The Posterior Lobe of Pituitary Gland MCQ - Practice Questions with Answers

• The posterior pituitary is actually an extension of the neurons of the hypothalamus.
• It comprises of 25% part of pituitary
• The cell bodies of these regions rest in the hypothalamus, but their axons descend as axon terminals in the posterior pituitary
• The axon terminals are embedded in a neuroglial tissue formed of cells known as pituicytes
• The posterior pituitary gland does not produce hormones, but rather stores and secretes hormones produced by the hypothalamus.
• These hormones are stored in small vesicles in the axons and terminals called Herring bodies.

Hormones released from Posterior Lobe:

1. Oxytocin:

• This hormone is produced by Paraventricular nuclei in the hypothalamus and is stored in posterior pituitary 
• This hormone stimulates the contraction of smooth muscles of the uterus in pregnant women and causes easy childbirth. 
• It also contracts the smooth muscles of mammary glands in lactating mothers and facilitates the flow of milk at the time of suckling
• Thus it is known as 'Birth hormone' or 'Milk Ejecting Hormone'
• Artificial Oxytocin is given to induce labour pain during parturition and this is known as Pitocin
• Oxytocin also stimulates the relaxation of the gallbladder, urinary bladder and intestine.

2. Vasopressin or Antidiuretic Hormone (ADH):

• This is produced by Supraoptic nuclei in the Hypothalamus and is stored in posterior pituitary
• The primary function of vasopressin is to increase reabsorption of water in the distal convoluted tubules and collecting tubules of the kidney. 
• So its deficiency in body increases the volume of urine causing diabetes insipidus. 
• This type of diabetes is different from diabetes mellitus as in this the urine is free from sugar.
• Another important function of ADH is to bring about contraction of smooth muscles of the intestine, gallbladder, urinary bladder and blood vessels. 
• Hence, large quantities of the hormone cause the arterial blood pressure to rise due to the contraction of peripheral, arterioles. 
• Intake of alcohol reduces ADH secretion.