Select 93 more words to run Humanizer.
Select 93 more words to run Humanizer.
The thyroid gland is an important topic in physiology because it plays a crucial role in regulating many physiological processes in the human body. The thyroid gland produces hormones that regulate metabolism and affect many systems in the body, including the cardiovascular system, the nervous system, and the digestive system. Additionally, thyroid dysfunction can result in various conditions such as hypothyroidism and hyperthyroidism, which can have significant impacts on a patient's health.
Furthermore, an understanding of thyroid physiology is essential for medical professionals as the thyroid gland is a common site of disease and is frequently involved in endocrine disorders. Knowledge of thyroid physiology and related disorders is therefore critical for the diagnosis, treatment, and management of patients.
Read this blog further to get a quick overview of this important topic for NEET PG exam preparations.
Overview
The thyroid gland is located in the neck and it secretes the Thyroid hormones. The central theme of Thyroid hormones is Basal Metabolic Rate as thyroid regulates the BMR.
Thyroid hormone is the only hormone synthesized in the extracellular site. Thyroid is not essential to life, but Parathyroid hormone is essential to life. There are two types of Thyroid hormones :- T3 & T4.
Metabolic & Non-Metabolic Actions of Thyroid Hormones
T.H. performs metabolic & non-metabolic actions that are discussed below :-
Metabolic Actions
- Thyroid controls the BMR, so, the thyroid hormone increases the metabolic rate of all the cells in the body. If the metabolic rate increases then the oxygen consumption will increase and heat production will also increase. BEA increase in Na+ - K+ ATPase (pump) activity is associated with increase in B.M.R.
- Thyroid hormones are known to cause lipolysis as it increases all aspects of carbohydrates, protein and fats. Thyroid hormones are known to cause relative vitamin deficiency because vitamins are cofactors for metabolism.
Also Read : Resting Membrane Potential - Physiology
Non-Metabolic /Systemic Actions
- As B.M.R increases under the influence of thyroid hormone, all aspects of the cardiovascular system (CVS) will get stimulated resulting in increased heart rate, increased blood pressure, and increased cardiac output. There is a potentiating effect of the thyroid hormone on catecholamines. Because of this effect, thyrotoxicosis affected individuals have tremors as catecholamines have β receptors that increase and produce muscle tremors.
- Thyroid hormones are required for myelination in the nervous system in the first 6 years of life. Therefore, deficiency of these in 6 years of life results in improper myelination which causes Cretinism. The hallmark of cretinism is mental retardation.
- Thyroid also increases synaptic excitability. Therefore, hyperthyroid individuals suffer from insomnia & hypothyroid individuals suffer from Somnolence (excessive sleeping). Thyroid hormones also cause increased motility in the GIT tract.
DISORDERS OF THE THYROID HORMONES
Following are the disorders of thyroid hormones.
- Hypothyroidism
- It results in Cretinism in children leading to delayed milestones or mental retardation In adults, it results in Myxoedema as a result of GAG accumulation. Sub-dermal region & interstitium will absorb water on them making it jelly like consistent fluid causing Non-pitting type of Edema. It is seen on the shin (over tibia) called Pretibial Edema.
- In addition to the above feature of Myxoedema, the hypothyroid individuals have a yellowish tint to their skin, because thyroid hormone is required to convert carotene into Vitamin A. which is not possible in case of hypothyroidism. Therefore, carotene will accumulate on the skin which will give it a yellow tinge. Additional features of Myxoedema may also include obesity, intolerance to cold, etc.
- HYPERTHYROIDISM
- Hyperthyroidism means excess secretion of thyroid hormones. When hyperthyroidism is accompanied by toxic symptoms, it is called thyrotoxicosis or Grave’s disease. The toxic symptoms or features mentioned include tremors, sleeping, heart rate > 90 beats/min. Grave’s disease is auto-immune in nature.
- Thyroid gland is stimulated by thyroid stimulating immunoglobulin (TSI) in the long run which results in hyperthyroidism. The hyperthyroid individual will show symptoms like a thin body, intolerance to heat, increased Heart rate and some special features like protrusion of the eyeball, called exophthalmos.
Also Read: Symptoms of Hyperthyroidism
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