ADRENAL GLANDS - Physiology Lecture SlideshowADRENAL GLANDS - Physiology Lecture Slideshow

Learning Objectives

At the end of the lecture all the students should be able


  • Explain the location of adrenal gland, its functional anatomy and importance.
  • Elucidate the mechanism of synthesis of the adrenal hormones.
  • Know the different hormones secreted from adrenal cortex and medulla.
  • Elucidate the general features regarding the ACTH

Adrenal Glands

  • Divided into two parts; each with separate functions
  • Adrenal Cortex
  • Adrenal Medulla

Zona Glomerulosa

  • Outermost zone – just below the adrenal capsule
  • Secretes mineralocorticoids.
  • Mineralocorticoids are termed as they are involved in regulation of electrolytes in ECF.
  • The naturally synthesized mineralocorticoid of most importance is aldosterone.
  • The other is deoxycorticosterone.


  • Aldosterone
  • Deoxycorticosterone
  • Corticosterone
  • 9α- Fluorocortisol
  • Cortisol
  • Cortisone

Zona Fasciculata

  • Middle zone – between the glomerulosa and reticularis
  • Primary secretion is glucocorticoids.
  • Glucocorticoids, as the term implies, are involved the increasing of blood glucose levels. However they have additional effects in protein and fat metabolism.
  • The naturally synthesized glucocorticoid of most importance is cortisol.

Zona Reticularis

  • Innermost zone – between the fasciculata and medulla
  • Primary secretion is androgens.
  • Androgenic hormones exhibit approximately the same effects as the male sex hormone – testosterone.

Overlap in the secretions of androgens and glucocorticoids exist between the fasciculata and reticularis.


  • Cortisol
  • Corticosterone
  • Cortisone
  • Prednisolone
  • Methylprednisolone
  • Dexamethasone

Synthetic pathway

  • LDL
  • Via endocytosis
  • ACTH
  • Cholesterol desmolase as rate limiting enzyme

ACTH: corticotropin

  • Cell: Corticotropes
  • Type: peptide 39 aa
  • Receptor: cell surface
  • Mechanism of Action: cAMP
  • CRF?


  • Transcortin
  • Cortisol binding globulin
  • Albumin
  • 90-95% cortisol
  • 60% aldosterone


  • In liver
  • Conjugated to glucuronic acid and sulphates
  • Excretion via feces and urine

Regulation of glucocorticoids

  • Circadian Rhthem
  • Highest level at 6 A.M.
  • About 75 % of cortisol are produced at 4-10 AM
  • These changes are parallel to changes in ACTH and CRH
  • Changes in sleep wake cycles as in shift worker results in daily changes in rhythm of cortisol secretion



  1. Dopamine
    – Biosynthetic precursor of noradrenaline and adrenaline
    – Acts as a neurotransmitter in the central nervous system
  2. Noradrenaline (norepinephrine)
    – Neurotransmitter of sympathetic nerves (Autonomic
    Nervous System)
  3. Adrenaline (epinephrine)
    – Produced primarily in the adrenal medulla
    – Only catecholamine whose action is strictly hormonal

Regulation of Adrenal Medullary Secretion

Catecholamine receptors

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