Hormone Types

Peptide Hormones

Hormones that are chains of amino acids, water-soluble, and bind to receptors on the cell surface.

Solubility of Peptide Hormones

Water-soluble, cannot pass through the cell membrane because water and fat don't mix.

Mechanism of Action for Peptide Hormones

Bind to receptors on the cell surface, activating second messenger systems like G-protein coupled receptors and cAMP.

Examples of Peptide Hormones

Insulin, Growth hormone, Parathyroid hormone, Epinephrine, Vasopressin.

Amine Hormones

Hormones derived from single amino acids, usually tyrosine or tryptophan.

Types of Amine Hormones

Water-soluble amines (like adrenaline) and fat-soluble amines (like thyroid hormones).

Water-Soluble Amines

Behave like peptide hormones, cannot pass through the cell membrane, bind to surface receptors.

Fat-Soluble Amines

Act like steroid hormones, can pass through the cell membrane to bind to intracellular receptors.

Examples of Amine Hormones

Adrenaline (epinephrine), Thyroid hormones (T3, T4).

Steroid Hormones

Hormones derived from cholesterol, fat-soluble, can easily pass through the cell membrane.

Mechanism of Action for Steroid Hormones

Bind to intracellular receptors after passing through the cell membrane, and modulate gene expression directly.

Examples of Steroid Hormones

Estrogen, Testosterone, Cortisol.

G-protein coupled receptors

A type of receptor activated by peptide hormones that initiates second messenger systems.

cAMP

A second messenger involved in signaling pathways activated by peptide hormones.

Vasopressin

Also known as ADH, it regulates water balance in kidneys.

Epinephrine

Also known as adrenaline, it is involved in the fight or flight response.