Sunday, July 27, 2008
Entry 18: Reflections of Biology Journal
Althought this will be my last post on this blog for my Biology Journal Blog Project, I am not exactly feeling very happy that I do not have to update the blog anymore as have found it a very pleasant learning experience. Initially, when I was told by my Chemistry teacher, Ms Qiu to do 3 entries per week on two topics on this blog over a period of six weeks, I felt apprehensive and was not willing to spend my internet time on Biology. Well, it was my first research post that made me change my mind. I had discovered it was quite fun after all, searching all over the internet for relevant information, and compiling them together like book. I had copied plenty of the information from several websites and hope the owners would not mind as I have left the URL's of sites which I have copied the information from. I think that's about all I have to say, and my conclusion is that this Biology Journal has really helped me in understanding Digestion,Ecology and Nutrient Cycles, with the aid of the many Biology sites I have visited.
Entry 17: Human Aspect of Nutrient Cycles
As I had mentioned in my last post, this shall be my last informative post before I start on my reflections of this Biology Online-Blog Journal in general. There is no doubt, that humans rely directly and indirectly on nature for their survival and that humans are taking a toll on the environment in which they live. The majority of, the world's population receives its food supply from sustainable agriculture practices, which began with the selection of wild seeds several thousand years ago.
Modern agriculture has done away with the slow process of natural selection and hybridization. For this reason it is important that human kind does not allow the biodiversity of the world to slip away, since the plants we loose today could be the cure for the diseases of tomorrow. Not only do humans effect the environment through agriculture; they also rapidly transform environments into shopping malls, or housing developments, often destroying, habitat for animals. In industrialized nations petroleum products drive the economy, by fueling our cars and other modes of transportation, decayed organic material is essential to the health of the global economy, in less industrialized areas organic matter such as wood and coal are important, parts of the everyday lives of the people. It as been shown that the world cannot sustain another century like the past one with over 1,000 species going extinct for every new species which evolves. Where everything, which is consumed, is replaced, keeping an accurate balance of the diversity of life on earth will be essential to the survival of humankind.
The environment has become one of the most important issues of our time and will continue to be well into the future. The challenge is to find approaches to environmental management that give people the quality of life they seek while protecting the environmental systems that are also the foundations of our well being.
Information obtained from:
1)http://www.enviroliteracy.org/category.php/5.html
2)http://library.thinkquest.org/C007506/aspect.html
Modern agriculture has done away with the slow process of natural selection and hybridization. For this reason it is important that human kind does not allow the biodiversity of the world to slip away, since the plants we loose today could be the cure for the diseases of tomorrow. Not only do humans effect the environment through agriculture; they also rapidly transform environments into shopping malls, or housing developments, often destroying, habitat for animals. In industrialized nations petroleum products drive the economy, by fueling our cars and other modes of transportation, decayed organic material is essential to the health of the global economy, in less industrialized areas organic matter such as wood and coal are important, parts of the everyday lives of the people. It as been shown that the world cannot sustain another century like the past one with over 1,000 species going extinct for every new species which evolves. Where everything, which is consumed, is replaced, keeping an accurate balance of the diversity of life on earth will be essential to the survival of humankind.
The environment has become one of the most important issues of our time and will continue to be well into the future. The challenge is to find approaches to environmental management that give people the quality of life they seek while protecting the environmental systems that are also the foundations of our well being.
Information obtained from:
1)http://www.enviroliteracy.org/category.php/5.html
2)http://library.thinkquest.org/C007506/aspect.html
Entry 16: The Water Cycle
In my opinion, this post on Nutrient Cycles is the most interesting, and here it goes.
Earth has a stable water supply which 98 percent of the earths water is contained in, oceans, lakes, rivers and streams with the remaining found in, the form of ice, water vapor, and in the bodies of living organisms. The constant movement of water, from earth to the atmosphere is called the water cycle. This cycle is driven by solar energy, and causes Earth's water supply is used over and over again. The sun evaporates water off of water bodies such as rivers and lakes, as well as form moist surfaces and bodies of living organisms.
