BMS200 - Week 3
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Questions and Answers

What is the primary function of vasopressin (ADH) released from the posterior pituitary?

  • Stimulate ACTH release
  • Promote water reabsorption (correct)
  • Inhibit GH release
  • Stimulate uterine contractions
  • Which neurons are primarily responsible for releasing hormones into the systemic circulation through the posterior pituitary?

  • Magnocellular neurons (correct)
  • Corticotroph neurons
  • Thyroid neurons
  • Parvocellular neurons
  • What role do releasing hormones from the hypothalamus play in relation to the anterior pituitary?

  • Modulate hormone secretion from anterior pituitary cells (correct)
  • Directly produce anterior pituitary hormones
  • Transport blood to the anterior pituitary
  • Inhibit the action of neurohormones
  • The primary function of Gonadotropin Releasing Hormone (GnRH) is to:

    <p>Stimulate Gonadotropin release</p> Signup and view all the answers

    What structure connects the hypothalamus to the anterior pituitary and serves as the site of neurohormone release?

    <p>Median eminence</p> Signup and view all the answers

    What is the primary function of the hypothalamus in relation to the pituitary gland?

    <p>To integrate signals and send outputs to the pituitary gland</p> Signup and view all the answers

    What is a key feature of the hypothalamic-pituitary-target gland axis?

    <p>It includes both short and long feedback loops for regulation</p> Signup and view all the answers

    How does the hypothalamus primarily receive signals regarding the body's status?

    <p>Using various receptors that process signals from the bloodstream</p> Signup and view all the answers

    Which conditions are associated with abnormal growth hormone production?

    <p>Acromegaly and gigantism</p> Signup and view all the answers

    What role does prolactin play in the hormonal regulation within the body?

    <p>It coordinates cross-talk with other hypothalamic hormones</p> Signup and view all the answers

    What directly regulates the release of cortisol from the adrenal gland?

    <p>ACTH from the anterior pituitary</p> Signup and view all the answers

    How are steroid hormones different from catecholamines in terms of secretion?

    <p>Steroid hormones can cross cell membranes without vesicles.</p> Signup and view all the answers

    What determines the type of steroid hormone produced by a cell in the adrenal cortex?

    <p>The enzymes expressed by the cell</p> Signup and view all the answers

    Which factor does NOT influence the rate of steroid hormone secretion?

    <p>Storage of hormones in vesicles</p> Signup and view all the answers

    Which type of hormone secretion is primarily influenced by enzymatic activation and exocytosis?

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

    What is the primary function of aldosterone produced by the zona glomerulosa of the adrenal cortex?

    <p>Controlling sodium and water balance</p> Signup and view all the answers

    Which statement is true regarding the adrenal medulla?

    <p>It functions as an overgrown sympathetic ganglion</p> Signup and view all the answers

    Which zone of the adrenal cortex is responsible for producing cortisol?

    <p>Zona fasciculata</p> Signup and view all the answers

    The adrenal cortex and adrenal medulla differ primarily in their methods of hormone regulation; which statement best describes this difference?

    <p>The cortex operates through hormonal regulation and longer-term stress responses, while the medulla involves rapid sympathetic responses.</p> Signup and view all the answers

    What is the developmental origin of the adrenal cortex?

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

    What terminology describes dysfunction at the level of the pituitary gland?

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

    Which of the following is a common clinical feature associated with Cushing's syndrome?

    <p>Moon facies</p> Signup and view all the answers

    Which test is most directly associated with diagnosing adrenal insufficiency in patients?

    <p>Cortisol testing</p> Signup and view all the answers

    What is the primary pathophysiological mechanism underlying Conn's disease?

    <p>Excess production of aldosterone</p> Signup and view all the answers

    In congenital adrenal hyperplasia, which enzyme deficiency is most commonly implicated?

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

    What is a common source of excess cortisol in Cushing's syndrome?

    <p>Iatrogenic factors</p> Signup and view all the answers

    Which statement is true regarding the incidence of endogenous hypercortisolism?

    <p>It predominantly affects women in their 20s and 30s.</p> Signup and view all the answers

    What characterizes Cushing Disease?

    <p>An ACTH-producing microadenoma in the pituitary gland</p> Signup and view all the answers

    Which condition accounts for approximately 10% of cases of Cushing's syndrome?

