Adrenal Medulla MCQ - Practice Questions with Answers

• The adrenal medulla develops from the neuroectoderm.
• The adrenal medulla consists of granular cells that are modified postganglionic cells of the sympathetic nervous system which have lost normal processes and have acquired a glandular function.
• These cells are connected with the pregan­glionic motor fibres of the sympathetic nervous system.
• The medulla of the adrenal glands secretes two hormones: 
  • norepinephrine (norad­renaline)  
  • epinephrine (adrenaline)
• These hormones are synthesized from amino acid tyrosine.

Norepinephrine or Noradrenaline:

• It regulates the blood pressure under normal condition. 
• It causes constriction of essentially all the blood vessels of the body. 
• It causes increased activity of the heart, inhibition of gastrointestinal tract, dilation of the pupils of the eyes and so forth.

Epinephrine or Adrenaline:

• It is secreted at the time of emergency. Hence it is also called emergency hormone.
• It has a greater effect on cardiac activity than norepinephrine.
• It causes only weak con­striction of the blood vessels of the muscles in comparison with a much stronger constriction that results from norepinephrine.
• Both adrenaline and noradrenaline act on the cells of skeletal, cardiac and smooth muscles and blood vessels and fat cells. 
• Because of the role of their hormones, the adrenal glands are also called ‘glands of emergency’.

Note: Stimulation of Sympathetic nerves to adrenl medulla causes large quantities of epinephrine (adrenaline) and norepinephrine (noradrenaline) to be released into the blood circulation and then these hormones are carried to all the tissues of the body