Water-soluble hormone

Examples of Water-soluble hormone in the following topics:

• Mechanisms of Hormone Action

  • Hormones activate target cells by diffusing through the plasma membrane of the target cells (lipid-soluble hormones) to bind a receptor protein within the cytoplasm of the cell, or by binding a specific receptor protein in the cell membrane of the target cell (water-soluble proteins).
  • The reaction of the target cells may then be recognized by the original hormone-producing cells, leading to a down-regulation in hormone production.
  • Nuclear hormone receptors are activated by a lipid-soluble hormone such as estrogen, binding to them inside the cell.
  • Lipid-soluble hormones can cross the plasma membrane.
  • Water-soluble hormones, such as epinephrine, bind to a cell-surface localized receptor, initiating a signaling cascade using intracellular second messengers.

• Adrenal Medulla

  • The adrenal cortex is devoted to the synthesis of corticosteroid and androgen hormones.
  • These water-soluble hormones are the major hormones underlying the fight-or-flight response.

• Lipid-Derived, Amino Acid-Derived, and Peptide Hormones

  • All hormones in the human body can be divided into lipid-derived, amino acid-derived, and peptide hormones.
  • The primary class of lipid hormones in humans is the steroid hormones.
  • Steroid hormones are insoluble in water; they are carried by transport proteins in blood.
  • Amino acid-derived and polypeptide hormones are water-soluble and insoluble in lipids.
  • The structures of peptide hormones (a) oxytocin, (b) growth hormone, and (c) follicle-stimulating hormone are shown.

• Signaling Molecules

  • Other hydrophobic hormones include thyroid hormones and vitamin D.
  • Water-soluble ligands are polar and, therefore, cannot pass through the plasma membrane unaided; sometimes, they are too large to pass through the membrane at all.
  • Instead, most water-soluble ligands bind to the extracellular domain of cell-surface receptors.
  • These water soluble ligands are quite diverse and include small molecules, peptides, and proteins.
  • Compare and contrast the different types of signaling molecules:  hydrophobic, water-soluble, and gas ligands

• Solubility

  • The degree of solubility ranges widely depending on the substances, from infinitely soluble (fully miscible), such as ethanol in water, to poorly soluble, such as silver chloride in water.
  • For many solids dissolved in liquid water, solubility tends to correspond with increasing temperature.
  • In contrast, a non-polar solute such as naphthalene is insoluble in water, moderately soluble in methanol, and highly soluble in benzene.
  • Solubility increases with temperature for most substances; for example, more sugar will dissolve in hot water than in cold water.
  • Recognize the various ions that cause a salt to generally be soluble/insoluble in water.

• Gas Solubility and Temperature

  • Solubility of a gas in water tends to decrease with increasing temperature, and solubility of a gas in an organic solvent tends to increase with increasing temperature.
  • In general, solubility of a gas in water will decrease with increasing temperature: colder water will be able to have more gas dissolved in it.
  • When the temperature of a river, lake, or stream is raised abnormally high, usually due to the discharge of hot water from some industrial process, the solubility of oxygen in the water is decreased.
  • While it is in general true for gases dissolved in water, gases dissolved in organic solvents tend to become more soluble with increasing temperature.
  • Methane, oxygen, carbon monoxide, nitrogen, and helium all have different solubilities in water, but all of them become less soluble with increasing temperature.

• Food Requirements and Essential Nutrients

  • Fats are required in the diet to aid the absorption of fat-soluble vitamins and the production of fat-soluble hormones.
  • Vitamins fall into two categories: fat soluble and water soluble.
  • The fat-soluble vitamins dissolve in fat and can be stored in your body, whereas the water-soluble vitamins need to dissolve in water before your body can absorb them; therefore, the body cannot store them.
  • Water-soluble vitamins are not stored in the body; therefore, you need to have them more frequently.
  • Water-soluble vitamins are found in foods that include fruits, vegetables, and grains.

• Nephron, Parts, and Histology

  • The nephron of the kidney is involved in the regulation of water and soluble substances in blood.
  • A nephron is the basic structural and functional unit of the kidneys that regulates water and soluble substances in the blood by filtering the blood, reabsorbing what is needed, and excreting the rest as urine.
  • It is regulated by the neuroendocrine system by hormones such as antidiuretic hormone, aldosterone, and parathyroid hormone.
  • Unlike the other components of the nephron, its permeability to water is variable depending on a hormone stimulus to enable the complex regulation of blood osmolarity, volume, pressure, and pH.
  • However, anti-diuretic hormone (secreted from the pituitary gland as a part of homeostasis) will act on the distal convoluted tubule to increase the permeability of the tubule to water to increase water reabsorption.

• Solid Solubility and Temperature

  • Solubility often depends on temperature; the solubility of many substances increases with increasing temperature.
  • Many salts show a large increase in solubility with temperature.
  • A few, such as cerium(III) sulfate, become less soluble in water as temperature increases.
  • A useful application of solubility is recrystallizaton.
  • This chart shows the solubility of various substances in water at a variety of temperatures (in degrees Celsius).

• Absorption of Monosaccharides, Amino Acids, Dipeptides, Tripeptides, Lipids, Electrolytes, Vitamins, and Water

  • Glucose, amino acids, fats, and vitamins are absorbed in the small intestine via the action of hormones and electrolytes.
  • This occurs because the lipase is water-soluble, but the fatty triglycerides are hydrophobic and tend to orient towards each other and away from the watery intestinal surroundings.
  • The fat soluble vitamins A, D, and E are absorbed in the upper small intestine.
  • Of the water soluble vitamins, transport of Folate and B12 across the apical membrane are Na+ independent, but the other water soluble vitamins are absorbed by Na+ co-transporters.
  • In humans, electrolyte homeostasis is regulated by hormones such as antidiuretic, aldosterone, and parathyroid hormone.