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Related Concept Videos

Functions of Thyroid Hormones01:18

Functions of Thyroid Hormones

The thyroid hormone (TH) plays a pivotal role in the intricate orchestration of physiological processes, exerting profound effects on development, metabolism, and homeostasis throughout different life stages.
TH is indispensable for the normal development and maturation of the skeletal, muscular, and nervous systems during fetal and childhood growth. It facilitates bone mineral turnover and regulates protein synthesis in developing tissues, contributing significantly to overall growth and...
Exercise and Cardiovascular Response01:20

Exercise and Cardiovascular Response

Exercise significantly impacts cardiovascular response, which is crucial for understanding patient health and designing effective treatment plans.
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
Hyperthyroidism II: Pathophysiology01:27

Hyperthyroidism II: Pathophysiology

Hyperthyroidism is a hypermetabolic state caused by elevated levels of thyroid hormones, triiodothyronine (T3) and thyroxine (T4). It results from dysregulation at the thyroid, pituitary, or immune system level and affects multiple organ systems.PathophysiologyThe most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder in which antibodies, specifically thyroid-stimulating antibodies (TSAb), a subtype of TSH receptor antibodies (TRAb), bind to and activate TSH receptors...
Synthesis and Regulation of Thyroid Hormones01:20

Synthesis and Regulation of Thyroid Hormones

Low blood levels of the thyroid hormones — triiodothyronine (T3) and thyroxine (T4) — signal the hypothalamus to release the thyrotropin-releasing hormone (TRH). TRH then reaches the pituitary gland and stimulates the release of thyroid-stimulating hormone(TSH) into the bloodstream.
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...
Hyperthyroidism I: Introduction01:25

Hyperthyroidism I: Introduction

Hyperthyroidism is a type of thyrotoxicosis characterized by the thyroid gland's overproduction of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). This hormone excess increases the basal metabolic rate and enhances sensitivity to catecholamines.DiagnosisDiagnosis is based on clinical features and biochemical testing. It typically shows suppressed thyroid-stimulating hormone (TSH) levels below 0.4 mIU/L, with elevated free T3 and/or T4. Additional tests, including thyroid...
Hypothyroidism II: Pathophysiology01:23

Hypothyroidism II: Pathophysiology

Hypothyroidism is a disorder characterized by insufficient production of thyroid hormones, which regulate metabolism, energy balance, and multiple organ systems.TypesHypothyroidism is classified based on the level of dysfunction. Primary hypothyroidism results from intrinsic thyroid gland dysfunction, causing reduced hormone production despite normal or increased stimulation. Secondary hypothyroidism arises from inadequate thyroid-stimulating hormone (TSH) secretion by the pituitary. Tertiary...

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Related Experiment Video

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Impact of High-intensity Interval Exercise and Moderate-Intensity Continuous Exercise on the Cardiac Troponin T Level at an Early Stage of Training
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Thyroid hormone responses to endurance exercise.

E A Graves1, H C Schott, J V Marteniuk

  • 1Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824-1314, USA.

Equine Veterinary Journal. Supplement
|April 4, 2007
PubMed
Summary

Prolonged endurance exercise in horses causes temporary reductions in circulating thyroid hormones, including thyroxine (T4) and triiodothyronine (T3). These changes are most significant after longer distances and during recovery periods.

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Area of Science:

  • Equine physiology
  • Endocrinology
  • Exercise science

Background:

  • Limited data exists on thyroid hormone changes in horses during prolonged endurance exercise.
  • Understanding these fluctuations is crucial for assessing thyroid function in athletic horses.

Purpose of the Study:

  • To investigate the impact of varying distances of endurance exercise on serum iodothyronine concentrations in horses.
  • To analyze the time course of thyroid hormone changes during and after prolonged exercise.

Main Methods:

  • Serum iodothyronine concentrations (T4, T3, FT4, FT3, rT3) were measured in horses before and after endurance rides of 40, 56, 80, and 160 km.
  • Measurements were also taken daily during a 5-day, 424 km ride and for 72 hours post-exercise following a simulated 60 km treadmill test.

Main Results:

  • Shorter rides (40-56 km) had minimal impact, except for a slight decrease in free thyroxine (FT4).
  • Longer rides (80-160 km) and multi-day exercise led to significant decreases in total thyroxine (T4), total triiodothyronine (T3), FT4, and free triiodothyronine (FT3).
  • Post-exercise recovery showed the greatest decrease at 12 hours, with concentrations returning to baseline by 24 hours.

Conclusions:

  • Endurance exercise induces transient decreases in serum iodothyronine concentrations in horses.
  • These findings are essential for interpreting thyroid gland function tests in endurance horses, considering exercise-induced hormonal shifts.