what is animal hormone
Answers
Answer:
Explanation:
Hormones are chemicals secreted by various endocrine glands directly into the blood and transported to the respective organs, where they act by regulating various metabolic processes. The target cells have specific receptors to recognize the respective hormones
Vertebrate Endocrine Glands and Hormones
growth hormone: stimulates growth factors.
adrenocorticotropic hormone (ACTH): simulates adrenal glands to secrete glucocorticoids such as cortisol.
thyroid-stimulating hormone: stimulates thyroid gland to secrete thyroid hormones.
All multicellular organisms produce hormones including plants. The best-known animal (and human) hormones are those produced by endocrine glands of vertebrate animals, but hormones are produced by nearly every organ system and tissue type in a human or animal body.
Explanation:
Hormones are the chemical integrators of a multicellular existence, coordinating activities from daily maintenance to reproduction and development. The neurotransmitters released by axons are one class of chemical communicators that act on an adjacent cell, usually a muscle cell or another neuron. Hormones are a mostly distinct class of chemical communicators secreted by nerves, ordinary tissue, or special glands; they act on cells far removed from the site of their release. They can be proteins, single polypeptides, amines, or steroids or other lipids. Hormones travel to their place of action via the circulatory system and then match their particular configuration with a specific receptor molecule attached to a cell membrane or, more usually, located within the cell.
The nervous system coordinates the more rapid activities of animal life, such as movement, while the hormones integrate everything else. Only the larger, more complex animals, such as vertebrates and some arthropods, have special endocrine glands to produce hormones; other animals use nerve cells or tissues such as the gonads. Endocrine glands are another example of a partitioning of functions into separate organs, a system that increases efficiency but that requires a relatively large size to maintain. Greater specialization is also associated with greater difficulties in regenerating lost parts or preventing breakdowns in functions.
Although the list of hormones found in the mammalian body may seem large, the numbers are surprisingly low for the variety of functions they influence. Which of the multiple functions any one hormone regulates depends on the specificity of the receptors on or within cells. Because all hormones bathe all cells as a result of their transport by the circulatory system, it is more efficient to have a general messenger transported to a cell, where it elicits only one of many possible outcomes. As in the nervous system, the specificity of response lies in the organ that responds and not with the messenger that merely commands action.
Chemicals that allow communication among individuals are called pheromones. Sexual attractants are the most common, but there are many other kinds.
Digestion
In contrast to plants, the essential nutrients that animals require to sustain life and to reproduce come packaged with their source of energy—the flesh or organic remains of other organisms. More complex animals tend to shorten and even eliminate many synthetic pathways, because most of the essential building blocks of their own complex molecules are present in their food. Reducing synthetic flexibility, however, inhibits a radical alteration in diet. The digestive and synthetic chemistry of animals strongly reflects their diets; some of this design may be altered with diet, and some may not. No matter how many leafy vegetables humans consume, for example, the cellulose remains undigested because appropriate microorganisms are not present in the digestive tract and they cannot be obtained at will. Consequently, essential nutrients are species-specific and tend to include only molecules adequately available in the usual diet.
The structure of a digestive system reflects its typical diet. Its purpose is to process food only to the point at which it can be transported to other cells for use as either fuel or structural material. In the simplest animals, such as sponges or some coelenterates, digestion is entirely intracellular, and some of the products of digestion are transported to nondigestive cells. As animals began to catch larger types of food, more of the digestive process had to be handled extracellularly. At the simplest level, seen in coelenterates or flatworms, large food items are held in an internal cavity (the gut) or even externally where certain cells release digestive enzymes. The food is broken down only to the stage at which it can be ingested by cells, which finish the process intracellularly. In more complex animals extracellular digestion accounts for virtually all breakdown of food before the products are transported to nondigestive cells.
Chemical digestion, whether intracellular or extracellular, is a relatively slow way to decompose a large item. Thus, animals begin to break it apart mechanically before exposing it to digestive enzymes. Teeth, the molluscan radula, and muscular gizzards are organs that speed up the digestive process by macerating food into finer particles.
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