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Control of internal environment of living organisms.

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Introduction

Control of internal environment of living organisms. It is very important that the internal environment of living organisms is kept constant, as the cells inside the body need this constant environment to work efficiently, failure to do so could result in death. Therefore no matter what is happening in the external environment homeostasis keeps the environment around the cells the same. Examples of things that are controlled are respiratory gases (oxygen and carbon dioxide), pH, the concentration of nutrients and waste products, the concentration of salts and other small ions, the volume and pressure of blood plasma and temperature (humans sweat to lower body temperature). ...read more.

Middle

When the detector finds that the value is higher then should be it sends information to an effector which will then correct the level. This happens till the detector finds the value is too low and the effector then changes what it is doing so the value then rises. Information is therefore feed back to the detector from the effector, the feedback is called negative due to it stopping the effector doing one thing and stimulating it to do the opposite. ...read more.

Conclusion

The information travels along nerves (temperature regulation) or in the blood as chemicals called hormones (regulation of water content). Hormones are secreted by endocrine glands also know as ductless glands as they do not have a duct for carrying the secretion to a particular point. The hormones pass into the blood which then flows through the capillaries and to the glands. There are three different main groups of animal hormones - * Amino acids (and catecholamines): All water-soluble molecules (thyroxine and adrenaline) * Proteins: Water soluble (insulin and glucagon) * Steroids: Lipids. Fat soluble molecules, made from cholesterol (oestrogen and testosterone) ...read more.

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