Question Video: Identifying the Thyroid Gland in the Human Body | Nagwa Question Video: Identifying the Thyroid Gland in the Human Body | Nagwa

Question Video: Identifying the Thyroid Gland in the Human Body Biology • Third Year of Secondary School

Which label on this diagram of the human body indicates the thyroid gland?

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Video Transcript

Which label on this diagram of the human body indicates the thyroid gland?

This question asks us to identify the thyroid gland in our diagram. To answer this, let’s review some key facts about the organ system represented by this diagram. This diagram shows the endocrine system. The endocrine system is composed of many different organs with functions that may seem unrelated at first. For instance, some of these organs influence reproduction, while others aid in digestion. Some are even responsible for systemic effects like the regulation of metabolism, growth, and blood pressure. So, what do these organs have in common?

Glands of the endocrine system release hormones usually into the bloodstream. These hormones are chemical messengers that are carried around the body to their target cells to bring about a response. The pituitary gland, shown at the top of the diagram, just below the brain, is considered the master gland of the endocrine system. This is because it releases seven different hormones that influence other organs of the endocrine system, including the thyroid gland, adrenal glands, ovaries, and testes. For instance, the pituitary gland releases follicle-stimulating hormone, or FSH. This hormone is not only essential for development during puberty but also for control of the menstrual cycle and sperm production.

Another hormone released from the pituitary gland is thyroid-stimulating hormone, or TSH. So what organ does thyroid-stimulating hormone influence? You may have guessed the thyroid gland, as the clue was in the name. The thyroid gland is a butterfly-shaped endocrine gland, located at the base of your neck. It is made up of two types of secretory cells, follicular cells and parafollicular cells, as shown here. The follicular cells secrete the thyroid hormones thyroxine and triiodothyronine, which regulate the basal metabolic rate of the body. They are also involved in the control of heart rate, digestion, muscle control, and brain function.

The parafollicular cells secrete calcitonin. This hormone works with parathyroid hormone, which is secreted by the parathyroid glands to regulate blood calcium levels. When calcium levels rise above normal, calcitonin is released by the thyroid gland to bring the levels back down. When calcium levels in the blood drop below normal, parathyroid hormone is released to bring them back up.

It is the thyroid gland we have been asked to locate in this question, so let’s take another look at our diagram and review the structures marked by X, Y, and Z. Label X points to a structure in the brain that sits right above the pituitary gland, and this is the hypothalamus. While the pituitary gland is considered the master gland in the endocrine system, its secretions are actually regulated by the hypothalamus. Because the hypothalamus is part of the brain and the pituitary gland controls much of the endocrine system, the hypothalamus links the nervous and endocrine systems together.

Now let’s have a look at label Y. This is pointing to a gland that actually serves both the endocrine and digestive system. This organ is called the pancreas. And it is responsible for secreting the hormones insulin and glucagon from an area called the islets of Langerhans. These hormones are very important for regulating blood glucose levels. As well as secretion of hormones, it secretes digestive enzymes from the acinar cells and releases them down ducts into the duodenum.

This leaves us with letter Z. You can see it is a butterfly shape and found in the neck, which means we have already mentioned this gland, the thyroid gland. We can now answer this question correctly. We are asked which label on this diagram of the human body indicates the thyroid gland. And the correct label is Z.

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