This water is drawn back up into the atmosphere, and falls back to earth in the form of rain. There is a greater amount of evaporation, from the ocean than the amount of precipitation (rainfall) this results in a movement of water vapor by the wind to inland areas, areas closer the ocean receive more precipitation (rainfall) than those which are further from the ocean or are protected by a mountain range. Water is also absorbed from the bodies of terrestrial plants and animals as well as the soil, the collective process of evaporation from the soil and plants is called evapotransporation. This constant movement of water through evaporation by the sun. Water which is not evaporated by the sun may reenter the water cycle by seeping down through the soil, until it reaches the, a zone of saturation, here all of the holes and cracks of the soil are filled with water below which there is a bed of solid rock which the water cannot penetrate.
In my next post, which should also be my last informative post, I shall be continuing on the human aspect of nutrient cycles and finally my reflections of the whole Biology Learning Journal.
Information obtained from:
1)http://library.thinkquest.org/C007506/cycles.html
Earth has a stable water supply which 98 percent of the earths water is contained in, oceans, lakes, rivers and streams with the remaining found in, the form of ice, water vapor, and in the bodies of living organisms. The constant movement of water, from earth to the atmosphere is called the water cycle. This cycle is driven by solar energy, and causes Earth's water supply is used over and over again. The sun evaporates water off of water bodies such as rivers and lakes, as well as form moist surfaces and bodies of living organisms.
This water is drawn back up into the atmosphere, and falls back to earth in the form of rain. There is a greater amount of evaporation, from the ocean than the amount of precipitation (rainfall) this results in a movement of water vapor by the wind to inland areas, areas closer the ocean receive more precipitation (rainfall) than those which are further from the ocean or are protected by a mountain range. Water is also absorbed from the bodies of terrestrial plants and animals as well as the soil, the collective process of evaporation from the soil and plants is called evapotransporation. This constant movement of water through evaporation by the sun. Water which is not evaporated by the sun may reenter the water cycle by seeping down through the soil, until it reaches the, a zone of saturation, here all of the holes and cracks of the soil are filled with water below which there is a bed of solid rock which the water cannot penetrate.
In my next post, which should also be my last informative post, I shall be continuing on the human aspect of nutrient cycles and finally my reflections of the whole Biology Learning Journal.
Information obtained from:
1)http://library.thinkquest.org/C007506/cycles.html
Entry 15: Nutrient/Biogeochemical Cycles 2
Well, I hope you have a undersatnding of Nutrient cycles already, if you have not, please read the last post. The content may seem quite difficult to understand initially, as I copied most information from websites and put them here without rephrasing as it's really difficult to rephrase certain parts. I hope you undersatnd, Ms Qiu. Read slowly, and you should be able to get it though.
Without further ado...Many elements cycle through ecosystems, organisms, air, water, and soil. Many of these are trace elements. Other elements, including carbon, nitrogen, oxygen, hydrogen, sulfur, and phosphorus are critical components of all biological life. Together, oxygen and carbon account for 80 percent of the weight of human beings. Because these elements are key components of life, they must be available for biological processes. Carbon, however, is relatively rare in the Earth's crust, and nitrogen, though abundant in the atmosphere, is in a form that is not useable by living organisms. The biogeochemical cycles transport and store these important elements so that they can be used by living organisms. Each cycle takes many different pathways and has various reservoirs, or storage places, where elements may reside for short or long periods of time. Each of the chemical, biological, and geological processes varies in their rates of cycling. Some molecules may cycle very quickly depending on the pathway. Carbon atoms in deep ocean sediments may take hundreds to millions of years to cycle completely through the system. An average water molecule resides in the atmosphere for about ten days, although it may be transported many miles before it falls back to the Earth as rain. I shall elaborate on the water cycle in my next post, do read on.
