Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal? a. Greater production of T 3 than of T 4 b. Hyposecretion of TSH c. Hypersecretion of MSH d. A decrease in the thyroid secretion of calcitonin

Welcome back. Here's our next problem. An individual who had a severe iodine deficiency developed hypothyroidism. The five rock scene T. four level in their blood sample will be blank. And we have choices of high, low normal or normal to high. Well hypothyroidism um means alot level too low a thyroid hormone. And if we can't remember hypo or hyper we're gonna look here. We see this individual has severe iodine deficiency. Well thyroid hormone is in form of either T. Four or T three. T four being the most prevalent form throughout the body. And both of these are partly composed of iodine. So if we have an iodine deficiency we don't have enough iodine and that would necessarily result in low levels Of that T. four T. 3 because we don't have enough iodine for its composition. So when we look at our choices, we know that our answer would have to be choice be low. Because the deficiency of iodine would mean we don't have enough to make T. Four and T. Three. Hypothyroidism is low levels of thyroid hormone as we'd expect from that iodine deficiency, if we have trouble remembering hypo versus hyper, think of a hyper child having high energy. So in this case hypothyroidism, a low level of the thyroid hormone. So choice B is our answer. Low. See you in the next video

Ch. 45 - Hormones and the Endocrine System

Campbell - Campbell Biology 11th Edition

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Urry 11th Edition

Ch. 45 - Hormones and the Endocrine System

Problem 6

Chapter 45, Problem 6

Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal?
a. Greater production of T₃ than of T₄
b. Hyposecretion of TSH
c. Hypersecretion of MSH
d. A decrease in the thyroid secretion of calcitonin

Verified step by step guidance

Understand that hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormones, primarily T3 (triiodothyronine) and T4 (thyroxine).

Recognize that iodine is essential for the production of T3 and T4. Since the iodine level is normal, the issue is not due to iodine deficiency.

Consider the role of TSH (Thyroid Stimulating Hormone), which is produced by the pituitary gland and stimulates the thyroid to produce T3 and T4. Hyposecretion of TSH would lead to reduced stimulation of the thyroid gland, resulting in lower production of thyroid hormones.

Evaluate the other options: Greater production of T3 than T4 is not typically associated with hypothyroidism, hypersecretion of MSH (Melanocyte Stimulating Hormone) is unrelated to thyroid function, and calcitonin is involved in calcium regulation, not directly in thyroid hormone production.

Conclude that the most likely explanation for hypothyroidism in this scenario, given normal iodine levels, is hyposecretion of TSH, as it directly affects the thyroid's ability to produce sufficient hormones.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Hypothyroidism

Hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormones, leading to symptoms like fatigue, weight gain, and depression. It can be caused by various factors, including autoimmune diseases, certain medications, or issues with the pituitary gland. Understanding the underlying cause is crucial for effective treatment.

Thyroid-Stimulating Hormone (TSH)

TSH is a hormone produced by the pituitary gland that stimulates the thyroid gland to produce thyroid hormones, T3 and T4. In cases of hypothyroidism, TSH levels are typically elevated as the body attempts to stimulate more hormone production. However, if TSH is low or normal, it may indicate a problem with the pituitary gland itself, leading to hyposecretion of TSH.

Iodine and Thyroid Function

Iodine is an essential element for the production of thyroid hormones. A deficiency in iodine can lead to hypothyroidism, but if iodine levels are normal, other causes must be considered. This includes issues with hormone production or regulation, such as pituitary gland dysfunction, which affects TSH secretion and subsequently thyroid hormone levels.

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Growth factors are local regulators that

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d. Bind to cell-surface receptors and stimulate growth and development of target cells.

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Which hormone is incorrectly paired with its action?

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d. Melatonin — affects biological rhythms and seasonal reproduction

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What do steroid and peptide hormones typically have in common?

a. Their solubility in cell membranes

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c. The location of their receptors

d. Their reliance on signal transduction in the cell

The relationship between the insect hormones ecdysteroid and PTTH is an example of

a. An interaction of the endocrine and nervous systems.

b. Homeostasis achieved by positive feedback.

c. Homeostasis maintained by antagonistic hormones.

d. Competitive inhibition of a hormone receptor.

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Textbook Question

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Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal? a. Greater production of T3 than of T4 b. Hyposecretion of TSH c. Hypersecretion of MSH d. A decrease in the thyroid secretion of calcitonin

Verified video answer for a similar problem:

Key Concepts

Hypothyroidism

Thyroid-Stimulating Hormone (TSH)

Iodine and Thyroid Function

Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal?
a. Greater production of T₃ than of T₄
b. Hyposecretion of TSH
c. Hypersecretion of MSH
d. A decrease in the thyroid secretion of calcitonin