    <p>Paraneoplastic syndrome</p> Signup and view all the answers

    How is primary Cushing syndrome typically caused?

    <p>Adenoma in the adrenal glands themselves</p> Signup and view all the answers

    Study Notes

    Introduction to Endocrinology

    • Focus on the hypothalamus, pituitary gland, thyroid gland, and adrenal glands.
    • Understand the hypothalamic-pituitary-target gland axis and feedback loops.

    Hypothalamus Anatomy

    • Composed of various nuclei containing diverse neuron types.
    • Integrates signals regarding thirst, blood pressure, appetite, and temperature.
    • Situated near the third ventricle, allowing selective signal passage from blood.

    Hypothalamic Neurohormones

    • Magnocellular neurons produce oxytocin and vasopressin, released into systemic circulation.
    • Parvocellular neurons produce CRH, TRH, GHRH, among others, influencing the anterior pituitary via the median eminence.

    Hypothalamic-Pituitary Communication

    • Releasing or inhibiting hormones from the hypothalamus enter the first capillary set and modulate hormone secretion in the anterior pituitary.
    • The anterior pituitary regulates thyroid, adrenal glands, gonads, and liver hormone levels.

    Hypothalamic Regulation Mechanism

    • Integrates input from the central nervous system and various body signals.
    • Neurons detect glucose levels and osmolarity, facilitating response adjustments.
    • Negative feedback (e.g., CRH-ACTH suppression) and positive feedback (e.g., oxytocin during childbirth) loops regulate hormone release.

    Functions of Growth Hormone (GH)

    • Increases bone and cartilage growth, particularly during puberty.
    • Promotes lipolysis in adipose tissue and enhances protein synthesis in skeletal muscle.
    • Stimulates liver to produce IGF-1 and influences immune system activity.

    Somatomedins and IGF-1

    • IGF-1 is regulated by GH and factors like PTH; crucial for bone formation and metabolic functions.
    • Levels of IGF-1 rise during childhood/puberty and decline in the third decade of life.

    Complications of Excess GH

    • Acromegaly often arises from somatotrope adenomas, leading to bony overgrowth and soft tissue changes.
    • Symptoms include enlarged hands/feet, facial feature alterations, and increased heel pad thickness.

    Feedback Loops Definitions

    • Long loop: feedback from target endocrine gland to hypothalamus/pituitary.
    • Short loop: feedback from the pituitary to its own releasing hormone.

    Key Questions

    • Identify the primary physiological effects of GH and associated receptor families.
    • Understand the main role of prolactin in mammary gland function.

    Important Terms

    • Magnocellular Neurons: Produce oxytocin and vasopressin, impacting major bodily functions.
    • Parvocellular Neurons: Produce a variety of neurohormones affecting anterior pituitary functions.
    • Acromegaly: Condition characterized by excessive growth hormone leading to prominent physical changes.

    Adrenal Glands Overview

    • Adrenal glands respond to stress via chemical signals, increasing heart rate, blood pressure, and energy availability.
    • Comprised of two main regions: adrenal cortex (hormonal functions) and adrenal medulla (nervous system functions).

    Embryological Development

    • Adrenal cortex develops from mesoderm, contributing to structures like muscles and bones.
    • Adrenal medulla arises from neural crest cells, functioning as an "overgrown sympathetic ganglion."

    Adrenal Cortex Zones

    • Zona Glomerulosa: Produces aldosterone for blood pressure regulation.
    • Zona Fasciculata: Largest zone, secretes cortisol for metabolism and stress response regulation.
    • Zona Reticularis: Produces androgens, precursors for testosterone and estrogen.

    Hypothalamic-Pituitary Axis (HPA)

    • HPA manages hormonal communication between hypothalamus and anterior pituitary.
    • Hormones from the hypothalamus (CRH, TRH, GnRH) influence adrenal gland activity.
    • Cortisol release regulated by ACTH; Aldosterone regulated by angiotensin II and serum K+ levels; Epinephrine governed by sympathetic nervous system.

    Hormone Production and Secretion

    • Steroid hormones like cortisol and aldosterone synthesized from cholesterol on demand; not stored in cells.
    • Secretion of steroid hormones doesn’t require exocytosis due to their lipid-soluble nature.
    • Enzyme activity dictates types of steroid hormones produced in specific adrenal cortex zones.

