Describe the production and secretion of thyroid hormones
What will be an ideal response?
All steps occur on thyroglobulin molecules within colloid; tyrosine-containing thyroglobulin is exported from follicular cells into colloid by exocytosis; thyroid captures iodine from blood and transfers it into colloid by iodine pump; within colloid, iodine attaches to tyrosine forming MIT and DIT; coupling process occurs between iodinated tyrosine molecules to form thyroid hormones as two DIT come together to form T4 and an MIT and DIT come together to form T3
Thyroid hormone is regulated by negative-feedback system between hypothalamic TRH, anterior pituitary TSH, and thyroid gland T3 and T4 . This feedback loop maintains thyroid hormones at relatively constant levels. TRH induces the anterior pituitary to release TSH, which in turn stimulates thyroid gland to release thyroid hormones. Thyroid hormones exert negative feedback to the anterior pituitary, decreasing TSH secretion. As thyroid levels fall, the negative feedback is removed, TSH is released again, and the cycle repeats.
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Which of these processes can occur without the direct use of ATP?A) Simple diffusionB) Facilitated diffusionC) Primary active transportD) Secondary active transportE) None of these can occur without the direct use of ATP
What will be an ideal response?
The bulk movement of air into and out of the lungs is called ________.
A. evacuation B. perspiration C. respiration D. ventilation
Explain the differences among the terms paracrine, autocrine, hormone, and cytokine.
What will be an ideal response?
Which of the following statements regarding renal handling of Na+ is correct?
A. In the absence of aldosterone, Na+ will be secreted by the cortical collecting ducts. B. In the proximal tubule, Na+ is actively transported across the luminal membrane of the tubular epithelial cells. C. Atrial natriuretic factor increases Na+ reabsorption. D. Na+ is actively reabsorbed in the ascending limb of the loop of Henle. E. Without vasopressin, the collecting duct is impermeable to Na+.