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In most vertebrates, digestion is a multistage process in the digestive system, starting from ingestion of raw materials, most often other organisms. Ingestion usually involves some type of mechanical and chemical processing. Digestion is separated into four steps: Ingestion: placing food into the mouth (entry of food in the digestive system),
The function of the GI tract is to process ingested food by mechanical and chemical means, extract nutrients and excrete waste products. The GI tract is composed of the alimentary canal, that runs from the mouth to the anus, as well as the associated glands, chemicals, hormones, and enzymes that assist in digestion.
The chain of redox reactions driving the flow of electrons through the electron transport chain, from electron donors such as NADH to electron acceptors such as oxygen and hydrogen (protons), is an exergonic process – it releases energy, whereas the synthesis of ATP is an endergonic process, which requires an input of energy.
Metabolism (/ m ə ˈ t æ b ə l ɪ z ə m /, from Greek: μεταβολή metabolē, "change") is the set of life-sustaining chemical reactions in organisms.The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks of proteins, lipids, nucleic acids, and some carbohydrates; and the ...
Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms, ingestion takes place by absorbing a substance through the cell membrane.
Cellular respiration is a vital process that occurs in the cells of all [[plants and some bacteria ]]. [2] [better source needed] Respiration can be either aerobic, requiring oxygen, or anaerobic; some organisms can switch between aerobic and anaerobic respiration. [3] [better source needed]
Extracellular phototropic digestion is a process in which saprobionts feed by secreting enzymes through the cell membrane onto the food. The enzymes catalyze the digestion of the food, i.e., diffusion, transport, osmotrophy or phagocytosis. Since digestion occurs outside the cell, it is said to be
In the liver, muscles, and the kidney, this process occurs to provide glucose when necessary. [12] A single glucose molecule is cleaved from a branch of glycogen, and is transformed into glucose-1-phosphate during this process. [1] This molecule can then be converted to glucose-6-phosphate, an intermediate in the glycolysis pathway. [1]