Fundamental of Biology : Respiration in Vertebrate Animals Vertebrate animals have a circulation system whose function is, among other things, to transport respiratory gas (O2) from the place where the gas is caught to the tissue cells. Vice versa, to transport waste gas (CO2) from tissue cells to the place where it is excreted. Respiratory mechanisms in vertebrates vary. Read the explanation below so that you can better understand the respiratory mechanisms of vertebrates. a. Pisces Fish breathe using gills. The gills are thin, pink sheets and are always moist. The outer part of the gills is connected to water, while the inner part is closely connected to blood capillaries. Each gill sheet consists of a pair of filaments and each filament contains many thin layers (lamellae). In the filaments there are blood vessels that have many capillaries, allowing O2 to diffuse in and CO2 to diffuse out.In bony fish (Osteichthyes) the gills are equipped with gill covers (operculum), while in cartilaginous fish (Chondrichthyes) the gills do not have gill covers. Apart from breathing with gills, there is also a group of fish that breathe with air bubbles (pulmosis), namely lung fish (Dipnoi). Gills not only function as a respiratory tool, but also function as a tool for excreting salts, food filters, ion exchange tools, and osmoregulators. 1) Respiration in bony fish. One example of a bony fish is the goldfish. The gills of goldfish are stored in the gill cavity which is protected by the gill cover (operculum. The gills of goldfish consist of gill arches which are composed of white cartilage, gill ridges which function to filter respiratory water through the gills, and filaments or gill sheets. The gill filaments are composed of soft tissue, comb-shaped and pink because they have many blood capillaries and are branches of the gill arteries. This is where the exchange of CO2 and O2 gases takes place. O2 gas is taken from O2 gas dissolved in water through the gills by diffusion. From the gills, O2 is transported by the blood through the blood vessels to all body tissues.From body tissues, CO2 gas is transported by the blood to the heart. From the heart to the gills for gas exchange. This process occurs continuously and repeatedly.The breathing mechanism of bony fish is carried out through the mechanism of inspiration and expiration. a) Inspiratory phase Movement of the gill cover to the side and the membrane of the gill cover remaining attached to the body results in the oral cavity getting bigger, whereas the gap behind the gills is closed.As a result, the air pressure in the oral cavity is less than the air pressure outside. The mouth gap opens so that water flows into the oral cavity. Look at the picture on the side. b) Expiratory phase After water enters the oral cavity, the oral cavity closes. The gills return to their original position followed by the opening of the gill slits. Water in the mouth flows through the gill slits and touches the gill sheets. In this place, breathing air exchange occurs. Blood releases CO2 into the water and binds O2 from the water.During the inspiration phase, O2 and water enter the gills, then O2 is bound by blood capillaries to be carried to the tissues that need it.On the other hand, in the expiratory phase, CO2 carried by the blood from the tissues flows into the gills, and from the gills is excreted out of the body. 2) Respiration in cartilaginous fish. The gills of cartilaginous fish do not have gill covers (operculum), for example in sharks. The entry and exit of air from the oral cavity is caused by changes in pressure in the oral cavity caused by changes in the volume of the oral cavity due to the up and down movement of the oral cavity. When the floor of the mouth moves downwards, the volume of the oral cavity increases, so the pressure is less than the pressure of the surrounding water.As a result, water flows into the oral cavity through the mouth gap, which ultimately occurs the process of inspiration. If the floor of the mouth moves upwards, the volume of the oral cavity decreases, the pressure increases, the mouth gap closes, so that water flows out through the gill slits and CO2 exhalation occurs. At this time, O2 and CO2 gas exchange occurs . 3) Respiration in lungfish (Dipnoi) Lungfish breathing resembles the breathing of Amphibia. Apart from having gills, lungfish have one or a pair of air bubbles like lungs which can be used to aid breathing, namely pulmosis. Pulmosis is surrounded by many blood vessels and is connected to the esophagus by the pneumatic duct. This channel is the way for air to enter and exit from the mouth to the bubble and vice versa, while also allowing air to diffuse into the blood capillaries.Lungfish live in swamps and rivers.This fish is able to survive even though the water is dry and its gills are not functioning, because it breathes using air bubbles. There are three types of lungfish in the world, namely African lungfish, South American lungfish, and Queensland lungfish (Australia). Some types of fish, such as catfish, snakeheads, gourami and betok, have a breathing apparatus called a labyrinth. The labyrinth is an upward expansion in the gill cavity, and forms folds so that it forms irregular cavities. The function of the labyrinth cavity is to store air (O2), so that the fish can survive in waters with low oxygen content. Apart from the labyrinth, air (O2) is also stored in the swim bladder which is located near the back. b. Amphibia Young frogs (tadpoles) use gills to take in O2 dissolved in water. After approximately 12 days of age, the external gills are replaced with internal gills.As adults, frogs breathe using the membranes of the oral cavity, lungs and skin.The lining of the oral cavity can function as a respiratory tool because it is thin and there are many capillaries that open there. When the oral cavity and pharynx move, the nostrils open and the glottis closes, so that air is in the oral cavity and diffuses in through the thin oral membrane. Breathing with the skin is carried out by diffusion. This is because frog skin is thin, always moist, and contains many blood capillaries. Skin breathing takes place effectively both in water and on land. Oxygen (O2) that enters through the skin will be transported through the skin veins of the lungs (vena pulmo cutanea) to the heart to be distributed throughout the body. On the other hand, carbon dioxide (CO2) from the tissues will be brought to the heart, from the heart it is pumped to the skin and lungs via the pulmonary skin artery (pulmo cutanea artery). Thus, the exchange of oxygen and carbon dioxide occurs in the skin. Frogs also breathe with lungs, but not as well as mammals' lungs. Frog lungs are a pair of thin, elastic sacs so that breathing air can diffuse, and the walls are surrounded by many blood capillaries so that the frog's lungs are reddish in color. The lungs and the oral cavity are connected by short bronchi. As in fish, breathing in frogs includes the process of inspiration and expiration which takes place when the mouth is closed. This breathing mechanism is regulated by the respiratory muscles, namely: the lower jaw muscles (submandibularis), sternohioideus, geniohyoideus, and abdominal muscles. The mechanism of inspiration and expiration is explained as follows. 