Informatrion obtained from:
1)http://www.enviroliteracy.org/subcategory.php/198.html
2)http://library.thinkquest.org/C007506/cycles.html
Without further ado...Many elements cycle through ecosystems, organisms, air, water, and soil. Many of these are trace elements. Other elements, including carbon, nitrogen, oxygen, hydrogen, sulfur, and phosphorus are critical components of all biological life. Together, oxygen and carbon account for 80 percent of the weight of human beings. Because these elements are key components of life, they must be available for biological processes. Carbon, however, is relatively rare in the Earth's crust, and nitrogen, though abundant in the atmosphere, is in a form that is not useable by living organisms. The biogeochemical cycles transport and store these important elements so that they can be used by living organisms. Each cycle takes many different pathways and has various reservoirs, or storage places, where elements may reside for short or long periods of time. Each of the chemical, biological, and geological processes varies in their rates of cycling. Some molecules may cycle very quickly depending on the pathway. Carbon atoms in deep ocean sediments may take hundreds to millions of years to cycle completely through the system. An average water molecule resides in the atmosphere for about ten days, although it may be transported many miles before it falls back to the Earth as rain. I shall elaborate on the water cycle in my next post, do read on.
Informatrion obtained from:
1)http://www.enviroliteracy.org/subcategory.php/198.html
2)http://library.thinkquest.org/C007506/cycles.html
Entry 14: Nutrient/Biogeochemical Cycles 1
Assuming you already know what is an ecosystem from Entry 8, I shall not bother explaining it as I continue on nutrient cycles(also known as biogeochemical cycles). Life on earth is inextricably linked to climate through a variety of interacting cycles and feedback loops. In recent years there has been a growing awareness of the extent to which human activities, such as deforestation and fossil fuel burning, have directly or indirectly modified the biogeochemical and physical processes involved in determining the earth's climate. These changes in atmospheric processes can disturb a variety of the ecosystem services that humanity depends upon.
The Earth is a closed system for matter, except for small amounts of cosmic debris that enter the Earth's atmosphere. This means that all the elements needed for the structure and chemical processes of life come from the elements that were present in the Earth's crust when it was formed billions of years ago. This matter, the building blocks of life, continually cycle through Earth's systems, the atmosphere, hydrosphere, biosphere, and lithosphere, on time scales that range from a few days to millions of years. These cycles are called biogeochemical cycles, because they include a variety of biological, geological, and chemical processes. In my next post, I shall be going in-depth about nutrient/biogeochemical cycles, and hope to give you a better understanding.
Information obtained from:
1)http://essp.csumb.edu/esse/climate/climatebiogeo.html
2)http://www.enviroliteracy.org/subcategory.php/198.html
The Earth is a closed system for matter, except for small amounts of cosmic debris that enter the Earth's atmosphere. This means that all the elements needed for the structure and chemical processes of life come from the elements that were present in the Earth's crust when it was formed billions of years ago. This matter, the building blocks of life, continually cycle through Earth's systems, the atmosphere, hydrosphere, biosphere, and lithosphere, on time scales that range from a few days to millions of years. These cycles are called biogeochemical cycles, because they include a variety of biological, geological, and chemical processes. In my next post, I shall be going in-depth about nutrient/biogeochemical cycles, and hope to give you a better understanding.
Information obtained from:
1)http://essp.csumb.edu/esse/climate/climatebiogeo.html
2)http://www.enviroliteracy.org/subcategory.php/198.html
Entry 13:Environmental Protection 2
As mentioned in my previous entry, I'll be continuing on reusing and recycling today. Apart from reducing electricity usage and gas emissions, you can help reduce pollution just by putting that soda can in a different bin. If you're trying to choose between two products, pick the one with the least packaging. If an office building of 7,000 workers recycled all of its office paper waste for a year, it would be the equivalent of taking almost 400 cars off the road! If you must drink bottled water or can drinks, put them in the recycling bin, which helps to reduce the amount of space taken up at landfills by solid waste. By reusing paper bags and everyday waste like cardboard boxes, why not reuse them? You do not waste money on unnecessary boxes and bags by reusing whatever you have instead of conveniently dumping them away. This will go a long way in environmental protection and make a earth an even cleaner place for generations to come.
By following these tips, you can help to save precious money and do your part in saving the earth. Remember, REUSE, REUCE and RECYCLE!
