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Gas Exchange Part 1 Begins Tell me how I’m supposed to breathe with no air? Got me out here in the water so deep Tell me how you gon be without me? If you ain’t here I just can’t breathe There’s no air no air You get the idea. Hi, I’m Mr. Lung and I’m here to present the gas exchange system. Of course, I’m not the only method of exchanging gases, but for our singers and you too I perform a very vital function. Just think; How long can you survive without oxygen? Can you hold your breath even for a minute? Now consider how important I am to you, given that I am the organ responsible for getting that oxygen to your cells and removing the waste carbon dioxide. You are probably wondering what happens to the oxygen. CELLULAR RESPIRATION is the process that actually requires the oxygen and uses it to release the energy in foods as ATP. The waste gas produced as a result of the energy release is carbon dioxide. Thus carbon dioxide is released by cells as a waste gas. Oxygen in Carbon dioxide out In order to conduct gas exchange, three criteria have to be met The membrane must: be thin have a large surface area. be moist. Different organisms use different methods to accomplish gas exchange. Differences in RESPIRATORY MEDIUM (the source of O2) make certain structures more efficient. Hi I’m Mr. Amoeba. I’m a protist and I do not have any specialized gas exchange structures, I just use diffusion. I live in water so my membrane is moist to allow for gas exchange and I am a single celled so I have a large surface area to volume ratio with only the thin plasma membrane forming the barrier. My fellow protists conduct gas exchange like I do but I also have some friends that exchange using only diffusion also ........ flatworm Phylum platyhelminthes sponges Phylum Porifera jellyfish hydra Phylum cnideria coral In aquatic environments, gills are useful for gas exchange. Here are some examples of organisms that are classified as having gills you may not be aware of. Watch this Spongebob episode for some fun. I have no nose, thus no smell. I breath through projections in my skin Sea star Phylum echinodermata Papullea are tubular projections of the skin that conduct gas exchange (gills) Scallop Marine worm Phylum annelid Class polychaetes Parapodia (used for gas exchange) are the projections you can see sticking out of the sides of the segmented worm (gills) Phylum mollusca Class bivalia Scallop gills long projecting plates with cilia that circulate the water. Crayfish Phylum arthopods Class crustacea Feathery gills covered by carapace (exoskeleton) Structures drive water over the gills Since levels of O2 are low in water, ventilation is necessary. VENTILATION? What is ventilation Mr. Lungs? Ventilation is increasing the respiratory medium over the respiratory surface. Speak English Mr. Lungs. Oh yes. I knew that Mr. Lungs. It means that pushing water over your gulls increases the amount of O2 and CO2 you can exchange through the gills. Mr. Crabs pushes water over his gills by using special paddle-like structures. Water contains less than 1% oxygen (4-8 ml dissolved oxygen per liter) and there is even less in warmer water or saltier water. This makes ventilation necessary to move water over the gill surface. Crabs spend considerable energy paddling water across their gills. In order to ventilate my gills with water, I gulp water, close my mouth and push the water over my gills, My operculum opens to allow the water out. I’m a shark and I can’t ventilate my gills the same as the other fish. I have no operculum , cannot gulp water and must constantly swim to push water across my gills (RAM VENTILATION). NEWSFLASH VIRGIN SHARKS GIVE BIRHT TO YOUNG (PARTHENOGENESIS) Recent studies have shown that female sharks are capable of asexual reproduction! Mammals, now the only group not capable of asexual reproduction. DID YOU KNOW? Hey, that’s my purse. The mermaid’s purse is an empty egg case of the shark pups. So how come a fish out of water cannot get oxygen. After all, air has 21% oxygen compared to less than 1% in water. Surely the gill should work in air given the vastly greater oxygen. Once the gills are out of water, the filaments collapse. This dramatically decreases the surface area for gas exchange. Normally water suspends the filaments. In addition, the membrane moisture must be maintained in order to exchange gases, and gills dry out quickly. Fish suffocate in air. THE COUNTERCURRENT EXCHANGE SYSTEM OF FISH Lowest oxygen 40% 25% 60% Highest oxygen level 80% 100% 45% 65% 85% Exchange ? The fish blood more effectively extracts O2 from water by maintaining the entire exchange surface with a diffusion gradient drawing O2 in. Efficiency allows absorption of more than 80% of dissolved O2 Dissolved oxygen content Front of gill Blood oxygen content Let’s get out of the water now and into a terrestrial environment. Spiders are not insects and they have book lungs often hooked together to tracheal systems. Book lung air spaces Insects use the tracheal system of gas exchange. Air moves directly into the insect body by a series of tubes called tracheae. These tubes end at terminal ends supplying virtually all body cells. The terminal ends have a moist respiratory lining that allows for gas exchange. The openings to the tubes are called spiracles. You think you can stop me by plugging my nose and mouth?. I don’t have a nose and my mouth is strictly for digestion. You are a fool to think my gas exchange is conducted by structures on my face!! Uh oh! Hopper, we do know an effective way of destroying your ability to exchange gases. You see, we have some soapy water spray that if we apply it to your body will coat your spiracles and trachea with a thin layer bubble that will restrict the passage of gases to your body cells. Works on all insects and spiders!! Insects can increase the efficiency of their tracheal gas exchange system by ventilating with body contractions. Some flying insects, ventilate with each wing movement, like a bellows action. They also have muscles very rich in mitochondria to keep up with the rapid use of oxygen with this high metabolic rate. Bees beat their wings approximately 200 times a second, which is 10–20 times as fast as nerve impulses can fire. They achieve this because their thorax muscles Myth – according to aerodynamic laws, do not expand and contract on each nerve firing, but rather vibrate like a plucked the bumblebee should not be able to rubber band. The buzz sound is made by fly. It succeeds “by the power of its own ignorance.”This does not consider the muscles, not the wings and can be dynamic stall and the vortex created heard without wing movement when generating several times normal lift. decoupled as bees warm themselves up to Errors is probably due to application a higher body temperature before flight. only of simplified oscillating aerofoils. And now it’s time to talk about lungs. The lungfish has lungs capable of sustaining it on land(especially mud) and lobed fins capable of moving it across seasonal water holes. The lungs are very primitive, like hollow balloons. The amphibians have lungs but they are small and do not provide a large surface area. They rely on diffusion across body surfaces for much of their gas exchange. They ventilate with positive pressure, pushing air that is gulped into their lungs. This is accomplished by inflating the mouth cavity, then raising the floor of the mouth to force the air into the lungs. NOTE Diaphragm not involved Reptiles (with some exceptions) birds and mammals rely exclusively on the lungs to conduct gas exchange. The lungs are restricted to one location –the circulatory system connects them to supply the body with oxygen. Sorry, but I’m an exception. I use my epithelial linings to enhance gas exchange. Someone always has to spoil the party. Well I can tell you I have lungs and I love them. I love getting the infusion of 21 % atmospheric oxygen into my body and moving around with high metabolism. Gas Exchange Part 1 Ends