Why are feces not metabolic waste

am Puls Biologie 5, textbook

97 Animal Physiology The constancy of the inner milieu is vital. The term “milieu” describes our social environment in everyday life, in biology the term has a different meaning: The outer milieu, the environment, differs from the inner milieu, i.e. the composition of the body's interior. The inner milieu is of great importance: All cells of animals live in a watery world, the so-called tissue fluid, which fills all cavities in the body. The composition of the tissue fluid is decisive for the survival of the cells. Factors such as the water content, the content of salts and other ingredients, the pH value, etc. must be regulated very precisely. This maintenance of the inner milieu is called homeostasis 1. All organ systems of the metabolism are involved in homeostasis (k Fig. 3), regulation and control takes place via the hormonal system and the vegetative nervous system. This process probably doesn't seem very exciting and natural to you, but homeostasis is the basis for the survival and functioning of our body. Have you ever tried to exercise vigorously after a heavy meal? If so, you probably did not fare well. This is because you disrupted the regulation of homeostasis! Maintaining the inner milieu, homeostasis, is a vital process. Structure and function Control and regulation Nutrients Stomach, Heart, Tissue fluid, Mouth, Intestines, Heat energy After Undigested (feces), Metabolic waste (urine), Food, CO 2 CO 2 CO 2 O 2 O 2 O 2 circulatory system waste materials waste materials nutrients lungs kidney blood cells respiratory system The spongy tissue of the lungs provides a moist surface of about 100m 2 for gas exchange. Skin The exchange area of ​​the skin in humans is around 2m 2. Digestive system The lining of the small intestine has villi to increase the surface area (see p. 88), which together with folds and microvilli provide an exchange area of ​​30 to 40m 2. Excretion system In the kidney, a million clusters of vessels (see SEM image) clean the blood and provide 0.3m 2 of filtration area for this. Fig. 3: Organ systems in metabolism. The skin, lungs, intestines and kidneys exchange substances between the organism and the environment. The circulatory system connects all organs and thus has a central role. Glossary 1 Homeostasis: from the Greek homoiostásis (= equality), in general the maintenance of a state of equilibrium in an open system. This term is also used in other natural science subjects, but also, for example, in psychology or law. Basic concept of structure and function: Substances can be exchanged thanks to large surfaces. In the kidneys as well as in the digestive and respiratory systems, surface enlargement occurs through certain structures (see p. 100, 106). Control and regulation: Homeostasis is the regulation mechanism that is necessary so that all other control and regulation processes can run at all. A balanced inner milieu must be ensured so that, for example, the conduction of nerves works, so that hormones remain functional, so that the proteins in the cell membranes retain their shape, etc. The energy required for this is our basic metabolic rate, that is, the energy that we also consume in complete peace. Exercise W 1 Basal metabolic rate and energy requirement: For an average adult, the basal metabolic rate is around 10,000 kJ per day. Search the Internet for a basal metabolic rate calculator that allows you to calculate the basal metabolic rate of a person based on body weight, height, age and gender. Calculate your own energy needs. Vary the parameters and compare the values. For testing purposes only - property of the publisher öbv

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