Endocrinology - Thyroid Function and Pathophysiology Flashcards
Where is the thyroid gland located?
In the anterior neck, spanning from the fifth cervical vertebra (C5) to the first thoracic vertebra (T1).
What is the shape of the thyroid gland?
Butterfly-shaped, consisting of two lateral lobes connected by an isthmus.
What are the basic structural units of the thyroid gland?
Follicles, which are spherical structures lined by a single layer of cuboidal epithelial cells surrounding a colloid-filled lumen.
What is the function of parafollicular cells in the thyroid?
They produce the hormone calcitonin, which helps regulate calcium levels in the blood.
Which hormones are produced by the thyroid gland?
Thyroxine (T4) and triiodothyronine (T3).
What role does iodine play in thyroid hormone production?
Iodine is essential for the synthesis of T3 and T4; it is actively transported into follicular cells and incorporated into thyroglobulin.
How is thyroid hormone release stimulated?
Thyroid-stimulating hormone (TSH) from the anterior pituitary gland stimulates the thyroid to release T3 and T4.
What regulates TSH secretion?
Thyrotropin-releasing hormone (TRH) from the hypothalamus and negative feedback from circulating T3 and T4 levels.
What are the primary functions of T3 and T4?
They increase metabolic activities, promote cell growth and division, and play a key role in embryonic development.
Which thyroid hormone is more active?
Triiodothyronine (T3) is more active than thyroxine (T4).
What is hyperthyroidism?
A condition characterized by excessive production of thyroid hormones, leading to increased metabolic activities.
What is Graves’ disease?
An autoimmune disorder and the most common cause of hyperthyroidism, where autoantibodies stimulate the thyroid to produce excess hormones.
What are common symptoms of hyperthyroidism?
Hyperventilation, tachycardia, muscle wasting, heat intolerance, insomnia, diarrhea, and weight loss.
How is Graves’ disease diagnosed?
Elevated levels of T3 and T4, suppressed TSH levels, and the presence of thyroid-stimulating immunoglobulins (TSI).
What are the treatment options for Graves’ disease?
Anti-thyroid medications (e.g., propylthiouracil, methimazole), radioactive iodine therapy, beta-blockers for symptom relief, and sometimes thyroidectomy.
What is hypothyroidism?
A condition characterized by low levels of thyroid hormones, leading to decreased metabolic activities.
What are common symptoms of hypothyroidism?
Lethargy, dry coarse skin, slow speech, mental sluggishness, cold intolerance, hoarse voice, constipation, weight gain, and edema.
