Thyroxine-binding Proteins in the Plasma
62 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of the thyroid gland?

  • Control heart rate
  • Regulate blood sugar levels
  • Produce insulin
  • Secrete thyroid hormones to maintain metabolism (correct)
  • What are the consequences of hypothyroidism in adults?

  • Body wasting and poor resistance to cold (correct)
  • Excess heat production
  • Severe mental retardation
  • Tachycardia
  • What hormone controls the function of the thyroid gland?

  • Estrogen
  • Adrenaline
  • Insulin
  • Thyroid-stimulating hormone (TSH) (correct)
  • What is a consequence of excess thyroid secretion?

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

    Which protein binds most of the circulating T4?

    <p>Thyroxine-binding globulin (TBG)</p> Signup and view all the answers

    What is the half-life of transthyretin?

    <p>2 days</p> Signup and view all the answers

    How much of the circulating T3 is formed by deiodination of T4?

    <p>87%</p> Signup and view all the answers

    What serves to catabolize the thyroid hormones T4 and T3?

    <p>Liver, kidneys, and many other tissues</p> Signup and view all the answers

    What is the primary regulator of thyroid function?

    <p>Pituitary TSH</p> Signup and view all the answers

    Which hormone inhibits TSH secretion in a negative feedback manner?

    <p>Free T4</p> Signup and view all the answers

    What happens to the thyroid gland with prolonged TSH stimulation?

    <p>Cells hypertrophy</p> Signup and view all the answers

    What is the term used to describe enlargement of the thyroid gland?

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

    What is the main function of the thyroid gland?

    <p>To secrete calcitonin</p> Signup and view all the answers

    How is thyroglobulin secreted into the colloid?

    <p>By exocytosis of granules</p> Signup and view all the answers

    What enzyme mediates the oxidation and reaction of iodide with thyroglobulin?

    <p>Thyroid peroxidase</p> Signup and view all the answers

    How does the secretion of thyroid hormone get controlled?

    <p>By negative feedback control from high thyroid hormone levels</p> Signup and view all the answers

    Which protein has the smallest capacity to bind T4 in plasma?

    <p>Thyroxine-binding globulin (TBG)</p> Signup and view all the answers

    What is the approximate daily secretion of T3 by the human thyroid in nmol?

    <p>7</p> Signup and view all the answers

    In plasma, what is the approximate level of total T4 in adults in nmol/L?

    <p>103</p> Signup and view all the answers

    Which type of thyroid hormones are considered physiologically active in plasma?

    <p>Free forms</p> Signup and view all the answers

    What is the mechanism of action of propylthiouracil and methimazole in treating hyperthyroidism?

    <p>Inhibit the iodination of tyrosine by competing for iodine</p> Signup and view all the answers

    Which compound is responsible for reducing the conversion of T4 to T3 in extrathyroidal tissues?

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

    What is the treatment approach for severe cases of hyperthyroidism that leads to partial destruction of the thyroid gland?

    <p>Infusion of radioactive iodine</p> Signup and view all the answers

    Why does Hashimoto thyroiditis initially present with excess thyroid hormone secretion and thyrotoxicosis?

    <p>Inflammation causes excess thyroid hormone secretion</p> Signup and view all the answers

    What is the main mechanism by which thyroid hormones exert their effects?

    <p>Entering cells and binding to nuclear receptors</p> Signup and view all the answers

    What are the primary physiological effects of thyroid hormones in the body?

    <p>Increasing metabolic rate and cardiac function</p> Signup and view all the answers

    What are the consequences of hypothyroidism in neonatal life?

    <p>Mental retardation and dwarfism</p> Signup and view all the answers

    What effect does an increased proportion of α-myosin heavy chain have on the heart?

    <p>Increased ATPase activity</p> Signup and view all the answers

    Which tissue experiences a catabolic effect due to stimulated lipolysis?

    <p>Adipose tissue</p> Signup and view all the answers

    What is the metabolic effect on the gut as a result of thyroid hormone action?

    <p>Increased rate of carbohydrate absorption</p> Signup and view all the answers

    Which tissue benefits from the promotion of normal growth and skeletal development by thyroid hormones?

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

    What is the primary hormone responsible for regulating thyroid function?

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

    What is the consequence of prolonged TSH stimulation on the thyroid gland?

    <p>Thyroid atrophy</p> Signup and view all the answers

    Which hormone inhibits TSH secretion as part of a negative feedback mechanism?

    <p>T4</p> Signup and view all the answers

    What is the syndrome of adult hypothyroidism generally called?

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

    Which protein has the smallest capacity to bind T4 in plasma?

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

    What is the approximate daily secretion of RT3 by the human thyroid in nmol?

    <p>3.5 nmol</p> Signup and view all the answers

    Which compound is responsible for reducing the conversion of T4 to T3 in extrathyroidal tissues?

    <p>RT3</p> Signup and view all the answers

    What is the normal total plasma T3 level in adults approximately?

    <p>0.15 μg/dL (2.3 nmol/L)</p> Signup and view all the answers

    What is the recommended treatment approach for addressing iodide deficiency in developed countries?

    <p>Adding iodized salt to the diet</p> Signup and view all the answers

    In cases of congenital hypothyroidism, what synthetic form of the thyroid hormone is typically given?

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

    What are the characteristic symptoms of hyperthyroidism?

    <p>Nervousness and weight loss</p> Signup and view all the answers

    What is the primary factor determining the severity of mental deficiency in cases of iodine deficiency during pregnancy?

    <p>The mother's thyroid condition</p> Signup and view all the answers

    What effect does an increased rate of carbohydrate absorption in the gut as a result of thyroid hormone action have on metabolism?

    <p>Enhancing calorigenesis</p> Signup and view all the answers

    How do thyroid hormones primarily influence the heart's function?

    <p>By enhancing responses to circulating catecholamines</p> Signup and view all the answers

    What is the main regulatory hormone responsible for stimulating the synthesis and secretion of thyroid hormones?

    <p>Thyroid-stimulating hormone (TSH)</p> Signup and view all the answers

    Which tissue is negatively affected by an increased metabolic rate due to stimulated oxygen consumption as a result of thyroid hormone action?

    <p>Adipose tissue</p> Signup and view all the answers

    Thyroid peroxidase is not involved in the coupling as well as iodination of thyroid hormones.

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

    In the normal human thyroid, the average distribution of iodinated compounds is 3% MIT, 33% DIT, 35% T4, and 7% T3.

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

    RT3 is formed by condensation of two DIT molecules.

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

    T3 is formed by condensation of MIT with DIT.

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

    Hypothyroidism can only be caused by diseases of the thyroid gland.

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

    When dietary iodine intake is inadequate, the thyroid hypertrophies.

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

    Drugs can never inhibit thyroid function.

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

    Iodide itself never inhibits thyroid function.

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

    Graves disease is the most common cause of hypothyroidism.

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

    Antibodies to the TSH receptor stimulate the receptor in Graves disease.

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

    Plasma TSH levels are typically high in patients with Graves disease.

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

    Exophthalmos is a common symptom of Graves disease.

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

    Thyroid hormones only exert their effects by binding to thyroid receptors on the cell membrane.

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

    Hypothyroidism in neonatal life can lead to mental retardation and dwarfism.

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

    Overactivity of the thyroid gland caused by autoantibodies may result in body wasting, nervousness, and bradycardia.

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

    More Like This

    Intracellular Signaling and Cell Membrane
    60 questions
    Hormone Binding Proteins
    25 questions

    Hormone Binding Proteins

    InstrumentalDoppelganger avatar
    InstrumentalDoppelganger
    Use Quizgecko on...
    Browser
    Browser