Information obtained from:
1)http://www.environmental-protection.org.uk/transport/car-pollution/#wa638
2)http://interiordec.about.com/library/weekly/aa042201a.htm
3)http://science.howstuffworks.com/save-earth-top-ten.htm
By following these tips, you can help to save precious money and do your part in saving the earth. Remember, REUSE, REUCE and RECYCLE!
Information obtained from:
1)http://www.environmental-protection.org.uk/transport/car-pollution/#wa638
2)http://interiordec.about.com/library/weekly/aa042201a.htm
3)http://science.howstuffworks.com/save-earth-top-ten.htm
Entry 12:Environmental Protection 1
Today's topic shall be on Environmental protection, and how you can do your part in saving the earth. Environmental protection or going green, is actually easier than you think. There a a few things you can do which can help to make a less harmful impact on the environment. Help to save the Earth by reusing, recycling and reducing. In this post I shall only be touching on reducing usage of cars and savng electricity, as it's fairly long alone. Firstly, when you reduce your usage of cars, you save money and the planet. You can stop using the car for short journeys and switch to public transportation instead. If you just stay off the road twice weekly, you'll reduce greenhouse gas emissions by an average of 1590 pounds per year. Alternatively, you can walk or cycle for short distances. It not only saves money spent on fuel, you burn calories and improve your health too! Also, to save electricity, which in turn saves the earth, you should use compact fluorescent which only use 1/4 the amount of electricity and incandescent one uses while generating the same amount of light. In my next post I'll be giving you more helpful tips on reusing and recycling, so do continue reading!
Information obtained from:
1)http://www.environmental-protection.org.uk/transport/car-pollution/#wa638
2)http://interiordec.about.com/library/weekly/aa042201a.htm
3)http://science.howstuffworks.com/save-earth-top-ten.htm
Information obtained from:
1)http://www.environmental-protection.org.uk/transport/car-pollution/#wa638
2)http://interiordec.about.com/library/weekly/aa042201a.htm
3)http://science.howstuffworks.com/save-earth-top-ten.htm
Saturday, July 26, 2008
Entry 11:Sources of Global Warming
I shall start an in-depth study of the burning question in my mind for so long, Who exactly is responsible for global warming and pollution? What do they do to the environment? Well actually, we humans are responsible for this mess we created. World wide emissions are increasingly rapidly due to the modernisation of society, and can accomodate power plants, transportation, oil refining, burning and depletion of Earth's resources and waste deposition. Waste deposition releases methane, which also enhances the greenhouse effect. Everyday emissions from factories and cars are some of the worse causes of pollution and ozone depletion. Fossil fuel combustion, particularly as it occurs in motor vehicles, has been identified as the largest contributor to air pollution in the world. Motor-driven vehicles do have a big impact on us and our environment, and most of us would probably not be able to live life so comfortably without efficient transportation. Not all pollution produced by cars is the same. In fact, there are two types of pollution discharged by petrol vehicles.
Information obtained from:
1)http://www.epa.vic.gov.au/air/aq4kids/cars.asp
2)Sec 2 "Project Work 2008" (Group Powerpoint slides)
- Exhaust emissions: including dangerous gases such as carbon monoxide, oxides of nitrogen, hydrocarbons and particulates.
- Evaporative emissions: vapours of fuel which are released into the atmosphere, without being burnt.
Information obtained from:
1)http://www.epa.vic.gov.au/air/aq4kids/cars.asp
2)Sec 2 "Project Work 2008" (Group Powerpoint slides)
Entry 10:Consequences of Global Warming
I'll be touching on the consequences of global warming now that you understand what it's about. You may be thinking right now, "I know what is global warming but I do not have to care about it since it does not affect me." Well, I am sorry, but you are most definitely wrong. Yes, it is not affecting you now, but the condition is worsening, and it could harm our planet in the next few years to come. With more air pollution, more and more people could contract respiratory dieseases worldwide, which can severely impact our breathing! For example, bronchitis could affect our respiratory system, and though rare among us today, it could possibly be a common illness in future.
