Question

The posterior pituitary gland is not a true endocrine gland because
A. It secretes enzymes.
B. It is provided with a duct.
C. It only stores and releases hormones produced by the hypothalamus.
D. It is under regulation of hypothalamus

Answer 1

Hint: The pituitary gland is a small pea-sized gland that plays a major role in regulating vital body functions and general well-being. It is referred to as the body's master gland because it controls the activity of most other hormone-secreting glands.

Complete Answer:
The pituitary gland, also known as the hypophysis, is a ductless gland of the endocrine system that secretes hormones straightforwardly into the bloodstream. The term hypophysis, another name for the pituitary, refers to the gland’s location on the underside of the brain. The pituitary gland lies in the middle of the base of the skull and is housed within a bony arrangement called the sella turcica, which is situated behind the nose and immediately underneath the hypothalamus.

In most of the species, the pituitary gland is divided into three lobes: the anterior lobe, the intermediate lobe, and the posterior lobe. In humans, the intermediate lobe does not subsist as a distinct anatomic structure but slightly remains only as cells detached within the anterior lobe. Even so, the anterior and posterior lobes of the pituitary are functionally, anatomically, and embryologically different. While the anterior pituitary contains profuse hormone-secreting epithelial cells, the posterior pituitary is composed of unmyelinated secretory neurons.

The cells of the anterior pituitary embryologically result from an outpouching of the top of the pharynx and are known as Rathke’s pouch. Even though the cells emerge to be relatively homogeneous under a light microscope. The thyrotrophin produce and secrete thyrotropin (thyroid-stimulating hormone, TSH), the gonadotrophs both luteinizing hormone (LH) and follicle-stimulating hormone (FSH), the corticotrophs, adrenocorticotropic hormone (ACTH,-corticotropin), the somatotrophs, growth hormone (GH- somatotropin) and the prolactin.

The next lobe, the posterior lobe of the pituitary gland consists of extensions of processes that are axons from two pairs of a large cluster of nerve cell bodies in the hypothalamus. One of those nuclei is known as the supraoptic nuclei that takes the position immediately above the optic tract where the other nuclei paraventricular nuclei lie on each side of the third ventricle of the brain.

Oxytocin and vasopressin are produced by the hypothalamus but stored and are released into the bloodstream through the posterior pituitary. That is the reason why it is not a true endocrine gland. Endocrine glands are the ductless glands that produce and release hormones in the blood directly.

Therefore the correct answer is option C.

Note: The pituitary gland is known as the master gland because its hormones regulate other important endocrine glands including the adrenal, thyroid, and reproductive glands. And in some cases have straight regulatory effects in major tissues such as those of the musculoskeletal system.