endocrine 2
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Questions and Answers

The pituitary gland is located within which structure?

  • The sella turcica of the sphenoid bone (correct)
  • The ethmoid plate
  • The foramen magnum of the occipital bone
  • The frontal sinus

    • What initiates the release of oxytocin during parturition through neural pathways?

  • Reflexes originating in the cervix and uterus. (correct)
  • The fetus pushing against the uterine wall.
  • A decrease in the hormone prolactin.
  • Increased levels of estrogen in the plasma.

    • What demonstrates the concept of a conditioned response related to oxytocin?

  • The release of oxytocin following the delivery of a fetus.
  • The release of oxytocin stimulated by cues associated with suckling. (correct)
  • Oxytocin production initiated by stimulation of the nipple area.
  • An increased release of oxytocin due to uterine contractions.

    • Which of the following describes the origin of the neurohypophysis?

    <p>Neuroepithelium of the diencephalon (D)</p> Signup and view all the answers

    Which of the following best describes the role of oxytocin during parturition?

    <p>It promotes uterine smooth muscle contractions for fetal delivery. (D)</p> Signup and view all the answers

    The anterior pituitary is also known as the:

    <p>Adenohypophysis (B)</p> Signup and view all the answers

    What is the primary function of the posterior pituitary?

    <p>Storing and secreting hormones received from the hypothalamus (A)</p> Signup and view all the answers

    During positive feedback, what is the biological response that results in increased hormone release, specifically for oxytocin?

    <p>Cervical dilation due to uterine contractions. (C)</p> Signup and view all the answers

    What mechanism is responsible for the amplification of oxytocin release during childbirth?

    <p>A positive feedback loop involving uterine contractions and oxytocin release. (D)</p> Signup and view all the answers

    What type of tissue is the anterior pituitary mainly composed of?

    <p>Endocrine cells (B)</p> Signup and view all the answers

    Which of the following describes the primary relationship between the hypothalamus and the posterior pituitary?

    <p>Hypothalamic neurons directly project into the posterior pituitary to release hormones. (C)</p> Signup and view all the answers

    Hormone release from the anterior pituitary is controlled by:

    <p>The hypothalamic-portal system. (A)</p> Signup and view all the answers

    Which of the following hormones is primarily associated with the posterior pituitary?

    <p>Oxytocin (C)</p> Signup and view all the answers

    What did Dale's experiments with pituitary extract demonstrate?

    <p>It caused uterine contractions and promoted milk release. (B)</p> Signup and view all the answers

    By 1911, what was the primary medical application of pituitary extracts?

    <p>To induce contractions during labor. (A)</p> Signup and view all the answers

    Which part of the brain is primarily involved in stimulating the release of oxytocin during lactation?

    <p>The hypothalamus. (A)</p> Signup and view all the answers

    Which of the following is the major stimulus for the release of oxytocin?

    <p>The sucking of an infant. (C)</p> Signup and view all the answers

    What is the primary function of myoepithelial cells in the mammary gland during lactation?

    <p>To contract and promote milk ejection. (C)</p> Signup and view all the answers

    What is the direct effect of oxytocin on the mammary gland?

    <p>It promotes milk ejection. (B)</p> Signup and view all the answers

    Sensory receptors in the nipple connect to nerve fibers that directly relay impulses to which location?

    <p>The spine. (B)</p> Signup and view all the answers

    Besides milk ejection, what other function is associated with pituitary extracts?

    <p>Regulation of sodium excretion. (D)</p> Signup and view all the answers

    Which of these is a hormone that is NOT secreted directly by the pituitary gland, but rather stimulates another gland?

    <p>Adrenocorticotropic Hormone (ACTH) (A)</p> Signup and view all the answers

    Disruption of the pituitary gland can lead to secondary Addison's disease. Which of the following sequences describes the pathway of hormones involved in this disorder?

    <p>Pituitary gland -&gt; ACTH -&gt; Adrenal Cortex -&gt; Cortisol (B)</p> Signup and view all the answers

    If a patient is diagnosed with Central Diabetes Insipidus, which of the following hormones is most likely to be deficient or improperly regulated?

