Fun Fact - Pituitary Is Not The Master Gland

The pituitary gland is often called the master gland as it controls the functions of various other endocrine glands like - Thyroid gland, Adrenal gland, Kidney etc. Well, at least we're taught to call the pituitary gland as the master gland from our school-days.


Another article in the fun fact series and once again, another lie is gonna get debunked. You can read the previous articles in the "Fun Fact" series by going to the following link -

• Fun Facts - Read To Get Surprised

The Pituitary gland

Source - A Fair Go

The pituitary gland is divided into two lobes - i) Anterior lobe, ii) Posterior lobe.

i) Anterior lobe - This lobe secretes many hormones. Some examples are -

• Adrenocorticotrophic hormone (ACTH).
• Luteinizing hormone (LH).
• Prolactin (PRL).
• Growth hormone (GH).

ii) Posterior lobe - This lobe secretes two hormones -

• Oxytocin.
• Vasopressin or Antidiuretic hormone (ADH).

But there are some misconceptions regarding the hormones secreted from the posterior lobe of the pituitary gland. More on that later.

Why pituitary is called the master gland?

Let's make you understood this segment by giving an example. Thyroid-stimulating hormone or TSH, secreted from the anterior lobe of the pituitary gland, acts on the Thyroid gland to stimulate the production of Tetraiodothyronine or Thyroxine (T₄) and Triiodothyronine (T₃). 

So, the pituitary secretes a hormone which controls the function of another gland. That's why it is called as the master gland. Like TSH, other hormones from pituitary gland such as ACTH and LH act on Adrenal Cortex and Interstitial cells of Leydig respectively.

Source - Health Is A Journey

Revelling time now

The pituitary gland is under the control of Hypothalamus. The anterior lobe of pituitary and hypothalamus are linked by a portal system called "Hypothalamo - Hypophyseal Portal System." There are neurones called Parvocellular neurones or Parvocellular neurosecretory cells in the Hypothalamus.

These neurones secrete releasing hormones and inhibiting hormones to control the secretion of the anterior pituitary. Some examples are given below -

• Corticotropin-releasing hormone (CRH).
• Thyrotropin-releasing hormone (TRH).
• Prolactin-inhibiting hormone (PIH).

The axons of Parvocellular neurones terminate on the capillary network of Hypothalamo - Hypophyseal Portal System in the median eminence of Hypothalamus. So the above hormones reach the anterior pituitary via the portal system. CRH and TRH control the secretion of ACTH and TSH from the anterior pituitary respectively.

Source - Bioninja

Magnocellular neurones of the hypothalamus secrete Oxytocin and Vasopressin. These hormones are then carried to the posterior pituitary. Only then the posterior pituitary can secrete ADH and Oxytocin into the blood.

Conclusion

You can read other articles in the fun facts series by going to the following links -

• Why the first cry of a baby is so important?
• Can your peni* get smaller?

As you can see, hormones from the hypothalamus control the secretions of hormones from the pituitary gland. Are you still gonna call the pituitary gland as the master gland?