Pituitary Gland Overview
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Questions and Answers

What is the primary function of the anterior pituitary gland?

  • Regulate blood pressure
  • Control the majority of endocrine glands (correct)
  • Produce insulin
  • Store calcium

    • Which hormone is secreted by somatotropes?

  • Thyroid stimulating hormone (TSH)
  • Growth hormone (correct)
  • Prolactin
  • Adrenocorticotrophic hormone (ACTH)

    • What type of feedback mechanism is most common in the endocrine system?

  • Ultra short loop feedback
  • Positive feedback
  • Negative feedback (correct)
  • Short loop feedback

    • Which hormone's levels would be decreased in response to high levels of growth hormone?

    <p>Growth Hormone Inhibitory Hormone (GIH)</p> Signup and view all the answers

    What is the role of prolactin inhibitory hormone (PIH)?

    <p>Inhibit the release of prolactin</p> Signup and view all the answers

    Which hormone is secreted by the gonadotropes?

    <p>Follicle stimulating hormone (FSH)</p> Signup and view all the answers

    Which type of feedback encourages the endocrine gland to increase hormone secretion?

    <p>Positive feedback</p> Signup and view all the answers

    What is the function of Thyrotropine Releasing Hormone (TRH)?

    <p>Stimulate thyroid stimulating hormone release</p> Signup and view all the answers

    What effect does growth hormone (GH) have on carbohydrate metabolism?

    <p>It stimulates gluconeogenesis and glycogenolysis.</p> Signup and view all the answers

    Which factor is NOT known to increase growth hormone secretion?

    <p>Excessive cortisol levels</p> Signup and view all the answers

    What characterizes pituitary dwarfism due to GH deficiency?

    <p>Height equal to span between outstretched fingers</p> Signup and view all the answers

    What hormone inhibits the production of growth hormone from the anterior pituitary?

    <p>Growth hormone inhibiting hormone (GHIH)</p> Signup and view all the answers

    What is the result of excess GH secretion after epiphyseal closure?

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

    What condition is characterized by a deficiency of all anterior pituitary hormones?

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

    Which change is NOT associated with premature senility due to panhypopituitarism?

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

    Which action does GH NOT typically perform in terms of mineral retention?

    <p>Increases sodium and potassium excretion</p> Signup and view all the answers

    What is the primary action of Growth Hormone (GH) on the skeleton?

    <p>Stimulate hypertrophy and hyperplasia</p> Signup and view all the answers

    What effect does cortisol have in the context of long loop feedback?

    <p>Suppresses CRF from the hypothalamus</p> Signup and view all the answers

    Which of the following statements about somatomedins is correct?

    <p>The principal circulating somatomedin is IGF-I</p> Signup and view all the answers

    What is a significant factor that can decrease the levels of somatomedins?

    <p>Untreated diabetes</p> Signup and view all the answers

    What action does Growth Hormone have on protein metabolism?

    <p>It acts as an anabolic agent</p> Signup and view all the answers

    Which of the following describes the effect of estrogen in feedback mechanisms?

    <p>Acts to stimulate further production of LH</p> Signup and view all the answers

    Which of the following factors is NOT associated with an increased level of Growth Hormone?

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

    What is the average level of Growth Hormone in adults over a 24-hour period?

    <p>2-4 ng</p> Signup and view all the answers

    What effect does high levels of prolactin have on the secretion of prolactin?

    <p>It inhibits prolactin secretion.</p> Signup and view all the answers

    What is a common effect of hyperprolactinemia in females?

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

    Which hormone is released by the posterior pituitary?

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

    What is the primary action of ADH in renal physiology?

    <p>Facilitate water reabsorption</p> Signup and view all the answers

    What is the effect of dopamine antagonists on prolactin secretion?

    <p>They stimulate prolactin secretion.</p> Signup and view all the answers

    What role does vasopressin play in the vascular system?

    <p>It causes vasoconstriction in large doses.</p> Signup and view all the answers

    How does stress affect prolactin levels?

    <p>It stimulates a rise in prolactin levels.</p> Signup and view all the answers

    Which type of receptor is NOT associated with ADH?

    <p>V4</p> Signup and view all the answers

    What is the primary function of oxytocin during lactation?

    <p>Contracts myoepithelial cells around breast alveoli</p> Signup and view all the answers

    Which factor would most likely result in an increase in ADH secretion?

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

    What effect does stress have on ADH levels?

    <p>It stimulates ADH through the CRH-ADH system</p> Signup and view all the answers

    What is a key symptom of diabetes insipidus?