    <p>Antidiuretic Hormone (ADH) (A)</p> Signup and view all the answers

    Which of the following best describes the hypothalamic-pituitary axis?

    <p>A hormonal cascade where the hypothalamus controls hormone release from the pituitary gland, which in turn regulates other endocrine glands. (D)</p> Signup and view all the answers

    What type of feedback loop primarily regulates hormone secretion within the hypothalamic-pituitary axis?

    <p>Negative feedback loops (A)</p> Signup and view all the answers

    Which of the following hormones are secreted by the posterior pituitary?

    <p>Oxytocin and Anti-diuretic Hormone (ADH) (A)</p> Signup and view all the answers

    Which of the following pituitary hormones is essential for normal growth and development?

    <p>Growth hormone (GH) (A)</p> Signup and view all the answers

    A patient presents with symptoms of acromegaly, an endocrine disorder characterized by abnormal bone growth. Dysfunction of which of the following hormones is most likely to cause this condition?

    <p>Growth Hormone (GH) (D)</p> Signup and view all the answers

    In the context of milk ejection, what type of feedback system is formed by oxytocin secretion in response to suckling?

    <p>Open loop feedback system (C)</p> Signup and view all the answers

    What is the primary function of ADH in relation to water balance?

    <p>To increase water permeability in the distal tubules and collecting ducts. (C)</p> Signup and view all the answers

    What is the direct consequence of ADH promoting vasoconstriction?

    <p>Increased blood pressure (A)</p> Signup and view all the answers

    What are the key factors that stimulate the secretion of ADH?

    <p>Low blood volume and high plasma osmolarity. (A)</p> Signup and view all the answers

    Compared to the pig hormone, what amino acid difference defines human Arginine Vasopressin (AVP)?

    <p>Arginine instead of lysine at position 8. (A)</p> Signup and view all the answers

    How does ADH affect urine concentration when acting on the kidneys?

    <p>It increases urine osmolality and decreases urine volume. (D)</p> Signup and view all the answers

    During labor, what causes increased oxytocin secretion?

    <p>Increased cervical stretch. (A)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of ADH (Vasopressin)?

    <p>It is identical to Oxytocin. (D)</p> Signup and view all the answers

    Which of these receptor subtypes, when activated, leads to an increase in intracellular cAMP levels?

    <p>AVPR2 (C)</p> Signup and view all the answers

    Where is the AVPR2 receptor primarily located, according to the text?

    <p>Kidney tubules and collecting duct (A)</p> Signup and view all the answers

    What is the primary function of aquaporin-2 channels in kidney cells, as described in the text?

    <p>Water reabsorption (D)</p> Signup and view all the answers

    Which of the following accurately describes the mechanism by which ADH increases water reabsorption in the kidney?

    <p>ADH activates adenylate cyclase, increasing cAMP, leading to aquaporin-2 insertion. (B)</p> Signup and view all the answers

    What effect does an increased blood osmolality have on ADH secretion?

    <p>Increase ADH secretion (B)</p> Signup and view all the answers

    How would a decrease in blood volume affect ADH secretion?

    <p>Increase ADH secretion (A)</p> Signup and view all the answers

    What is the main effect of ADH on the kidney?

    <p>Increase water reabsorption (A)</p> Signup and view all the answers

    All ADH receptors are coupled to which type of protein?

    <p>G-coupled receptors (B)</p> Signup and view all the answers

    Study Notes

    Pituitary Gland Overview

    • The pituitary gland is a small gland located at the base of the brain.
    • It has two major components: the anterior lobe (adenohypophysis) and the posterior lobe (neurohypophysis).
    • The pituitary is part of the hypothalamic-pituitary axis (HPA), a critical component regulating hormone secretion from various endocrine glands.
    • Pituitary gland function disruption can trigger various endocrine disorders.