    Effects of Glucocorticoids

    • Aid in fetal lung and liver development; excess can impair bone formation and healing.
    • Increase effectiveness of catecholamines, cardiac output, and blood pressure; may cause euphoria followed by mood disturbances.
    • Short-term elevation boosts immune cell activity, while long-term elevation can impair healing and cell migration.

    Regulation of Mineralocorticoids

    • Mineralocorticoids like aldosterone mainly regulated by the renin-angiotensin-aldosterone system (RAAS) and serum K+ levels.
    • Renin release from the kidney triggers the conversion of angiotensin to angiotensin I, leading to vasoconstriction and aldosterone secretion.

    Catecholamines Function and Catabolism

    • Epinephrine and norepinephrine enhance heart contractility, elevate heart rate, and stimulate energy metabolism.
    • Broken down in the liver and kidneys into metabolites like vanillylmandelic acid (VMA) via enzymes MAO and COMT.
    • Catabolism ensures consistent hormone levels, preventing overstimulation post stress response.

    Adrenal Pathologies Overview

    • Disorders of adrenal glands can involve either hyperfunction (excess hormone production) or hypofunction (insufficient hormone production).
    • Hyperfunction results in elevated levels of cortisol or aldosterone; hypofunction typically results in significant insufficiencies of the adrenal cortex.

    Cushing Syndrome and Disease

    • Cushing syndrome is characterized by elevated glucocorticoid levels due to various causes, including iatrogenic effects and endogenous factors such as pituitary diseases and adrenal tumors.
    • Cushing disease specifically refers to endogenous hypercortisolism linked to ACTH-producing pituitary microadenomas, mostly affecting women in their twenties and thirties.
    • Ectopic ACTH secretion by tumors (e.g., small cell lung cancer) accounts for about 10% of Cushing syndrome cases.
    • Primary Cushing syndrome can arise from adrenal adenomas, which are typically well-differentiated and more common in women.

    Adrenocortical Insufficiency

    • Adrenal insufficiency can be acute or chronic, categorized as primary (Addison's disease) or secondary due to reduced ACTH.
    • Acute insufficiency may occur after rapid withdrawal of glucocorticoids, resulting in an adrenal crisis.

    Addison Disease

    • Rare, chronic primary adrenal insufficiency caused by destruction of the adrenal cortex, often autoimmune in nature.
    • Symptoms appear after significant loss (about 90%) of adrenal function, including weakness, gastrointestinal disturbances, hyperpigmentation, and electrolyte imbalances.
    • Secondary adrenal insufficiency lacks hyperpigmentation and typically maintains normal aldosterone levels.

    Primary Hyperaldosteronism

    • Caused by excessive aldosterone secretion, leading to hypertension and hypokalemia.
    • Often results from an adrenocortical neoplasm (Conn's syndrome) or bilateral adrenal hyperplasia.

    Congenital Adrenal Hyperplasia (CAH)

    • Autosomal recessive disorder primarily affecting cortisol synthesis, most commonly due to 21-hydroxylase deficiency.
    • Classic forms include salt-wasting and simple virilizing, while non-classic forms present later in life, often resembling polycystic ovary syndrome in women.

    Pheochromocytoma

    • A rare tumor of adrenal medulla chromaffin cells, typically secreting excess catecholamines, leading to persistent or paroxysmal hypertension.
    • Surgical excision is a common treatment option, and elevated catecholamine levels may be detectable in urine.

    Diagnostic Tests

    • Various tests assist in diagnosing adrenal pathologies, including:
      • Insulin tolerance test
      • CRH stimulation test
      • ACTH stimulation tests (to differentiate between primary and secondary adrenal insufficiency)
      • Cortisol and ACTH level measurements
      • Dexamethasone suppression test

    Key Terminology

    • Tertiary: dysfunction at the hypothalamus
    • Secondary: dysfunction at the pituitary gland
    • Primary: dysfunction within the adrenal glands

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    Related Documents

    Adrenal Physiology PDF
    Adrenal Pathology Week 3 PDF

    Description

    Explore the complex interactions within the endocrine system, focusing on the hypothalamus, pituitary gland, thyroid gland, and adrenal glands. This quiz will enhance your understanding of the hypothalamic-pituitary-target gland axis and the feedback mechanisms that regulate hormonal balance.

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