![]() ![]() The body’s entire blood volume takes about a minute to circulate – making this a truly high-speed expressway for distributing oxygen, nutrients, messages, and removing waste. The cardiovascular system is a highly efficient system for moving substances around the body. The cardiovascular system includes the heart, the blood, and the blood vessels. ![]() These substances include oxygen, nutrients, hormones, and waste products. The cardiovascular system (sometimes called the circulatory system, which could also include the lymphatic system) is responsible for the transport of materials through the body. Once the nutrients have been extracted from foods, they are distributed to the body’s cells by the circulatory system. The liver helps the process of digestion by releasing substances that assist the stomach and intestines in breaking down food, and by breaking down toxic substances in the blood. The digestive system also expels solid waste components of our food that our body can’t use in the form of fecal matter. ![]() In the stomach, it is treated with acids and special enzymes that break the food’s components down into more useful forms.įinally, it passes through the intestines: being squeezed through the huge surface area of the lower gastrointestinal tract to ensure as many useful nutrients are extracted from the food as possible. When food enters the body, it is first chewed by the mouth to break it down into a mush that stomach acids can penetrate. We can also get other important nutrients from food, such as essential amino acids (amino acids our bodies can’t make themselves), vitamins, and minerals that our cells need to make important biomolecules. Carbohydrates, proteins, and fats can all be used by our cells to obtain the energy they need to stay alive and carry out their functions. The digestive system takes in food and processes it to obtain useful nutrients that the body can use for fuel. It includes the mouth, esophagus, stomach, and intestines. The digestive system ingests food and breaks it down into usable nutrients before excreting solid waste products. The lungs also expel carbon dioxide – a waste product of cellular respiration – which could otherwise build up to toxic levels. When the circulatory system stops working, our tissues begin to die from lack of oxygen. Although the heart is part of the circulatory system, not the respiratory system, it is responsible for transporting oxygen from the lungs to our cells. This is the primary reason that heart attacks are deadly. Without oxygen to fuel cellular respiration, cells begin to die within minutes. It could be argued that the respiratory system is one of the body’s most important. In fact, the body’s whole blood volume passes over these membranes about once per minute! The lungs accomplish this by passing large amounts of blood over gas exchange membranes. The respiratory system takes oxygen from the environment to be used throughout the body. In humans, oxygen is taken into the body by the lungs, where it and rapidly diffuses into the blood. ![]()
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