Thyroid Hormone Physiology Review
45 Questions
0 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 predominant form of thyroid hormone secreted by the thyroid gland?

  • T2 (Diiodothyronine)
  • T1 (Monoiodothyronine)
  • T4 (Thyroxine) (correct)
  • T3 (Triiodothyronine)
  • Which form of thyroid hormone is considered more biologically active?

  • T4 (Thyroxine)
  • T3 (Triiodothyronine) (correct)
  • T1 (Monoiodothyronine)
  • T2 (Diiodothyronine)
  • How do thyroid hormones primarily affect cellular processes?

  • By directly modifying DNA structure
  • By reducing metabolic activity
  • By influencing transcription processes (correct)
  • By inhibiting protein synthesis
  • What is the effect of thyroid hormones on metabolic rate?

    <p>They increase the metabolic rate.</p> Signup and view all the answers

    What role do thyroid hormones play in the development of the nervous system?

    <p>They are crucial for normal development and function.</p> Signup and view all the answers

    Which hormone is released by the hypothalamus to stimulate the production of TSH?

    <p>TRH (Thyrotropin-releasing hormone)</p> Signup and view all the answers

    What hormone is produced by the anterior pituitary gland and stimulates thyroid hormone release?

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

    What is the relationship between T4 and T3 in the body?

    <p>T4 is gradually converted into T3.</p> Signup and view all the answers

    What is the primary cause of primary hyperthyroidism?

    <p>Genetic mutations affecting TSH receptor</p> Signup and view all the answers

    How does the body respond when T3 and T4 levels are elevated?

    <p>TSH and TRH secretion decreases</p> Signup and view all the answers

    What is a potential consequence of toxic nodular or multinodular goiter?

    <p>Excessive thyroid hormone production</p> Signup and view all the answers

    What condition describes the autoimmune stimulation of the thyroid gland?

    <p>Graves Disease</p> Signup and view all the answers

    In secondary hyperthyroidism, what causes the increase in thyroid hormone production?

    <p>TSH-secreting pituitary adenomas</p> Signup and view all the answers

    What is a characteristic feature of thyroid adenomas?

    <p>They are benign tumors</p> Signup and view all the answers

    What results from an overdose of thyroid medication?

    <p>Thyrotoxicosis leading to hyperthyroidism</p> Signup and view all the answers

    Which term describes inflammation of the thyroid gland that sometimes develops after childbirth?

    <p>Postpartum thyroiditis</p> Signup and view all the answers

    What is the main cause of secondary hyperthyroidism?

    <p>Excessive TSH production from the pituitary gland</p> Signup and view all the answers

    Which of the following is a consequence of increased T3 and T4 levels in the body?

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

    What role do thyroid stimulating immunoglobulins (TSI) play in Graves' disease?

    <p>They mimic TSH and stimulate thyroid hormone production.</p> Signup and view all the answers

    What is a common clinical feature associated with secondary hyperthyroidism?

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

    Which symptom is specifically related to increased stimulation of the sympathetic nervous system (SNS)?

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

    How does high T3 and T4 levels affect TSH production in the pituitary gland?

    <p>They suppress TSH production.</p> Signup and view all the answers

    What is a major consequence of increased neuromuscular activity associated with elevated thyroid hormones?

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

    What is a potential consequence of abrupt medication cessation related to hypocortisolism?

    <p>Temporary hypocortisolism leading to adrenal dysfunction</p> Signup and view all the answers

    What can result from aldersterone deficiency?

    <p>Inability to conserve sodium and water, leading to low blood pressure</p> Signup and view all the answers

    Which of the following is NOT a consequence mentioned for hyperthyroidism?

    <p>Increased hair growth</p> Signup and view all the answers

    Which symptom indicates increased ACTH in primary hypocortisolism?

    <p>Hyperpigmentation of the skin</p> Signup and view all the answers

    Hypocortisolism can lead to which of the following clinical issues?

    <p>Decreased sympathetic nervous system activity</p> Signup and view all the answers

    What is a primary cause of secondary hypocortisolism?

    <p>Underactive pituitary gland producing less ACTH</p> Signup and view all the answers

    What is one of the effects of increased cortisol levels on the body?

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

    What physical change is commonly associated with excessive cortisol production?

    <p>Buffalo hump on the upper back</p> Signup and view all the answers

    Which condition is characterized by a lack of sufficient cortisol production from the adrenal glands?

    <p>Addison disease</p> Signup and view all the answers

    What can increased levels of ACTH lead to in terms of skin appearance?

    <p>Hyperpigmentation of skin</p> Signup and view all the answers

    What is caused by the autoimmune destruction of the adrenal cortex?