With air pollution, we can expect more babies to be bron with chronic asthma. This illness has no cure and we would have to carry inhalers everywhere we go, and if you happen to forget to use it, you would experience shortness of breath. The worse case scenario would be that Earth would be too unhealthy to be inhabitable. To add to the large percentage of greenhouse gases in the atmosphere, loggers continue to destroy nature's precious habitat- the forests. I fthis goes on, we would not have enough trees to provide oxygen for us all. Burning the trees releases toxic fumes that are unhealthy for mankind too. These are some causes of pollution which are highly likely to occur in future, and poses a great threat to the survival of mankind.
Now that you know the causes of air pollution, I would touch on the sources of pollution and how we can reduce greenhouse gas emission and how to play our part in saving the earth! In my next post of course, so read on.
Information obtained from:
1) Sec 2 "Project Work 2008"(Group Powerpoint slides)
With air pollution, we can expect more babies to be bron with chronic asthma. This illness has no cure and we would have to carry inhalers everywhere we go, and if you happen to forget to use it, you would experience shortness of breath. The worse case scenario would be that Earth would be too unhealthy to be inhabitable. To add to the large percentage of greenhouse gases in the atmosphere, loggers continue to destroy nature's precious habitat- the forests. I fthis goes on, we would not have enough trees to provide oxygen for us all. Burning the trees releases toxic fumes that are unhealthy for mankind too. These are some causes of pollution which are highly likely to occur in future, and poses a great threat to the survival of mankind.
Now that you know the causes of air pollution, I would touch on the sources of pollution and how we can reduce greenhouse gas emission and how to play our part in saving the earth! In my next post of course, so read on.
Information obtained from:
1) Sec 2 "Project Work 2008"(Group Powerpoint slides)
Entry 9:What is Global warming?
I shall start my post on Ecology-Global Warming. The greenhouse effect has also become an increasingly hot topic in the past few years, as global temperatures are rapidly on the rise. If all of this sounds like nonsense to you, I shall explain in detail what on Earth is global warming.
Well, firstly, global warming is the increase in the average measured temperature of Earth's near-surface air and oceans since the mid-twentieth century, and its projected continuation.
Well, firstly, global warming is the increase in the average measured temperature of Earth's near-surface air and oceans since the mid-twentieth century, and its projected continuation.
The Intergovernment Panel on Climate Change (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely due to the observed increase in anthropogenic (man-made) greenhouse gas concentrations" via an enhanced greenhouse effect. These greenhouse gases trap unnecessary heat in the atmosphere, and pollution is the biggest problem. There are several forms of pollution that contribute to the emission of greenhouse gases like carbon dioxide. Although trees help to absorb carbon dioxide and give out oxygen, pollution continues and people continue destroying the environment and harming our planet. I shall continue on the consequences of global warming and how we can stop it in my next few posts. I hope you understand what is global warming now and please read on to learn more.
Information obtained from:
1)http://en.wikipedia.org/wiki/Global_Warming
Information obtained from:
1)http://en.wikipedia.org/wiki/Global_Warming
Saturday, July 19, 2008
Entry 8:What is an Ecosystem?
I have completed on my first topic and I hope you have enjoyed reading it and learnt something new. I shall be starting on my second topic, Ecology and Nutrient cycles in the Ecosystem. I do not know much about this topic, and would like to learn more about it through the Internet. I hope the information below would be useful.
Firstly, what on Earth is the Ecosystem? An ecosystem is a natural unit consisting of all plants, animals and micro-organisms (biotic factors) in an area functioning together with all the non-living physical (abiotic) factors of the environment. Ecosystems vary in size. They can be as small as a puddle or as large as earth itself. Any group of living and non-living things interacting with each other can be considered as an ecosystem. The whole Earth's surface can be described by a series of interconnected ecosystems. Within each ecosystem, there may also be habitats which vary in size. A habitat is a place in which a population lives. A population is a group of living organisms of the same kind living in the same place at the same time. All of the populations interact and form a community. The community of living organisms interact with the non-living world around it to form an ecosystem. The habitat must also be able to support the needs of organisms, such as food, water, temperature, oxygen and minerals.
