Question

Describe two (2) mechanisms of hormonal action. Give the general hormone type that utilizes each mechanism

Answer 1

There are two mechanism for hormonal action.

• Extracellular action mechanism
• Intracellular action mechanism

Extracellular action mechanism is followed by the several type of hormones which bind the receptor present on the membrane and form the hormone receptor complex In this mechanism several steps are involved

(i) Hormon-Receptor complex formation :Hormone bind to specific receptor molecules present on the membrane and form Hormone-Receptor Complex.

(ii)Release of secondary messengers :A secondary messenger is released by the transducer molecule(G-Protein) .Secondary messengers are mostly cAMP .Secondary messenger act on the intracellular receptor for specific action and expressing hormonal action.

Extracellular mechanism is follwed by amino acid derivatives, peptides or polypeptide protein hormones such as Insulin,growth hormone,epinephrine and norepinephrine,FSH,oxytocin,Vasopressin ,Glucagon,Calcitonin, Endosphins etc,

Intracellular action mechanism is followed by hormones which can cross the lipid bilayer membrane of cell.These hormones directly act on the intracellular receptor and form hormone receptor complex inside the cell or inside nuclus(according to location of receptor inside cell).Upon formation of hormone-receptor complex , it act directly on the genomic site and affect the gene expression by promoting or inhibiting the formation of specific mRNA and proteins.

Intracellular mechanism is follwed by steroid hormones such as aldosterone, cortisol,Androgen,estrogen,testesterone etc.