Acid-Base Balance and Feedback Mechanisms
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Questions and Answers

What is the normal pH range for maintaining acid-base balance in the body?

  • 7.25-7.35
  • 7.50-7.60
  • 7.35-7.45 (correct)
  • 7.20-7.30

    • Which component is essential for the synthesis of thyroid hormones?

  • Calcium
  • Iron
  • Zinc
  • Iodine (correct)

    • What is a characteristic feature of negative feedback in hormonal balance?

  • Stimulus amplifies production
  • Stimulus reduces its own production (correct)
  • Stimulus creates a continuous cycle
  • Stimulus has no effect on production

    • Which hormone formation occurs when Monoiodotyrosine (MIT) and Diiodotyrosine (DIT) combine?

    <p>Triiodothyronine (T3)</p> Signup and view all the answers

    What buffer ratio is considered key for maintaining acid-base balance in the body?

    <p>20:1 bicarbonate to carbonic acid</p> Signup and view all the answers

    In primary hypothyroidism, what is a likely consequence of impaired T3 and T4 synthesis?

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

    Which of the following best describes how proteins function in acid-base balance?

    <p>Can function as either acidic or basic buffers</p> Signup and view all the answers

    What is a potential effect of elevated reverse T3 (rT3) levels?

    <p>Decrease in metabolic rate</p> Signup and view all the answers

    What primary mechanism does hemoglobin serve in relation to acid-base balance?

    <p>Transports CO2</p> Signup and view all the answers

    Which statement accurately describes the role of bicarbonate in acid-base balance?

    <p>Bicarbonate and carbonic acid maintain a 20:1 ratio essential for buffering.</p> Signup and view all the answers

    In conditions of respiratory acidosis, which physiological change is expected in pCO2 levels?

    <p>pCO2 levels exceed 45 mmHg.</p> Signup and view all the answers

    What is the primary function of carrier proteins for hormones in circulation?

    <p>To provide controlled availability and extend the hormonal half-life.</p> Signup and view all the answers

    How does negative feedback influence hormonal balance?

    <p>It reduces its own production in response to increasing levels of a hormone.</p> Signup and view all the answers

    What condition is characterized by the presence of anti-TPO antibodies?

    <p>Primary Hypothyroidism caused by autoimmune processes.</p> Signup and view all the answers

    Which mechanism describes the process of recycling iodine in the thyroid gland?

    <p>Enzymes deiodinate MIT and DIT to recover iodine.</p> Signup and view all the answers

    Elevated levels of which hormone are indicative of hyperthyroidism and its associated conditions?

    <p>Triiodothyronine (T3)</p> Signup and view all the answers

    Which symptom is primarily associated with severe hypothyroidism in adults?

    <p>Myxedema, characterized by severe swelling and cognitive changes.</p> Signup and view all the answers

    What result occurs when Diiodotyrosine (DIT) molecules combine?

    <p>Formation of Thyroxine (T4).</p> Signup and view all the answers

    What is the role of hemoglobin in relation to CO2 transport?

    <p>It binds to CO2 in tissues and releases it in the lungs.</p> Signup and view all the answers

    What is a significant difference between positive and negative feedback mechanisms in the body?

    <p>Positive feedback amplifies a stimulus until a certain endpoint is reached, whereas negative feedback maintains hormonal balance by reducing its production.</p> Signup and view all the answers

    Which of the following statements regarding the binding of thyroid hormones is accurate?

    <p>Both T3 and T4 have controlled availability in circulation due to binding to carrier proteins.</p> Signup and view all the answers

    Which factor is most likely to contribute to primary hypothyroidism aside from iodine deficiency?

    <p>Antibody-mediated destruction of the thyroid gland.</p> Signup and view all the answers

    What role does bicarbonate play in the body's acid-base balance?

    <p>It maintains a 20:1 ratio with carbonic acid to regulate pH.</p> Signup and view all the answers

    In the metabolic process involving thyroid hormones, what is typically the first step of T4 conversion?

    <p>T4 is primarily converted to T3 in the liver.</p> Signup and view all the answers

    Which statement correctly identifies a common symptom associated with hyperthyroidism?

    <p>Nervousness, weight loss, and increased heat sensitivity.</p> Signup and view all the answers

    How does reverse T3 (rT3) influence the thyroid hormone function during stress or illness?

    <p>It prevents the conversion of T4 to T3.</p> Signup and view all the answers

    What is a characteristic feature of hemoglobin's function in acid-base balance?

    <p>Hemoglobin releases more CO2 when pH levels decrease.</p> Signup and view all the answers

    What is the primary reason for elevated Thyroid-Stimulating Hormone (TSH) levels in primary hypothyroidism?