I hope you have learnt more about the ecosystem, and I would continue this topic on ecology and nutrient cycles in my next post. :D
Information obtained from:
1)http://www.fi.edu/tfi/units/life/habitat/habitat.html
2)http://en.wikipedia.org/wiki/Ecosystem
3)http://www.abheritage.ca/abnature/Ecosystems/intro.htm
Firstly, what on Earth is the Ecosystem? An ecosystem is a natural unit consisting of all plants, animals and micro-organisms (biotic factors) in an area functioning together with all the non-living physical (abiotic) factors of the environment. Ecosystems vary in size. They can be as small as a puddle or as large as earth itself. Any group of living and non-living things interacting with each other can be considered as an ecosystem. The whole Earth's surface can be described by a series of interconnected ecosystems. Within each ecosystem, there may also be habitats which vary in size. A habitat is a place in which a population lives. A population is a group of living organisms of the same kind living in the same place at the same time. All of the populations interact and form a community. The community of living organisms interact with the non-living world around it to form an ecosystem. The habitat must also be able to support the needs of organisms, such as food, water, temperature, oxygen and minerals.
I hope you have learnt more about the ecosystem, and I would continue this topic on ecology and nutrient cycles in my next post. :D
Information obtained from:
1)http://www.fi.edu/tfi/units/life/habitat/habitat.html
2)http://en.wikipedia.org/wiki/Ecosystem
3)http://www.abheritage.ca/abnature/Ecosystems/intro.htm
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Monday, July 14, 2008
Entry 7:Absorption and Transport of Nutrients
I have found a good website explaining the absorption and transport of nutrients today and hence decided to post an entry on this topic, which is also linked to the intesting topic of Digestion!
Most digested molecules of food, as well as water and minerals, are absorbed through the small intestine. The mucosa of the small intestine contains many folds that are covered with tiny fingerlike projections called villi. In turn, the villi are covered with microscopic projections called microvilli. These structures create a vast surface area through which nutrients can be absorbed. Specialized cells allow absorbed materials to cross the mucosa into the blood, where they are carried off in the bloodstream to other parts of the body for storage or further chemical change. This part of the process varies with different types of nutrients.
1)Carbohydrates. The Dietary Guidelines for Americans 2005 recommend that 45 to 65 percent of total daily calories be from carbohydrates. Foods rich in carbohydrates include bread, potatoes, dried peas and beans, rice, pasta, fruits, and vegetables. Many of these foods contain both starch and fiber.
The digestible carbohydrates—starch and sugar—are broken into simpler molecules by enzymes in the saliva, in juice produced by the pancreas, and in the lining of the small intestine. Starch is digested in two steps. First, an enzyme in the saliva and pancreatic juice breaks the starch into molecules called maltose. Then an enzyme in the lining of the small intestine splits the maltose into glucose molecules that can be absorbed into the blood. Glucose is carried through the bloodstream to the liver, where it is stored or used to provide energy for the work of the body.
Sugars are digested in one step. An enzyme in the lining of the small intestine digests sucrose, also known as table sugar, into glucose and fructose, which are absorbed through the intestine into the blood. Milk contains another type of sugar, lactose, which is changed into absorbable molecules by another enzyme in the intestinal lining.
Fiber is undigestible and moves through the digestive tract without being broken down by enzymes. Many foods contain both soluble and insoluble fiber. Soluble fiber dissolves easily in water and takes on a soft, gel-like texture in the intestines. Insoluble fiber, on the other hand, passes essentially unchanged through the intestines.
2)Proteins. Foods such as meat, eggs, and beans consist of giant molecules of protein that must be digested by enzymes before they can be used to build and repair body tissues. An enzyme in the juice of the stomach starts the digestion of swallowed protein. Then in the small intestine, several enzymes from the pancreatic juice and the lining of the intestine complete the breakdown of huge protein molecules into small molecules called amino acids. These small molecules can be absorbed through the small intestine into the blood and then be carried to all parts of the body to build the walls and other parts of cells.
