Hormones and their differences
Hormones are released by glands and acts as chemical messengers that allow interaction between cells. The endocrine system enables the secretion of hormones to maintain homeostasis and other processes, for instance, development and reproduction in a living organism. There are two general sub-classes of hormones, Lipid soluble hormones and water-soluble hormones. Lipid-soluble hormones diffuse through the plasma membrane and enter the target cell to form a bond with a receptor protein while water-soluble hormones form binds with receptor protein on the plasma membrane of the cell.
Structural Differences
More than a few lipid-soluble hormones are generated from saturated fats, thus are similar in structural formation. Lipid hormone class in humans is primarily steroid hormones. Chemically, steroids are alcohols or ketones and end in –ol for alcohol and –one for ketones. For instance, female sex hormone and male sex hormone and are produced in the reproductive organs in both females and males. Due to a strong structural bond that makes steroid insoluble in water enables it to circulate longer than water-soluble hormones.
Water-soluble hormones as stated, can dissolve in water since they are formed from amino acids which are the structural unit of proteins. An example of a water-soluble hormone is epinephrine which is an amino acid derivative and is stored in endocrine cells till their need arises. Binding to protein receptors gives signals to the molecules inside the cell to activate enzymes, thus influences gene appearance.
Transport Differences
Lipid soluble hormones like estrogen, testosterone binds to a carrier protein for easy transportation in the blood. However, other small spherical particles like cholesterol and triglycerides are transported through the body by trapping lipophilic molecules in their midpoints. Thus, by binding, lipid-soluble hormones form a polar nature that enables free movement via the target membrane to initiate a response.
Unlike lipid-soluble hormones, water-soluble hormones are transported freely within the bloodstream. This is as a result of their solubility nature and does not require proteins to bind. Yet, for such hormones to enter a cell, they bind with a membrane receptor since diffusion through the lipid bilayer requires substances with polar nature.
The difference in Receptor Binding
There are two types of receptors, intracellular and extracellular receptors. Intracellular receptors are located inside the cell and exist freely as soluble components of the cytoplasm. Therefore, lipid-soluble hormones such as steroids can bind with such receptors internally to initiate a series of cellular effects resulting in modified characteristics. Lipid soluble hormones require receptor binding to facilitate a cellular activity.
Extracellular receptors are located on the plasma membrane of the cell. This indicates that water-soluble hormones can bind to a receptor protein externally on the plasma membrane to stimulate a change of activities in the cell. Theses extracellular receptors do not exist freely as compared to intracellular receptors.
Differences in Hormone Action
Lipid soluble hormones stimulate adjacent cells by diffusing through the specific cell membrane to bind a receptor protein within the cytoplasm of the cell and bring change in gene expression and transcription. This is achieved by inducing the production of protein molecules that affects the long-term structural formation and functions of the cell.
However, water-soluble hormones bind externally with the specific receptor protein on the plasma membrane to stimulate varied behaviours and responses. Alternatively, receptor stimulation results in a change of the cell activities that enable intracellular to receive signals by informing the original hormone-producing cell.