    <p>Reduced synthesis of T3 and T4 by the thyroid gland.</p> Signup and view all the answers

    Which statement about reverse T3 (rT3) in thyroid hormone metabolism is accurate?

    <p>rT3 serves as an inactive form of T4 that increases during stress or illness.</p> Signup and view all the answers

    In the context of acid-base balance, what is the role of phosphate as a buffer system?

    <p>It assists in the excretion of H+ ions.</p> Signup and view all the answers

    Which of the following statements accurately describes the storage and release of thyroid hormones?

    <p>Thyroid hormones utilize carrier proteins to enhance their half-life in circulation.</p> Signup and view all the answers

    In which scenario would you expect elevated levels of pCO2 to indicate respiratory acidosis?

    <p>Impaired respiratory function leading to reduced ventilation.</p> Signup and view all the answers

    Which of the following conditions is primarily associated with Hashimoto's Thyroiditis?

    <p>Elevated anti-TPO antibodies.</p> Signup and view all the answers

    What differentiates positive feedback from negative feedback in hormonal regulation?

    <p>Positive feedback increases hormone production until a certain goal is achieved.</p> Signup and view all the answers

    How does the bicarbonate buffer system operate in maintaining acid-base balance?

    <p>Bicarbonate plays a crucial role in neutralizing excess H+ ions in the blood.</p> Signup and view all the answers

    What impact does iodine deficiency have on thyroid hormone production?

    <p>It impairs the synthesis of T3 and T4, increasing TSH levels.</p> Signup and view all the answers

    What happens during the physiological responses to an increase in carbon dioxide (CO2) levels?

    <p>The kidneys increase HCO3- reabsorption and H+ excretion.</p> Signup and view all the answers

    Study Notes

    Acid-Base Balance

    • Maintenance: Lungs and kidneys maintain hydrogen ion (H+) levels.
    • Buffer Systems:
      • Bicarbonate: Key buffer, with a 20:1 ratio to carbonic acid.
      • Hemoglobin: Transports carbon dioxide (CO2).
      • Phosphate: Aids in hydrogen ion (H+) excretion.
      • Proteins: Can act as either acids or bases.
    • pH:
      • Normal Range: 7.35-7.45
      • Above 7.45: Alkalosis
    • pCO2:
      • Normal Range: 35-45 mmHg
      • Above 45 mmHg: Respiratory acidosis

    Acid-Base Imbalances

    Feedback Mechanisms

    • Negative Feedback:
      • Most common mechanism for hormonal balance.
      • Stimulus reduces its own production, maintaining stability.
    • Positive Feedback:
      • Less common.
      • Amplifies a stimulus until a specific endpoint is reached.

    Thyroid Gland Overview

    • Location: Neck, composed of follicles filled with colloid.
    • Key Components:
      • Colloid: Contains thyroglobulin (Tg), crucial for thyroid hormone production.
      • Iodine: Essential for thyroid hormone synthesis, actively transported into the gland.

    Thyroid Hormone Formation

    • Thyroglobulin (Tg): Primary protein in thyroid follicles.
    • Iodine Binding:
      • Tyrosine residues on Tg bind iodine to form:
        • Monoiodotyrosine (MIT)
        • Diiodotyrosine (DIT)
    • Hormone Formation:
      • MIT + DIT = Triiodothyronine (T3)
      • DIT + DIT = Thyroxine (T4)
    • Release: T3 and T4 are released into the bloodstream upon TSH stimulation.
    • Recycling: Enzymes deiodinate MIT and DIT to recover iodine.

    Thyroid Hormone Metabolism

    • T4 Conversion: Primarily converted to the active form (T3) in the liver.
    • Reverse T3 (rT3): Inactive form of T4; increases during stress, illness, or certain medications.
    • Binding: T3 and T4 bind to TBG, TBPA, and albumin for controlled release.

    Thyroid Disorders

    • Hypothyroidism:
      • Symptoms: Lethargy, fatigue, cold intolerance, myxedema (adults), cretinism (children).
      • Anti-TPO antibody: common
    • Primary Hypothyroidism:
      • Symptoms: Impaired T3/T4 synthesis, increased TSH levels.
      • Causes: Iodine deficiency, Hashimoto's Thyroiditis (autoimmune attack on thyroid tissue).
    • Hyperthyroidism (Thyrotoxicosis):
      • Symptoms: Low TSH level (opposite of primary hypothyroidism).

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    Description

    Test your knowledge on acid-base balance maintenance, buffer systems, and the various imbalances that can occur. Additionally, explore feedback mechanisms, both negative and positive, and their roles in hormonal regulation. This quiz will challenge your understanding of these essential physiological concepts.

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