    Pituitary Gland Anatomy

    • The gland is located within the sella turcica of the sphenoid bone.
    • The infundibulum (stalk) connects the pituitary to the brain.
    • The posterior lobe is an extension of the neural tissue.
    • The anterior lobe is an epithelial gland of true endocrine origin.
    • The graphic displays the pars tuberalis, neurohypophysis, infundibular stalk, median eminence, adenohypophysis, pars distalis, pars nervosa, and pars intermedia.

    Pituitary Gland Development

    • The pituitary gland emerges from two embryonic sources.
    • The posterior lobe arises from the diencephalon's neuroepithelium.
    • The anterior lobe (and intermediate lobe) arises from an out-pocketing of epithelial cells called Rathke's pouch in the oral cavity.

    Pituitary Gland Hormones (Posterior Pituitary)

    • The posterior pituitary (PN2) stores and secretes two hormones: oxytocin and antidiuretic hormone (ADH, also called vasopressin).
    • Oxytocin:
      • Targets uterine muscles and mammary glands.
      • Plays a role in labor contractions and milk ejection.
    • Antidiuretic Hormone (ADH):
      • Targets kidney tubules.
      • Regulates water balance by controlling the kidneys' water reabsorption.
      • Elevates in response to dehydration and reduced blood volume/pressure.

    Pituitary Gland Hormones (Posterior Pituitary) Production

    • Oxytocin and ADH are synthesized in the hypothalamus.
    • These hormones are stored in axon terminals (Herring bodies) within the posterior pituitary.
    • Release is triggered by action potentials, which then enter circulation.

    Pituitary Gland Hormone Release Stimulation

    • Sensory input from neural receptors stimulates hormone release.
    • For example, suckling in the mammary glands triggers oxytocin release.
    • Cervical and uterine reflexes stimulate oxytocin release during childbirth.

    Positive Feedback Control of Oxytocin

    • Positive feedback mechanisms amplify oxytocin release during childbirth, vital for uterus contractions.

    Antidiuretic Hormone (ADH) - Function

    • ADH regulates water balance by influencing kidney function.
    • ADH increases water permeability in the kidney tubules and collection ducts.
    • This effect conserves water in the body and concentrates urine.
    • Higher concentrations of ADH stimulate vasoconstriction to raise blood pressure.

    Factors Promoting ADH Secretion

    • Higher plasma osmolarity triggers ADH release, while lower blood volume/pressure also stimulates ADH release.

    ADH Receptors

    • ADH has different receptor subtypes (e.g., V2 receptors).
    • These receptors influence water reabsorption by targeting kidney tubules and initiate water retention and concentrated urine output.

    Diabetes Insipidus (DI)

    • DI involves disruptions in either ADH levels or response to ADH, causing problems with water balance.
    • There are three main types:
      • Pituitary/Central DI: insufficient ADH production.
      • Nephrogenic DI: kidneys unresponsive to ADH.
      • Dipsogenic DI: excessive fluid intake.
      • Major symptoms include excessive thirst and excretion of large volumes of dilute urine.

    Diagnostic Analysis for DI

    • Blood tests evaluate glucose and electrolyte levels (e.g., hypernatremia).
    • Urine tests assess osmolarity and specific gravity (low, dilute).
    • A fluid deprivation test helps distinguish the causes of DI.

    Causes of DI

    • Pituitary DI: deficiencies in ADH production, pituitary tumor, head injury, infection.
    • Nephorgenic DI: genetic defects, certain drugs (e.g., lithium), kidney diseases (e.g., polycystic).
    • Dipsogenic DI: excessive fluid intake, defect in thirst regulation.

    Learning Objectives

    • Key differences between posterior and anterior pituitary, and the related tissues.
    • Understanding of hypothalamic/pituitary regulation of hormone synthesis/secretion.
    • Hormone secretion feedback control.
    • Posterior pituitary gland hormones and their functions.
    • Effects of disruptions in pituitary function leading to specific endocrine disorders (e.g., DI).

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    The Pituitary Gland - 2025 PDF

    Description

    Explore the structure and functionality of the pituitary gland in this comprehensive quiz. Learn about its components, location, and role in the endocrine system. Understand how disruptions in pituitary function can lead to various disorders.

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