Steroid hormones are nonpolar hormones that require carrier proteins in order to travel through the bloodstream. Once they reach their target cell, they are able to enter the cell's nucleus and affect the transcription of certain genes. Since steroid hormones are derived from cholesterol they are small and nonpolar, allowing them to freely diffuse across the membrane without protein mediation.

In contrast, peptide hormones and tyrosine derivatives are unable to freely cross the membrane due to size. Since these hormones cannot directly enter the cell, they generally initiate second messenger signal cascades. Peptide hormones are able to freely circulate, while tyrosine derivatives bind to carrier proteins in the blood.

Cortisol is the only steroid hormone listed, some other examples would be estrogen and androgens. Insulin and parathyroid hormones are peptide hormones. Epinephrine is a catecholamine, which is a tyrosine derivative.

Estrogen, androgen, progesterone, cortisol, and aldosterone are all steroid hormones. Thyroid-stimulating hormone belongs to the class of hormones that are proteins, glycoproteins, and peptide hormones. Specifically, thyroid-stimulating hormone is a glycoprotein.

Eicosanoids are local paracrine and autocrine agents that play an important role in inflammation. The eicosanoids include the thromboxanes, lipoxins, leukotrienes, and the prostaglandins.

Insulin belongs to the "proteins and peptides" class of hormones. The proteins and peptides are water-soluble hormones. Thyroid hormones, all steroids, retinoids, prostaglandins and vitamin D are all examples of lipid-soluble hormones. Note that even though thyroid hormones are derived from the amino acid tyrosine, they are insoluble in water, and are carried in the blood by proteins.

A direct hormone binds to its target organ and effects an immediate change. A tropic hormone causes a secondary messenger pathway to commence and effects a change at the end of the pathway resulting in the release of another hormone. Hydrophobic hormones refer to lipophilic molecules, while hydrophilic molecules are the opposite. An example of this is adrenocorticotropic hormone (ACTH) released from the anterior pituitary. It's target is the adrenal cortex, and its action is to stimulate the adrenal cortex to release cortical hormones.

Peptide hormones are large polar hormones that are able to freely float in the bloodstream. Once they reach their target cells, peptide hormones attach to transmembrane receptors on the target cell. This generally initiates a second messenger signal cascade to amplify the response, eventually driving a change in genetic expression and transcription.

In contrast, steroid hormones are small and nonpolar. These characteristics allow them to freely diffuse across the plasma membrane of the cell and enter the nucleus, where they can directly act as transcription factors to regulate genetic expression.

忧郁ersecretion, or oversecretion, of the growth hormone in adulthood results in a condition called acromegaly. The adult individual no longer has growth plates at this point, so the excess hormones interact with the receptors on the surface of bones. This results in coarse facial features, thickening of the dermis, and large hands and feet.

Gigantism is also a result from hypersecretion of the growth hormone, but it occurs during childhood when the individual still has his or her growth plates. Dwarfism is a result from hyposecretion, or undersecretion, of the growth hormone.

Gastrin is a hormone secreted by the stomach and small intestine that acts on the gastrointestinal tract and pancreas. Many hormones, such as vasopressin (antidiuretic hormone) and aldosterone act on the kidneys. Hormones that target bone are calcitonin and parathyroid hormone. Hormones that target gonads include follicle stimulating hormone and luteinizing hormone.

The heart secretes atrial natriuretic peptide, which acts on the kidneys. Oxytocin is secreted by the posterior pituitary. Thymosin is secreted by the thymus gland. Androgens are secreted by the adrenal cortex.