    <p>Primary hypocortisolism</p> Signup and view all the answers

    Which of the following conditions is primarily linked to pituitary gland dysfunction?

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

    What happens to ACTH production when a person is taking exogenous glucocorticoids?

    <p>ACTH production is suppressed</p> Signup and view all the answers

    What is one possible effect of excessive ACTH levels in women?

    <p>Hirsutism or excessive hair growth</p> Signup and view all the answers

    What is one of the primary contributors to the degeneration of extraocular muscles in Graves' disease?

    <p>Continuous stimulation of the thyroid gland by TSI</p> Signup and view all the answers

    Which condition is associated with a congenital lack of thyroid tissue?

    <p>Primary hypothyroidism</p> Signup and view all the answers

    What is the consequence of iodine deficiency on thyroid function?

    <p>Impaired production of thyroid hormones</p> Signup and view all the answers

    Which of the following is a rare condition affecting the pituitary gland after childbirth?

    <p>Postpartum pituitary necrosis</p> Signup and view all the answers

    What is the primary effect of primary hypothyroidism on thyroid hormone levels?

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

    Which of the following mechanisms is NOT a cause of secondary hypothyroidism?

    <p>Iodine deficiency</p> Signup and view all the answers

    What is a characteristic symptom of Graves' disease affecting ocular tissue?

    <p>Protrusion of the eyeballs</p> Signup and view all the answers

    Which autoimmune disease is characterized by the immune system attacking the thyroid gland?

    <p>Hashimoto's thyroiditis</p> Signup and view all the answers

    Study Notes

    Thyroid Hormone - Physiology Review

    • Thyroid hormones, T3 and T4, are produced by follicle cells in the thyroid gland.
    • T4 is the dominant form, accounting for 90% of secreted thyroid hormone.
    • T4 has a longer half-life than T3.
    • Initially, T4 is more abundant, but it's converted to T3 as it travels to target cells.
    • T3 is the more biologically active form, having a stronger effect on metabolic processes.

    Physiological Effects

    • Thyroid hormones regulate protein production by influencing transcription.
    • They stimulate the body's metabolic rate, speeding up chemical reactions for energy production.

    Feedback and Regulation of T3/T4

    • TRH (Thyrotropin-releasing hormone) from the hypothalamus triggers TSH (Thyroid-stimulating hormone) release from the anterior pituitary gland.
    • TSH stimulates thyroid function, increasing T3 and T4 production, follicle growth, and gland size.
    • High levels of T3 and T4 in the bloodstream inhibit TRH and TSH release, maintaining a healthy range of hormone levels. This is a negative feedback loop.

    TRH and TSH

    • TRH (Thyrotropin-releasing hormone) is secreted by the hypothalamus.
    • TSH (Thyroid-stimulating hormone) is produced by the anterior pituitary gland.
    • TSH acts directly on the thyroid gland to promote T3 and T4 production.

    Hyperthyroidism

    • Hyperthyroidism is when the body's tissues are exposed to excessive thyroid hormone.
    • Causes of hyperthyroidism include primary problems in the thyroid gland itself or secondary problems due to excessive TSH release from the anterior pituitary.
    • Common causes include: genetic predisposition, thyroiditis, toxic nodular or multinodular goiter, thyroid adenomas, or thyroid cancer.

    Pathophysiology of Hyperthyroidism

    • Primary hyperthyroidism: The thyroid gland is overly active, leading to increased T3 and T4 production, and TSH suppression (negative feedback).
    • Secondary hyperthyroidism: An overactive pituitary gland releases excessive TSH, stimulating the thyroid to produce excess T3 and T4.

    Clinical Consequences of Hyperthyroidism

    • Increased metabolic rate, leading to weight loss, heat intolerance, and increased energy expenditure.
    • Increased neuromuscular activity: tremors, restlessness, rapid heartbeat, and anxiety.
    • Increased SNS (sympathetic nervous system) activity: rapid heartbeat, increased blood pressure, anxiety, and excessive sweating.
    • Goiter: An enlarged thyroid gland, often associated with secondary hyperthyroidism, caused by the consistent stimulation.

    Graves' Disease

    • An autoimmune disorder where the body mistakenly attacks the thyroid gland, producing antibodies (TSI) mimicking TSH's actions.
    • TSI overproduction leads to overstimulation of the thyroid gland, increased T3 and T4 production, and suppressed TSH levels.
    • Clinical consequences include symptoms of hyperthyroidism, such as: Increased metabolic rate, tremors, rapid heartbeat, and anxiety, along with specific symptoms like goiter or vision issues (exophthalmos and ocular tissue issues).

