Respiratory System - Respiration In Insects, Respiratory System Of Fish, Respiration In Terrestrial Vertebrates, Human Respiratory System - Respiration in the earthworm
surface cells oxygen animals
Aerobic organisms take in oxygen from the external environment and release carbon dioxide in a process known as respiration. At the most basic level, this exchange of gases takes place in cells and involves the release of energy from food materials by oxidation. Carbon dioxide is produced as a waste product of these oxidation reactions. The gas exchange in cells is called cellular respiration. In single-celled organisms, the oxygen and carbon dioxide simply diffuse through the cell membrane. Respiration in multicellular organisms, however, is a much more complex process involving a specialized respiratory system that plays an intermediary role between the cells and the external environment. While the respiratory organs of some complex organisms such as insects communicate directly with internal tissues, respiration in vertebrates also involves the circulatory system, which carries gases between cells and respiratory organs.
The respiratory system must meet two important criteria. First, the respiratory surface must be large enough to take in oxygen in sufficient quantities to meet the organism's needs and release all waste gas quickly. Some animals, such as the earthworm, use the entire body surface as a respiratory organ. The internal respiratory organs of vertebrates generally have many lobes to enlarge the surface area. Second, the respiratory membrane must be moist, since gases require water to diffuse across membranes. The watery environment keeps the respiratory surface moist for aquatic animals. A problem exists for land animals, whose respiratory surfaces can dry out in open air. As a result, animals such as the earthworm must live in damp places. Internal respiratory organs provide an environment that is easier to keep moist.
The earthworm uses its moist outer skin as a respiratory organ. Oxygen diffuses across the body surface and enters blood in the dense capillary mesh that lies just below the skin. Blood carries the oxygen to the body cells. There, it picks up carbon dioxide and transports it to the skin capillaries where it diffuses out of the body. The skin is effective as an organ of respiration in small wormlike animals where there is a high ratio of surface to volume.
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Gills mediate the gas exchange in fish. These organs, located on the sides of the head, are made up of gill filaments, feathery structures that provide a large surface for gas exchange. The filaments are arranged in rows in the gill arches, and each filament has lamellae, discs that contain capillaries. Blood enters and leaves the gills through these small blood vessels. Although gills are restric…
Lungs are the internal respiratory organs of amphibians, reptiles, birds, and mammals. The lungs, paired invaginations located in one area of the body, provide a large, thin, moist surface for gas exchange. Lungs work with the circulatory system, which transports oxygen from inhaled air to all tissues of the body. The circulatory system also transports carbon dioxide from body cells to the lungs t…
The human respiratory system consists of the respiratory tract and the lungs. The respiratory tract can again be divided into an upper and a lower part. The upper part consists of the nose, nasal cavity, pharynx (throat) and larynx (voicebox). The lower part consists of the trachea (windpipe), bronchi, and bronchial tree. The respiratory tract cleans, warms, and moistens air during its trip to the…
The lungs are two cone-shaped organs located in the thoracic cavity, or chest, and are separated by the heart. The right lung is somewhat larger than the left. The pleural membrane surrounds and protects the lungs. One layer of the pleural membrane attaches to the wall of the thoracic cavity, and the other layer encloses the lungs. A fluid between the two membrane layers reduces friction and allow…
Pulmonary ventilation, or breathing, exchanges gases between the outside air and the alveoli of the lungs. Ventilation, which is mechanical in nature, depends on a difference between the atmospheric air pressure and the pressure in the alveoli. When we expand the lungs to inhale, we increase internal volume and reduce internal pressure. Lung expansion is brought about by two important muscles, the…
The respiratory system is open to airborne microbes and to outside pollution. It is not surprising that respiratory diseases occur, in spite of the body's defenses. Some respiratory disorders are relatively mild and, unfortunately, very familiar. We all experience the excess mucus, coughing, and sneezing of the common cold from time to time. The common cold is an example of rhinitis, an inf…
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User Comments
5 months ago
SAFA
WELL
11 months ago
ciao!
over 3 years ago
What happens when the earthworm's moist skin dries out? How does it lose its ability to breathe?
almost 4 years ago
Which respiratory systems of different animals are closely associated with blood supply?
almost 5 years ago
You should add more on earthworm respiration and earthworms in general.