1. Cardiovascular and respiratory
2. nervous and respiratory
3. respiratory and cardiovascular
4. digestive and cardiovascular
5. digestive and muscular
The respiratory system facilitates gas exchange between cells and the environment. The structures involved include the nasal passage, the trachea, and the lungs.
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. The lungs accomplish this by passing large amounts of blood over gas exchange membranes. In fact, the body’s whole blood volume passes over these membranes about once per minute!
It could be argued that the respiratory system is one of the body’s most important. Without oxygen to fuel cellular respiration, cells begin to die within minutes. This is the primary reason that heart attacks are deadly. 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. When the circulatory system stops working, our tissues begin to die from lack of oxygen. The lungs also expel carbon dioxide – a waste product of cellular respiration – which could otherwise build up to toxic levels.
Digestive System
The respiratory system facilitates gas exchange between cells and the environment. The structures involved include the nasal passage, the trachea, and the lungs.
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. The lungs accomplish this by passing large amounts of blood over gas exchange membranes. In fact, the body’s whole blood volume passes over these membranes about once per minute!
It could be argued that the respiratory system is one of the body’s most important. Without oxygen to fuel cellular respiration, cells begin to die within minutes. This is the primary reason that heart attacks are deadly. 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. When the circulatory system stops working, our tissues begin to die from lack of oxygen. The lungs also expel carbon dioxide – a waste product of cellular respiration – which could otherwise build up to toxic levels.
Digestive System
The digestive system ingests food and breaks it down into usable nutrients before excreting solid waste products. It includes the mouth, esophagus, stomach, and intestines.
The digestive system takes in food and processes it to obtain useful nutrients that the body can use for fuel. 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. 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.
When food enters the body, it is first chewed by the mouth to break it down into a mush that stomach acids can penetrate. In the stomach, it is treated with acids and special enzymes that break the food’s components down into more useful forms.
Finally, 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. The digestive system also expels solid waste components of our food that our body can’t use in the form of fecal matter.
Cardiovascular/Circulatory System
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. These substances include oxygen, nutrients, hormones, and waste products. The cardiovascular system includes the heart, the blood, and the blood vessels.
The cardiovascular system is a highly efficient system for moving substances around the body. 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.