    Hypothyroidism

    • Hypothyroidism occurs when the thyroid gland isn't functioning properly, resulting in low levels of T3 and T4.
    • Causes include loss of thyroid tissue, iodine deficiency, congenital lack of thyroid tissue, Hashimoto's thyroiditis and secondary hypothyroidism.

    Primary Hypothyroidism

    • Problems originating in the thyroid gland itself, such as loss of thyroid tissue, iodine deficiency, or congenital lack of thyroid tissue.

    Hashimoto's Thyroiditis

    • An autoimmune condition where the immune system attacks the thyroid gland, decreasing hormone production.

    Secondary Hypothyroidism

    • Problems within the pituitary gland, such as pituitary tumor, stroke to hypothalamus or pituitary, or postpartum pituitary necrosis.

    Clinical Consequences of Hypothyroidism

    • Decreased metabolic rate, leading to weight gain, fatigue, cold intolerance, and slowness of movement.
    • Decreased neuromuscular activity: generalized fatigue, decreased reflexes and slowness of movements.
    • Decreased SNS activity: reduced heart rate, blood pressure, along with potential depression.
    • Myxedema: swelling due to water retention in tissues.

    Cortisol - Physiology Review

    • Cortisol, the primary glucocorticoid, regulates glucose metabolism and has anti-inflammatory effects, crucial for survival during stress.
    • Cortisol is secreted by the adrenal cortex, located near the kidneys.

    Physiological Effects of Cortisol

    • Cortisol regulates glucose metabolism.
    • It elevates blood glucose levels through decreasing glucose uptake in tissues and increasing gluconeogenesis.
    • It promotes protein breakdown in muscles and collagen; this provides amino acids for gluconeogenesis.
    • It stimulates fat breakdown and promotes fat deposition in the face and trunk.
    • It suppresses the immune response.

    Feedback and Regulation of Cortisol

    • The hypothalamus releases CRH (corticotropin-releasing hormone).
    • CRH stimulates ACTH (adrenocorticotropic hormone) release from the anterior pituitary gland.
    • ACTH stimulates cortisol production by the adrenal cortex.
    • High cortisol levels inhibit CRH and ACTH release (negative feedback).

    Hypercortisolism

    • Excess cortisol in the body, caused by primary adrenal cortex overactivity (Cushing syndrome) or secondary pituitary gland overactivity (Cushing disease).
    • Causes can also include ectopic production from other tumors.
    • Etiologies: includes adrenal adenomas and carcinomas, non-adrenal tumors, and cortisol-like medications like hydrocortisone and prednisone.

    Pathophysiology of Hypercortisolism

    • Primary hypercortisolism: The adrenal cortex produces too much cortisol, and ACTH levels are usually suppressed.
    • Secondary hypercortisolism: The pituitary gland excessively releases ACTH encouraging the adrenal cortex to produce excessive cortisol.

    Clinical Consequences of Hypercortisolism

    • Hyperglycemia, weight gain (especially in the face and trunk), thinning extremities, muscle weakness, skin changes, and osteoporosis, blood pressure increase, and increased susceptibility to infections.
    • Increased SNS (sympathetic nervous system) activity leading to symptoms like increased heart rate, blood pressure, and anxiety.

    Hypocortisolism (Addison Disease)

    • Insufficient cortisol production by the adrenal cortex.
    • This can be due to adrenal cortex atrophy, destruction (e.g., autoimmune destruction), or issues with the anterior pituitary.
    • Pathophysiology differs in primary and secondary hypocortisolism
    • Primary hypocortisolism is adrenal-based: decreased cortisol production due to adrenal cortex damage.
    • Secondary hypocortisolism is pituitary-based: insufficient ACTH (anterior pituitary hormone) leading to reduced cortisol production.

    Clinical Consequences of Hypocortisolism

    • Hypoglycemia, decreased SNS activity (low blood pressure, reduced heart rate), and dehydration.
    • Also includes impaired functioning of the kidneys in relation to sodium and water retention and processing.
    • Hyperpigmentation, sometimes in creases and areas exposed to the sun or high friction.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Description

    This quiz reviews the physiology of thyroid hormones, focusing on the roles of T3 and T4 in the body. Learn about their production, physiological effects, and the feedback regulation mechanism that maintains hormonal balance. Ideal for students looking to understand endocrine system functions.

    More Like This

    The Thyroid Hormones Quiz
    15 questions

    The Thyroid Hormones Quiz

    UnbiasedRooster7856 avatar
    UnbiasedRooster7856
    Thyroid Hormones T3 and T4 Functions
    40 questions
    Biosynthesis of T4 and T3 Hormones
    8 questions
    Thyroid Gland and Hormones Quiz
    68 questions
    Use Quizgecko on...
    Browser
    Browser