Hormone Classification & Properties

Steroids are a type of hormone that are derived from cholesterol and have a characteristic structure of four carbon rings. Progesterone is a steroid hormone that is primarily involved in the female reproductive system, playing a crucial role in regulating the menstrual cycle and supporting pregnancy. It is produced by the ovaries, placenta, and adrenal glands. Unlike peptide hormones, which are made up of amino acids, progesterone is a lipid-soluble hormone that can easily pass through cell membranes to bind to intracellular receptors. Therefore, the correct answer is steroid.

Steroids are a type of hormone that are derived from cholesterol and are characterized by their four-ring structure. Testosterone, being a hormone produced primarily in the testes, is classified as a steroid hormone. Steroids are known for their ability to regulate various physiological processes in the body, including growth, metabolism, and reproduction. They exert their effects by binding to specific receptors inside cells, which then initiate a cascade of cellular responses. Therefore, the correct answer is steroid.

Thyroxine is a hormone produced by the thyroid gland and is classified as a thyroid hormone. It is not a monoamine, peptide, protein, steroid, or eicosanoid hormone. Thyroid hormones play a crucial role in regulating metabolism, growth, and development in the body.

Testosterone, notice the 4-ring structure and its conformation, which is present in all steroids.

Peptide (Protein) Hormones are a type of hormone that are made up of amino acids and are typically produced and released by endocrine glands. Insulin, a hormone released by the pancreas, is a peptide hormone. It plays a crucial role in regulating blood sugar levels by facilitating the uptake of glucose into cells. Peptide hormones are water-soluble and bind to specific receptors on the surface of target cells, triggering a series of intracellular signaling events. This ultimately leads to the desired physiological response.

Steroids are synthesized from cholesterol. Cholesterol is a precursor molecule that is converted into various steroid hormones, such as cortisol, aldosterone, estrogen, and testosterone. These hormones play important roles in regulating various physiological processes in the body, including metabolism, inflammation, and reproduction. Therefore, the statement that steroids are synthesized from cholesterol is correct.

Estradiol is a type of hormone that belongs to the steroid category. Steroid hormones are derived from cholesterol and are characterized by their ability to pass through the cell membrane and bind to specific receptors in the nucleus. Estradiol, being a steroid hormone, plays a crucial role in the development and regulation of the female reproductive system. It is responsible for the development of secondary sexual characteristics, regulation of the menstrual cycle, and maintenance of pregnancy.

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Eicosanoids are a group of lipid signaling molecules that are derived from arachidonic acid. They play important roles in inflammation, immune response, and regulation of blood pressure. Unlike the other options listed, eicosanoids are not classified as monoamine, peptide, protein hormones, steroids, or thyroid hormones. Therefore, the correct answer is eicosanoids.

Thyroxine, notice the IODINE atoms.

It's gigantic! The amino acids are numbered - this kind of numbering will mean the chemical is a protein. Also notice the clear denotation of the COOH at the carboxy terminus and the NH2 of the amine terminus.

Eicosanoids are a class of signaling molecules that are derived from fatty acids and have diverse biological functions. They include prostaglandins, which are involved in inflammation and pain, as well as other important processes such as blood clotting and regulation of blood pressure. Eicosanoids are not considered monoamine, peptide, protein, steroid, or thyroid hormones. Therefore, the correct answer is eicosanoid.

Peptide (Protein) Hormones are the correct answer because they are a type of hormone that is made up of amino acids and are synthesized in the endocrine glands. They are typically released into the bloodstream and act on target cells by binding to specific receptors on the cell surface. Examples of peptide hormones include insulin, growth hormone, and oxytocin. Monoamines are a different type of hormone that are derived from amino acids, but they are not the correct answer in this case. Steroids, thyroid hormones, and eicosanoids are also not the correct answer as they are different types of hormones.

Epinephrine is classified as a monoamine. Monoamines are a type of neurotransmitter and hormone that are derived from amino acids. They are characterized by a single amine group in their chemical structure. Epinephrine, also known as adrenaline, is produced by the adrenal glands and acts as a hormone and neurotransmitter in the body. It plays a crucial role in the "fight or flight" response, increasing heart rate, blood pressure, and energy levels in response to stress or danger.

Monoamines are a class of neurotransmitters that includes melatonin, serotonin, and dopamine. These molecules are derived from amino acids and play important roles in regulating mood, behavior, and various physiological processes in the body. Melatonin is involved in regulating the sleep-wake cycle, serotonin is involved in mood regulation and cognition, and dopamine is involved in reward and motivation. Therefore, the correct answer is monoamines because it accurately categorizes these three neurotransmitters.

Eicosanoids are a type of signaling molecules that are derived from fatty acids and play a role in mediating various physiological processes such as inflammation, vasoconstriction or vasodilation, coagulation, pain, and fever. They are not classified as monoamines, peptide hormones, steroids, or thyroid hormones, but rather as a separate category of signaling molecules.

Epinephrine (adrenaline), made by modifying the amino acid tyrosine.

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Eicosanoids are a type of hormone derived from fatty acids that play a crucial role in inflammation, immunity, and various physiological processes. Unlike monoamines, peptides, steroids, and thyroid hormones, eicosanoids are not derived from amino acids or cholesterol. They are synthesized from arachidonic acid and include prostaglandins, leukotrienes, and thromboxanes. Eicosanoids are known for their local and short-lived effects, acting as signaling molecules in a paracrine or autocrine manner. Therefore, eicosanoids are the correct answer in this context.

Peptide (Protein) hormones are the correct answer because they are a type of tropic hormone. Tropic hormones are hormones that regulate the secretion of other hormones in the body. Peptide hormones are made up of amino acids and are produced by various glands in the body, such as the pituitary gland and the pancreas. They act by binding to specific receptors on target cells and triggering a series of intracellular signaling pathways. Examples of peptide hormones include insulin, growth hormone, and follicle-stimulating hormone.

Melatonin, a modified version of the amino acid tryptophan.

Monoamine neurotransmitters are able to pass the blood-brain barrier. The blood-brain barrier is a protective barrier that separates the blood vessels from the brain tissue, preventing the entry of many substances into the brain. However, monoamine neurotransmitters, such as dopamine, serotonin, and norepinephrine, are able to cross this barrier and act on receptors in the brain. This ability allows them to play important roles in regulating mood, behavior, and other brain functions.

Monoamines and peptide (protein) hormones are hydrophilic because they are water-soluble and can easily dissolve in water. Hydrophilic substances have an affinity for water and can form hydrogen bonds with water molecules. On the other hand, steroids and thyroid hormones are hydrophobic because they are lipid-soluble and cannot dissolve in water. Eicosanoids can be either hydrophilic or hydrophobic depending on their specific structure.

Steroids and thyroid hormones must bind to binding globulins (transport proteins) in order to circulate through the body. Binding globulins play a crucial role in transporting these hormones in the bloodstream, protecting them from degradation and ensuring their delivery to target tissues. This binding also helps regulate the concentration and availability of these hormones in the body.