Endocrine welcome session

Question 1

what are the three classes of hormone and what is each derived from ?

Answer 1

peptide/protein - composed of amino acid chains
amine - derived from tyrosine or tryptophan
steroid - derived from cholesterol

Question 2

what is the pathway of a peptide hormone ?

Answer 2

transcribed as a preprohormone in nucleus
cleaved to a pro hormone in the endoplasmic reticulum where it can be stored
transported through Golgi apparatus via vesicle where it is cleaved to active hormone
all products are exocytosed

Question 3

describe the mechanism of action of peptide hormones on the target cell

Answer 3

bind to membrane receptors as they are lypophobic

most activate GPCR or tyrosine kinase to phosphorylate existing intracellular proteins

Question 4

what are the two classes of amine hormones and what are examples of each ?

Answer 4

catecholamines - dopamine, epinephrine, norepinephrine - these follow the same mechanism as peptide hormones
thyroid hormones - thyroxine, triiodothyronine - follow same mechanism as steroid hormones

Question 5

describe the pathway of steroid hormones

Answer 5

synthesised as needed
diffuse directly out of cells
bound to carrier proteins as they are lypophilic

Question 6

what organs produce steroid hormones and what types do they produce?

Answer 6

gonads - sex steroids
placenta - HCG, sex steroids
kidney - vitamin D3
adrenal cortex - corticosteroids