... trachea is a pipe shaped by rings of cartilage. It divides into two tubes called bronchi. These carry air into each lung. Inside the lung, the tubes divide into smaller and smaller tubes called bronchioles. At the end of each of these tubes are small air sacs called alveoli. Capillaries, which are small blood vessels with thin walls, are wrapped around these alveoli. The walls are so ... thin and close to each other that the air easily seeps through. In this way, oxygen seeps through into the bloodstream and carbon dioxide, in the bloodstream, seeps through ... into the alveoli, and is...

• Word Count: 876
• Approx Pages: 4
• Grade Level: High School

... carbon dioxide. The concentrations of these gases, while small, varied widely from place to place. In fact, atmospheric gases are often divided up into the major, constant components and the highly variable components, as shown in Table 1 and Table 2. Table 1: Constant Components. Proportions remain the same ... atmosphere: nitrogen (78%), and oxygen (21%). Argon, carbon dioxide and various trace gases make up the remainder. Scientists divided the atmosphere into four layers according to temperature: troposphere, stratosphere, mesosphere, and thermosphere. The temperature drops as we go...

• Word Count: 3528
• Approx Pages: 14
• Grade Level: High School

... in danger of becoming sterile, which would put the species at risk of becoming extinct. As with sulphur dioxide in rain, mercury is also discharged into the water. There is a direct connection between the mercury rich lakes as there is with those with high acidic levels. This metal becomes concentrated ... for respiratory disease and crop damage. The photochemical smog is also causing the ozone layer to disintegrate. An inordinate amount of sulphur dioxide is let into the air, more than can be neutralized by natural nutrients. The ecosystem is slowly eroding due to the increased amounts ...

• Word Count: 676
• Approx Pages: 3
• Grade Level: High School

... is a "noctilucent" cloud that has formed because of buildup of methane gas in the atmosphere. This excess methane gas carries more water vapor into the atmosphere and condenses at much higher altitudes than the sun will strike. It is important to realize that environmental issues should be considered a ... goes on forever and cannot be filled. The truth is completely opposite. The pictures brought back by astronauts show the atmosphere as a very thin translucent blanket covering the planet. "The distance from the ground to the top of the sky is no farther than an hours cross-country ....

• Word Count: 1670
• Approx Pages: 7
• Grade Level: High School

... over the gill surfaces Gills are highly efficient gas exchange organs The filaments of gills are made up of thin disklike structures lined up parallel with the direction of water movement 21.2 Gas Exchange in Terrestrial Organisms When organisms moved onto land, air became the source of their ocygen Water is relatively poor in oxygen It contains only about 5 to 10 ... throughout the body In many vertebrates, lungs are the organs of gas exchange Among mammals, including humans, air is taken into and forced out of the lungs through the actions of two groups of muscles, the diaphragm and t...

• Word Count: 1295
• Approx Pages: 5

... cover the tundra, and cacti dot the desert? • Trees turn carbon dioxide into oxygen that helps us breathe and reduces air pollution. • Trees also filter lots of other chemicals from our air and purify it making the air healthier for us to breathe. • They also provide shelter from the sun ... is sufficiently abundant - without being too abundant. Before the evolution of the plants that make up today's forests, more primitive species still shaped themselves into tree-like forms--like giant club mosses (today appearing as runners a few inches above the ground), tree ferns, and cycads (...

• Word Count: 2774
• Approx Pages: 11
• Grade Level: High School

... , lungs, and diaphragm are all factors in which respiration is taking place. (As shown in picture e) we have a clear passageway for air, from outside into our mouth, to our pharynx, trachea, bronchi, bronchioles, and the alveoli. We have to get the air into our alveoli, because that is where all gas exchange with oxygen and carbon dioxide will occur. All of the above are ... small sacs called alveoli. Alveoli, is what is at the end of the bronchioles. They are air sacs and that are arraigned sort of like grapes on a stem. Our bodies contain over 500 air filled sac that are the capillarie...

• Word Count: 356
• Approx Pages: 1
• Grade Level: High School

... as is nitrogen, in fertilizers. Carbon is an essential element in all living organisms. The carbon cycle is the transferring of carbon dioxide (CO2) into the air or water by plants through photosynthesis (solar energy). A carbon atom makes this journey about once every three years. Carbon can be transferred from plants ... to algae, to shellfish to animals that feed on the shellfish and respired back into the air as CO2. It can also be released into the atmosphere by combustion of fossil fuels. It takes millions of years for carbon to come from sediment of algae ... used in its natural...

