Author: Carlos

A hormone is a chemical messenger. Here is what a hormone is, the three classes (peptide, steroid, amine), and why solubility predicts how each one acts.

How fat-soluble hormones act directly on genes through nuclear hormone receptors — the third receptor superfamily, its shared domain plan, and type I vs type II.

How cells carry a hormone signal inward using second messengers — cAMP, IP3 and DAG, calcium and cGMP — and how those cascades amplify and then switch off.

How cells turn large precursor proteins into finished peptide hormones — the convertases, the secretory pathway, and worked examples like insulin and C-peptide.

The pituitary gland is really two organs in one, and the hub of nearly every hormone axis. Its two lobes, its six anterior and two posterior hormones, and why so many peptide drugs target it.

The HPT axis is the three-tier chain — hypothalamus TRH, pituitary TSH, thyroid T4/T3 — that sets your metabolic pace. How it works, why the signals are peptides but the end hormone is not, and what a TSH test really reads.

Insulin is the 51-amino-acid peptide hormone that controls blood sugar — and the first protein ever sequenced and first recombinant drug. What it is, how it works, and how it was re-engineered.

Peptide pharmacokinetics explained through ADME: why peptides are injected, distribute in water, are cut by peptidases (not CYP450), clear renally, and how half-life extension works.

The hypothalamic-pituitary-adrenal (HPA) axis explained: CRH, ACTH from POMC, cortisol, its daily rhythm, feedback, and the MC2R melanocortin connection.

The hypothalamic-pituitary-gonadal (HPG) axis explained: GnRH pulses, LH and FSH, feedback, kisspeptin, and the drugs and research peptides that act on it.