[Biology Class Notes] on Thyroid Gland Pdf for Exam

Topics covered in the Chapter – Thyroid Gland

Some of the topics which have been covered in the Thyroid Gland – Structure, Location, Function and Disorder PDF are as  follows:

Thus, downloading the Thyroid Gland – Structure, Location, Function and Disorder PDF will be very advantageous to students for their exam preparation.

The thyroid gland is an endocrine gland. The thyroid gland’s location is in the front or anterior part of the neck, below Adam’s apple. The thyroid gland consists of two connected lobes and two-thirds of the lower lobe are joined with a thin strand of tissue which is named thyroid isthmus. Thyroid gland’s anatomy or structure comprises a functional unit which is called thyroid follicle, lined with follicular cells and parafollicular cells occasionally that bound a lumen which contains colloid. The thyroid gland’s function is the secretion of hormones. The thyroid gland secretes primarily two hormones which are Triiodothyronine (T3) hormone and the Thyroxine hormone (T4).

Thyroid Gland Structure

The thyroid gland anatomy comprises a butterfly-shaped organ which has two lobes that are connected with the help of a narrow isthmus. The gland weighs 25g in adults, and the lobe is 5cm long and has a thickness of 2cm. The gland is smaller in men as compared to women. The gland lies in front of the trachea and larynx in the anterior of the neck.  The thyroid gland diagram is given below.

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Thyroid Gland Location

The specific thyroid gland location is that it is located in the front part of the neck in the middle of C5 and T1 vertebrae. The thyroid gland’s anatomy has two lobes which are embedded in the posterior surfaces of the parathyroid gland. This is the thyroid gland location.

Thyroid Gland Function

Primarily thyroid gland’s function is the secretion of hormones that affect all the body tissues. Hence in anatomy thyroid gland plays a crucial role. The hormones secreted by the thyroid gland include the Triiodothyronine (T3) hormone and the Thyroxine hormone (T4). These thyroid gland hormones perform different essential tasks in the body. Thyroxine is released into the bloodstream by the thyroid gland and travels to organs like the kidney and liver where they are transformed into its active state triiodothyronine. The T3 hormone, on the other hand, affects physiological processes such as development, metabolism, growth, etc.

Thyroid Gland Disorder

The symptoms of a thyroid gland disorder may not always be visible. This is mainly because of many other factors which cause similar types of symptoms. The treatment is generally done in accordance with the symptoms. For example, being excessively tired can be associated with other disorders such as narcolepsy, but the underlying cause may be a thyroid disorder. The main symptoms of a thyroid disorder are weight gain, high cholesterol, lack of concentration, nervousness and change in menstrual cycle in women. The thyroid gland may become vulnerable to various forms of disorders owing to problems such as malignant lumps, excess hormone secretion and unusual gland growth, etc. Stress may also become a cause or an aggravator of a thyroid gland disorder. Some common thyroid disorders are:

1. Goitre

The thyroid gland gets excessively enlarged, causing the oesophagus to get obstructed along with other organs in the neck and chest region. This creates problems in eating and breathing. An Iodine deficiency generally causes it.

2. Thyroid Cancer

Although a prevalent form of cancer, this has comparatively higher chances of survival than other types of cancer. Papillary thyroid cancer, medullary cancer, follicular cancer and anaplastic cancer are the four types of thyroid cancer.

 

3. Hyperthyroidism and Hypothyroidism

The two disorders are caused by thyroid gland hormones. Hyperthyroidism is caused when thyroid glands secrete an excess of thyroxine. The symptoms change in appetite, insomnia, fatigue, weight loss, and increased urination. Hypothyroidism is caused by under secretion of the thyroid hormones. This disorder is primarily triggered by an autoimmune disorder named Hashimoto disease. In this disease, the thyroid gland is attacked by the antibodies lowering the production of hormones.

Treatment for Thyroid

The most common treatment in disorders such as hyperthyroidism involves the replacement of thyroxine with another synthetic hormone called levothyroxine (or L-thyroxine) which is injected or taken orally. Cancer is treated successfully with radiation.

Solved Examples: 

1. What is the function of the thyroid gland?

The thyroid gland secretes hormones which influence the functioning of tissues in the body. The gland secretes the T3 and T4 hormones and influences processes like growth and metabolism in the body.

Did You Know?

Iodine deficiency which is one of the leading causes of goitre occurs mostly in mountainous regions. If this disease becomes widespread among a population, then it is referred to as an endemic goitre. Iodine deficient pregnant women may give birth to infants who have thyroid hormone deficiency from birth. To deal with this condition, often iodised salt is used to incorporate iodine in the diet. This has helped in the eradication of cretinism in most of the developed countries, and more than 120 countries have made salt iodination compulsory.

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