• Word Count: 1039
• Approx Pages: 4
• Grade Level: High School

... as is nitrogen, in fertilizers. Carbon is an essential element in all living organisms. The carbon cycle is the transferring of carbon dioxide (CO2) into the air or water by plants through photosynthesis (solar energy). A carbon atom makes this journey about once every three years. Carbon can be transferred from plants ... to algae, to shellfish to animals that feed on the shellfish and respired back into the air as CO2. It can also be released into the atmosphere by combustion of fossil fuels. It takes millions of years for carbon to come from sediment of algae ... used in its natural...

• Word Count: 1044
• Approx Pages: 4
• Grade Level: High School

... regions. Acid rain can harm both the land and the water. It is most damaging when it falls in streams, lakes, and on thin, sandy soil low in calcium carbonate (lime). Lime neutralizes the effects of the acid. Aside from polluting topsoil acid rain can alter entire ecosystems ... is formed when the byproducts of fossil fuels production combine with atmospheric water. Smoke expelled from smokestacks that reach a thousand feet into the air are saturated with sulfur dioxide, nitrogen dioxide and other chemicals. Wind carries the smoke hundreds of mile away from where it is generated. ... fr...

• Word Count: 683
• Approx Pages: 3
• Grade Level: High School

... about the heart pumping blood around the body. The Respiratory System is the system in which delivers oxygen from the air to our blood system and then return as waste products back outside into the air. In order for our bodies to carry out any form of exercise, the cells in our body need oxygen. ... -respiratory system works you need to understand how, first of all, the heart works. Diagram of the heart As you can see the heart is split into four different chambers, the right atria, right ventricle, the left atria, and the left ventricle. Deoxygenated blood enters the right atria through ...

• Word Count: 655
• Approx Pages: 3

... where carbon dioxide is released to be expelled from the body. The transfer of these two gasses takes place in the alveoli in the lungs. "Alveoli are "small cavities" or "air sacs in the lungs" ( Marieb G-2). Blood entering the lungs through the pulmonary circulation is dark colored, low in oxygen, and high in carbon dioxide. The blood is pumped by the ... of cavities in the lungs. The lungs are designed to receive air, which enters the body through the nose and mouth. The air passes through the pharynx and the larynx and enters the airways, beginning with the trachea and then into two ...

• Word Count: 936
• Approx Pages: 4
• Grade Level: High School

... Automobiles are the main source of nitrogen oxide emissions, and utility factories are the main source for sulfur dioxide emissions. These gases evaporate into the atmosphere and then oxidized in clouds to form nitric or nitrous acid and sulfuric acid. Acid rain kills plant life and destroys ... and roads"(EPA). Then while flowing to streams, lakes, and marshes acid rain releases aluminum, which is highly toxic to many species of aquatic organisms, into the water ways. This raises the acidic level of lakes and streams. According to Environmental Issues "Most lakes and streams have a ph b...

• Word Count: 1178
• Approx Pages: 5
• Grade Level: High School

... are ones that experience intense drought or extreme cold. Desert animals cope with heat and water shortage by remaining below ground by day. In tundra and on polar ice, winter air temperatures can fall to below -40 C (-40 F). The few animals that do remain active on land or ice during winter, such as seals and male emperor penguins, rely on ... numbers of spores. A giant puffball, for example, produces an estimated 7 trillion spores. Classification: primarily the type of spores and fruiting bodies produced classifies Fungi. The Fungi Kingdom can be divided into four main categories: Chyt...

• Word Count: 2632
• Approx Pages: 11

... Rocky Mountains, are already constrained by climate, and are likely to face extreme stress and disappear entirely in some places. Global warming suggests the potential for forests to break up into an assortment of forests, savannas, and grasslands. Major adjustments to natural ecosystems due to climate change could have negative consequences for our economy, which depends in part on the ... return to the atmosphere. Trees also have a crucial role in the oxygen cycle: they make up an essential part of one of the world's life support systems. Agricultural expansion into forestland is the ...

• Word Count: 700
• Approx Pages: 3
• Grade Level: Undergraduate