    <p>Low specific gravity of urine</p> Signup and view all the answers

    How does oxytocin aid during labor?

    <p>By contracting the myometrium to expel the baby</p> Signup and view all the answers

    What is the effect of hot weather on ADH secretion?

    <p>Increases ADH secretion due to dehydration</p> Signup and view all the answers

    Which of the following describes a mechanism for increased ADH secretion?

    <p>Stimulation of osmoreceptors by increased plasma osmolarity</p> Signup and view all the answers

    What effect does morphine have on ADH secretion?

    <p>It stimulates ADH secretion</p> Signup and view all the answers

    Study Notes

    Pituitary Gland Overview

    • Small gland measuring 1 cm in diameter, located in the sella turcica.
    • Connected to the hypothalamus via the pituitary stalk.
    • Divided into anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis).

    Anterior Pituitary (Adenohypophysis) Functions

    • Acts as the master gland for most endocrine functions.
    • Regulates thyroid glands, adrenal cortex, and gonads.

    Hormones Secreted by Anterior Pituitary

    • Growth Hormone (GH) - secreted by somatotropes (acidophils).
    • Prolactin (PRL) - secreted by mammotropes (acidophils).
    • Thyroid Stimulating Hormone (TSH) - secreted by thyrotropes (basophils).
    • Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) - secreted by gonadotropes (basophils).
    • Adrenocorticotropic Hormone (ACTH) - secreted by corticotropes (basophils).

    Regulation of Anterior Pituitary

    • Controlled by hypothalamic releasing and inhibiting factors.
    • Releasing factors: TRH, FRH, LHRH, CRH, GH releasing hormone (GRH).
    • Inhibitory factors: Somatostatin (GH inhibitory hormone), Prolactin inhibitory hormone (PIH).

    Feedback Mechanisms

    • Negative feedback: Hormonal levels in blood regulate secretion levels; high levels lead to decreased secretion.
    • Short, long, and ultra short loops describe feedback mechanisms influencing different glands.
    • Positive feedback: Less common, such as increased estrogen leading to more LH secretion.

    Growth Hormone (GH)

    • Polypeptide hormone with an average secretion of 5-8 ng/24 hours in children and 2-4 ng in adults.
    • Functions: Stimulates cell growth (hypertrophy) and division (hyperplasia); increases mineral retention; promotes protein synthesis.

    Somatomedins

    • Polypeptides secreted mainly by the liver, mediating GH effects.
    • Insulin-like Growth Factor I (IGF-I) and Insulin-like Growth Factor II (IGF-II) are key somatomedins.
    • Factors decreasing somatomedins include protein deficiency and untreated diabetes.

    Disorders of Anterior Pituitary

    • Deficiency Conditions:
      • Pituitary dwarfism: Characterized by arrested skeletal growth.
      • Pituitary infantilism: Deficiency of GH and gonadotropins causing hypogonadism.
      • Panhypopituitarism: Loss of all hormone functions leading to premature aging signs.
    • Excess Conditions:
      • Gigantism: Excess GH before epiphysis closure.
      • Acromegaly: Excess GH after epiphysis closure.

    Posterior Pituitary Overview

    • Secretes Vasopressin (ADH) and Oxytocin.
    • Hormones are synthesized in the hypothalamus and stored in the pituitary.

    Antidiuretic Hormone (ADH) Function

    • Regulates water reabsorption in kidneys via V2 receptors.
    • Increases blood pressure through vasoconstriction in large doses via V1 receptors.
    • Release is stimulated by increased plasma osmolarity and hypovolemia.

    Diabetes Insipidus

    • Caused by ADH deficiency leading to polyuria and polydipsia.
    • Nephrogenic diabetes insipidus results from a lack of kidney response to ADH.

    Oxytocin Functions

    • Important for milk ejection during breastfeeding and uterine contractions during labor.
    • Involves neurohormonal reflexes triggered by suckling and cervical dilation during labor.

    Control of Oxytocin and ADH

    • Oxytocin levels rise during suckling and labor due to reflex triggers.
    • ADH levels are influenced by osmolarity, blood volume status, stress, and certain drugs.

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    Physiology Lec 2,3 NEW Pituitary PDF

    Description

    Test your knowledge on the anatomy and function of the pituitary gland, commonly known as the hypophysis. This quiz covers the different parts of the pituitary gland, including the anterior and posterior pituitary lobes, and their roles in the endocrine system.

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