1) Inspiratory phase The inspiratory phase occurs when the sternohyoid muscle contracts so that the oral cavity expands, resulting in oxygen entering through the choane (nose gap). After that, the choane closes, the submandibular and geniohyoid muscles contract, so that the oral cavity shrinks. The shrinking of the oral cavity forces oxygen to enter the lungs through the gaps. In the lungs, gas exchange occurs, oxygen is bound by the blood in the capillaries of the lung walls, and conversely carbon dioxide is released into the environment. 2) Expiratory phase The expiratory mechanism occurs after gas exchange in the lungs, the lower jaw muscles relax or relax, while the abdominal and sternohioideus muscles contract. This causes the lungs to shrink, so that air is forced out and into the oral cavity. Next, the choane opens, while the throat gap closes, resulting in contraction of the lower jaw muscles followed by contraction of the geniohyoid muscles.As a result, the oral cavity shrinks and air rich in carbon dioxide is pushed out through the choane. c. Reptiles The lungs of reptiles are located in the chest cavity and are protected by the rib cage. Reptile lungs only consist of several folds of walls which function to increase the surface for gas exchange. The lungs of lizards, turtles, and crocodiles are more complex, with several divisions that give the lungs a spongy texture. The lungs of some types of lizards, for example the African chameleon, have air sacs or reserve air sacs that allow the animal to float in the air.Reptiles breathe using lungs. O2 gas in the air enters through the nostrils, the oral cavity, the pharynx, the long trachea, the bronchioles in the lungs. From the lungs, O2 is transported by the blood to all body tissues. From the body's tissues, CO2 gas is transported by the blood to the heart to be expelled through the lungs, bronchioles, long trachea, pharynx, oral cavity, nostrils. In reptiles that live in water, the nostrils can be closed when diving. d. Aves In birds, the place where breathing air diffuses occurs in the lungs. Bird lungs are a pair and are located in the chest cavity which is protected by the ribs.The respiratory tract (air entry into the body) in birds is as follows. 1) Two pairs of nostrils located at the base of the upper beak and on the roof of the oral cavity. 2) The throat gap which is found at the base of the esophagus or pharynx which connects the oral cavity to the trachea. 3) The trachea or windpipe is long, pipe-shaped, and supported by rings of cartilage. 4) A pair of pink lungs located in the chest cavity. This section includes the right bronchus and left bronchus which are the final branches of the trachea. In the bronchi at the base of the trachea, there are syringes (syringes), which inside there are folds in the form of membranes that can vibrate and can make sounds. The bronchi branch again into mesobronchi, which are secondary bronchi, and can be divided into ventrobronchi (ventral part) and dorsobronkus (dorsal part). The ventrobronchi are connected to the dorsobronchi by many parabronchi (100 or more).The parabronchi are small tubes. In parabronkus boils down to a lot of capillaries that allow air to diffuse.part from the lungs, birds usually have 4 pairs of lung extensions called air bladders or air sacs (saccus pneumaticus) which spread to the stomach, neck and wings. These air sacs are found at the base of the neck (saccus cervicalis), the chest cavity (saccus thoracalis anterior and posterior), between the collarbones or coracoids (saccus interclavicularis), the armpits (saccus axillaris), and between the folds of the intestine or abdominal cavity (saccus abdominalis). The air sacs are connected to the lungs, have a thin membrane, but there is no diffusion of respiratory air. The presence of air sacs results in efficient breathing in birds. Airbags have the following functions. 1) Helps breathing, especially when flying, because it stores oxygen reserves. 2) Helps maintain body temperature by preventing excessive loss of body heat. 3) Helps amplify the sound by enlarging the sound chamber. 4) Regulating the specific gravity (lightening) of the body when the bird flies. The respiratory mechanism in birds is divided into two, namely breathing when resting and breathing when flying.When resting, the ribs move forward, the chest cavity enlarges, the lungs expand so that air enters and flows through the bronchi to the rear air sacs, at the same time the air that is already in the rear air sacs flows into the lungs and into the sacs. front air. When the ribs return to their original position, the chest cavity shrinks so that air from the air sacs enters the lungs. Furthermore, when in the alveolus, O2 is bound by alveolar capillary blood. So, binding of O2 takes place during inspiration and expiration. When flying, inspiration and expiration are carried out by air sacs. When the wings are raised upwards, the air sacs in the armpits expand, while the air sacs in the coracoid bone are squeezed, resulting in inspiration (O2 at that location enters the lungs). When the wings are lowered, the air sacs in the armpit are squeezed, while the air sacs in the coracoid bone expand, so that expiration occurs (O2 in that place comes out). The higher a bird flies, the faster it flaps its wings to get enough oxygen.Of the outside air that enters, a small portion remains in the lungs, and the majority will be passed to the air sacs as reserve air. The air in the air sacs is used only when the air (O2) in the lungs is low, namely when the bird is flapping its wings. e. Mammalia Mammals breathe using lungs. O2 gas enters the body through the nostrils, pharynx, larynx, trachea, bronchus, lungs. Then O2 gas from the lungs is transported by the blood to the heart. From the heart, O2 gas is circulated to all body tissues by the blood. From body tissues, CO2 gas is transported to the heart ÿ lungs, and out through the same organs.