![]() Electrons generated in the Krebs cycle move across the folds in the inner membrane (cristae) that separate the mitochondrial matrix (inner compartment) from the intermembrane space (outer compartment). Krebs Cycle: Two additional molecules of ATP are produced in this cycle along with CO 2, additional protons and electrons, and the high energy molecules NADH and FADH 2.In the presence of oxygen, pyruvate enters the inner matrix of cell mitochondria and undergoes further oxidation in the Krebs cycle. Two molecules of ATP and two molecules of the high energy NADH are also produced in glycolysis. Glycolysis occurs in the cytoplasm and involves the oxidation or splitting of glucose into pyruvate.RegisFrey/Wikimedia Commons/ CC BY-SA 3.0Īerobic cellular respiration consists of three stages: glycolysis, citric acid cycle (Krebs Cycle), and electron transport with oxidative phosphorylation. This is diagram of aerobic cellular respiration including glycolysis, Krebs cycle (citric acid cycle), and the electron transport chain. ATP generated in the process provides the energy needed to perform normal cellular functions, such as macromolecule synthesis, muscle contraction, cilia and flagella movement, and cell division. From there, CO 2 diffuses into blood plasma and red blood cells. Carbon dioxide and water formed in the process diffuse into the interstitial fluid surrounding cells. Through a series of steps, glucose and oxygen are converted to carbon dioxide (CO 2), water (H 2O), and the high energy molecule adenosine triphosphate (ATP). In cellular respiration, glucose obtained from digestion is split into its constituent parts for the production of energy. As blood is circulated throughout the body, nutrients are transported to body cells. ![]() This is accomplished through the digestive process where food is broken down and nutrients are absorbed into the blood. In order to access the energy stored in the foods we eat, biological molecules composing foods ( carbohydrates, proteins, etc,) must be broken down into forms that the body can utilize. ![]() The oxygen obtained from internal respiration is used by cells in cellular respiration. Credit: Encyclopaedia Britannica/UIG/Getty Images The three processes of ATP production or celluar respiration include glycolysis, the tricarboxylic acid cycle, and oxidative phosphorylation. While oxygen is being dropped off at cells, carbon dioxide is being picked up and transported from tissue cells to the lungs. Oxygen rich blood is transported by the circulatory system from lung capillaries to body cells and tissues. At the same time, carbon dioxide diffuses in the opposite direction (from the blood to lung alveoli) and is expelled. Oxygen within the lungs diffuses across the thin epithelium of lung alveoli (air sacs) into surrounding capillaries containing oxygen depleted blood. This includes contraction and relaxation of the diaphragm and accessory muscles, as well as breathing rate.Įxternal respiratory processes explain how oxygen is obtained, but how does oxygen get to body cells? Internal respiration involves the transportation of gases between the blood and body tissues. External respiration in mammals encompasses the mechanical processes related to breathing. In the human body, oxygen is taken into the lungs by inhalation and carbon dioxide is expelled from the lungs by exhalation. Humans and other mammals have a respiratory system with specialized respiratory organs ( lungs) and tissues. Insects and spiders have respiratory organs called tracheae, while fish have gills as sites for gas exchange. In organisms such as nematodes (roundworms), gases and nutrients are exchanged with the external environment by diffusion across the surface of the animals body. Others either have organs specialized for gas exchange or have a complete respiratory system. ![]() Animals that lack specialized organs for respiration rely on diffusion across external tissue surfaces to obtain oxygen. In animal organisms, the process of external respiration is performed in a number of different ways. One method for obtaining oxygen from the environment is through external respiration or breathing. Wetcake/DigitalVision Vectors/Getty Images External Respiration When exhaling the diaphragm relaxes and the lungs contract, moving the chest back down. When inhaling, the diaphragm contracts and the lungs expand, pushing the chest upwards.
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