Tag: endocrine system in humans

Chemically, hormones may be proteins, polypeptide's, amino acid derivatives or steroids. They help the body to cope up with infections, stress. trauma, starvation and extreme temperatures.

• Hormones have diverse chemical structures, mainly of three classes: eicosanoids, steroids, and amino acid/protein derivatives (amines, peptides, and proteins). 
• The glands that secrete hormones comprise the endocrine signalling system. The term hormone is sometimes extended to include chemicals produced by cells that affect the same cell (autocrine or intracrine signalling) or nearby cells (paracrine signalling). Hence, Chemically, hormones are Proteins and Steroids.

• Hormones are derivative of protein, amino acids, and steroids. Hormones are the chemical messenger that provide signals to the cell for performing the particular function. Hormones are used up completely in the metabolism.
• Enzymes are the catalyst, which enhances the biochemical reactions. Enzymes act at the place where they are formed. And enzymes do not get used up in the reaction. Hence, Hormones differ from enzymes in the respect that they are used completely in metabolism.

• A hormone may be defined as a specific product (organic substance) of an endocrine gland secreted into the blood which carries it to a specific part of the body where it produces a definite physiological effect. 
• Hormones exert their effects not where they are locally produced, but on other tissues of the body. And never stored in the body and synthesized at once.  Hence,  They have a high molecular weight and not found in plants is not the property of hormones.

• A hormone receptor is a receptor molecule that binds to a specific hormone.
• Hormone receptors are a wide family of proteins made up of receptors for thyroid and steroid hormones, retinoids and Vitamin D, and a variety of other receptors for various ligands, such as fatty acids and prostaglandins. Hence, Hormones affect distant cells by controlling Receptor proteins.  

A hormonal control is always involuntary. We cannot control its action by our wish. Eg$:$ Growth of height of an individual.

FSH and LH are collectively known as gonadotropic hormone because they regulate the growth and functioning of gonads.

The calorigenic effect is a result of the increased metabolic rate and increased oxygen consumption by cells. When the metabolic rate increases, more heat is generated.T1 and T1 are hormones that have a calorigenic effect.

Hypothalamus secretes both releasing and inhibitory hormones controlling the secretion of some anterior pituitary hormones(LH, ACTH, and TSH etc.)

IAA (auxin), GA3 (gibberellin), and ABA (abscisic acid) are naturally occurring plant hormones. Synthetic hormones include 2,4-D and NAA.