation.</p> Signup and view all the answers

    Which type of adrenergic receptor is involved in increasing the force of contraction of the heart?

    <p>Beta-1 receptors</p> Signup and view all the answers

    What is the effect of noradrenaline on systolic blood pressure?

    <p>It increases systolic blood pressure to a slight extent.</p> Signup and view all the answers

    How do adrenaline and noradrenaline differ in their effects on blood vessels?

    <p>Adrenaline dilates blood vessels in skeletal muscle, liver, and heart.</p> Signup and view all the answers

    Which statement accurately reflects the role of glucocorticoids in relation to catecholamines?

    <p>They enhance the effects of catecholamines on blood pressure.</p> Signup and view all the answers

    Study Notes

    Adrenal Gland Structure

    • Composed of two main parts:
      • Adrenal cortex (80% of the gland)
      • Adrenal medulla (20% of the gland)

    Histology of Adrenal Cortex

    • Adrenal cortex consists of three distinct layers:
      • Outer zona glomerulosa
      • Middle zona fasciculata
      • Inner zona reticularis

    Hormones of Adrenal Cortex

    • Adrenocortical hormones are steroid-based (corticosteroids)
    • Classified into three groups:
      • Mineralocorticoids
      • Glucocorticoids
      • Sex hormones

    Fate of Corticosteroids

    • Primarily degraded in the liver
    • Conjugated to form glucuronides and sulfates
    • Approximately 25% excreted in bile and feces, 75% in urine

    Mineralocorticoids

    • Regulate minerals (electrolytes) such as sodium and potassium
    • Key mineralocorticoids:
      • Aldosterone
      • 11-deoxycorticosterone
    • Secreted by zona glomerulosa of the adrenal cortex

    Functions of Aldosterone

    • Increases sodium reabsorption, potassium excretion, and hydrogen secretion in renal tubules
    • In cases of hypersecretion, minimal loss of sodium occurs; in hyposecretion, sodium loss increases significantly (hypernatriuria)

    Cortisol Deficiency Effects

    • Excess ACTH secretion leads to pigmentation of skin and mucous membranes
    • Symptoms include:
      • Muscular weakness
      • Dehydration and sodium loss
      • Hypotension
      • Decreased cardiac output
      • Hypoglycemia
      • Nausea, vomiting, diarrhea
      • Increased susceptibility to infections
      • Difficulty handling stress (Addisonian crisis)

    Tests for Addison Disease

    • Blood tests for cortisol and aldosterone levels
    • Urine steroid excretion measurement

    Addisonian Crisis

    • Characterized by sudden collapse with an increased need for glucocorticoids
    • Can be triggered by:
      • Mild stress
      • Fasting-related hypoglycemia
      • Trauma
      • Surgery
      • Withdrawal from glucocorticoid therapy

    Congenital Adrenal Hyperplasia

    • Congenital disorder leading to increased adrenal cortex size due to increased steroid-secreting cells
    • Caused by enzyme deficiencies (e.g., 21-hydroxylase) leading to decreased cortisol but increased ACTH, causing hyperplasia

    Catecholamine Synthesis

    • Tyrosine uptake and conversion into catecholamines occur in chromaffin cells of the adrenal medulla:
      • Tyrosine to DOPA (by tyrosine hydroxylase)
      • DOPA to dopamine (by DOPA decarboxylase)
      • Dopamine to noradrenaline (by dopamine beta-hydroxylase)
      • Noradrenaline to adrenaline (by phenylethanolamine N-methyltransferase)

    Metabolism of Catecholamines

    • 85% of noradrenaline taken up by sympathetic adrenergic neurons
    • Remaining 15% metabolized into:
      • Meta-adrenaline (via COMT)
      • Vanillylmandelic acid (VMA, via MAO)
    • Catecholamines are excreted in urine as:
      • Free adrenaline and noradrenaline (15%)
      • Meta-adrenaline and meta-noradrenaline (50%)
      • VMA (35%)

    Actions of Adrenaline and Noradrenaline

    • Stimulate nervous system with significant metabolic and cardiovascular effects
    • Bind to adrenergic receptors in target organs, with two main types:
      • Alpha-adrenergic receptors (α1, α2)
      • Beta-adrenergic receptors (β1, β2)

    Effects on Heart and Blood Vessels

    • Adrenaline (via beta receptors) increases:
      • Heart rate
      • Force of contraction
      • Excitability and conductivity of the heart
    • Noradrenaline acts as a general vasoconstrictor via alpha receptors, increasing total peripheral resistance
    • Adrenaline causes vasodilation in skeletal muscle, liver, and heart via beta-2 receptors, decreasing total peripheral resistance

    Blood Pressure Regulation

    • Adrenaline raises systolic blood pressure while lowering diastolic pressure
    • Noradrenaline increases both systolic and diastolic pressures due to vasoconstriction effects

    Chromaffin Cells

    • Found in adrenal medulla and sympathetic nervous system sites
    • Release catecholamines during stress or excitement

    Pheochromocytoma

    • Rare tumors of chromaffin cells in adrenal medulla or extra-adrenal sites
    • More common in women, occurring at any age but rare over 60
    • Symptoms include sustained or episodic hypertension, pallor, anxiety, and cardiac arrhythmias

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    Adrenal Gland PDF

    Description

    Explore the structure and function of the adrenal gland in this quiz. Focus on the distinct parts of the gland, including the adrenal cortex and medulla, as well as the histology and hormones produced by the adrenal cortex. Test your knowledge on these essential components of human physiology.

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