Aerobic and Anaerobic respiration

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Aerobic Respiration All living things need to have a source of chemical energy in order to live. A fuel is a substance that can be used as a source of chemical energy. Animals eat food as their fuel. Plants make food to act as their fuel, using the energy of sunlight and a process called photosynthesis. Both animals and plants then release the energy from food by using the process of respiration. Respiration in mammals usually involves oxygen, hence the name aerobic respiration as opposed to anaerobic respiration (without oxygen). The following equation summarises what happens during respiration. ATP is a molecule that contains a lot of energy. It is present in every cell. When a cell requires more energy, ATP is broken down to release its energy. Respiration occurs in organelles (structures within a cell) called mitochondria (singular ‘mitochondrion’). Anaerobic Respiration When muscles are required to use energy at a rate faster than oxygen can be delivered by the blood, they respire anaerobically (without oxygen). Mammals can only respire anaerobically for short periods of time as it produces lactic acid that is toxic to cells. Cramp is a common phenomena experienced when respiring anaerobically. Anaerobic respiration can be summarised by the following equation: Anaerobic respiration is considered ‘wasteful’ respiration because the total energy yield from each glucose molecule is only a fraction of what is released when compared to aerobic respiration. Breathing Breathing (or ventilation) is not the same as respiration. Movements of the ribs, rib muscles and diaphragm draws air into and out of the lungs. When we breathe in, we inhale. When we breathe out, we exhale. This provides the body with the oxygen required for respiration. How oxygen gets into the blood Air passes between the lungs and the outside of the body through the windpipe (called the trachea). The trachea divides into two bronchi, with one bronchus for each lung. Each bronchus divides further in the lungs into smaller tubes called bronchioles. At the end of each bronchiole there are groups of tiny air sacs. These air sacs have bulges called alveoli to increase their surface area and speed up the exchange of gases.

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