Question

According to one of the theories of ageing, the decline and disappearance of which gland by late middle age is the primary cause of ageing?
A. Thyroid
B. Parathyroid
C. Thymus
D. The posterior lobe of the pituitary.

Answer 1

Hint: The continuous slow process by which an organism reaches to its older stages of life is called ageing. It is mainly found in many animals, including humans and fungi. In the case of humans, ageing includes a collection of changes (physiological, physical and social changes) that has come over time.

Complete answer: The thyroid gland is located in the neck. The shape of the thyroid gland resembles the butterfly. Thyroid gland comprises two lobes. The thyroid gland is responsible for producing two hormones. These are triiodothyronine and thyroxine. Thyroid hormone helps to regulate the metabolism of the body.
Parathyroid gland: The parathyroid gland is found in the neck just behind the thyroid gland. In the case of humans, there are four parathyroid glands present. When the calcium level in the blood decreases, the secretion of parathyroid hormones is started. Thus parathyroid hormones are responsible for regulating the calcium level in the body.
Thymus: Thymus is found at the front position of the heart, within the anterior superior mediastinum. The thymus comprises two lobes. Each lobe is composed of an outer cortex and central medulla that are enclosed by a capsule. During puberty, the growth of thymus glands remains very high. It's growth gradually decreases with age. And in the old ages (70), the Thymus gland becomes very short. The thymus gland is involved in the production of T lymphocytes. T lymphocytes are the major cells of our immune system. So, the decline or disappearance of the thymus gland in the old ages is known as the primary reason for ageing.
The posterior lobe of the pituitary: pituitary gland is situated at the base region of our brain. The pituitary gland is considered as the master gland. The posterior lobe of the pituitary is also known as the neurohypophysis. It is responsible for producing the hormones, named oxytocin and vasopressin.
So, the correct answer is “Option C”.

Note: Still now, the causes of ageing are not exactly known. It is believed that the collection of damages like oxidation of DNA may lead to failure of a biological system. The characteristics of ageing can be visible physically like skin drying, loose of skin, spots on skin etc. Apart from physical psychological and social changes are also noticed with the growing age.