3)Fats. Fat molecules are a rich source of energy for the body. The first step in digestion of a fat such as butter is to dissolve it into the watery content of the intestine. The bile acids produced by the liver dissolve fat into tiny droplets and allow pancreatic and intestinal enzymes to break the large fat molecules into smaller ones. Some of these small molecules are fatty acids and cholesterol. The bile acids combine with the fatty acids and cholesterol and help these molecules move into the cells of the mucosa. In these cells the small molecules are formed back into large ones, most of which pass into vessels called lymphatics near the intestine. These small vessels carry the reformed fat to the veins of the chest, and the blood carries the fat to storage depots in different parts of the body.
4)Vitamins. Another vital part of food that is absorbed through the small intestine are vitamins. The two types of vitamins are classified by the fluid in which they can be dissolved: water-soluble vitamins (all the B vitamins and vitamin C) and fat-soluble vitamins (vitamins A, D, E, and K). Fat-soluble vitamins are stored in the liver and fatty tissue of the body, whereas water-soluble vitamins are not easily stored and excess amounts are flushed out in the urine.
5)Water and salt. Most of the material absorbed through the small intestine is water in which salt is dissolved. The salt and water come from the food and liquid you swallow and the juices secreted by the many digestive glands.
Information obtained from:
http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/Entry 6:Liver, Gallbladder and Pancreas
I have completed most of the stages in digestion and I would like to continue this topic with some further research on the liver, gallbladder and pancreas.
The liver (located under the rib cage in the right upper part of the abdomen), the gallbladder (hidden just below the liver), and the pancreas (beneath the stomach) are not part of the alimentary canal, but these organs are essential to digestion. The liver produces bile, which helps the body absorb fat. Bile is stored in the gallbladder until it is needed. The pancreas produces enzymes that help digest proteins, fats, and carbohydrates. It also makes a substance that neutralizes stomach acid. These enzymes and bile travel through special channels (called ducts) directly into the small intestine, where they help to break down food. The liver also plays a major role in the handling and processing of nutrients, which are carried to the liver in the blood from the small intestine.
Production of digestive juices
The digestive glands that act first are in the mouth—the salivary glands. Saliva produced by these glands contains an enzyme that begins to digest the starch from food into smaller molecules. An enzyme is a substance that speeds up chemical reactions in the body.
The liver (located under the rib cage in the right upper part of the abdomen), the gallbladder (hidden just below the liver), and the pancreas (beneath the stomach) are not part of the alimentary canal, but these organs are essential to digestion. The liver produces bile, which helps the body absorb fat. Bile is stored in the gallbladder until it is needed. The pancreas produces enzymes that help digest proteins, fats, and carbohydrates. It also makes a substance that neutralizes stomach acid. These enzymes and bile travel through special channels (called ducts) directly into the small intestine, where they help to break down food. The liver also plays a major role in the handling and processing of nutrients, which are carried to the liver in the blood from the small intestine.
Production of digestive juices
The digestive glands that act first are in the mouth—the salivary glands. Saliva produced by these glands contains an enzyme that begins to digest the starch from food into smaller molecules. An enzyme is a substance that speeds up chemical reactions in the body.
The next set of digestive glands is in the stomach lining. They produce stomach acid and an enzyme that digests protein. A thick mucus layer coats the mucosa and helps keep the acidic digestive juice from dissolving the tissue of the stomach itself. In most people, the stomach mucosa is able to resist the juice, although food and other tissues of the body cannot.
After the stomach empties the food and juice mixture into the small intestine, the juices of two other digestive organs mix with the food. One of these organs, the pancreas, produces a juice that contains a wide array of enzymes to break down the carbohydrate, fat, and protein in food. Other enzymes that are active in the process come from glands in the wall of the intestine.
The second organ, the liver, produces yet another digestive juice—bile. Bile is stored between meals in the gallbladder. At mealtime, it is squeezed out of the gallbladder, through the bile ducts, and into the intestine to mix with the fat in food. The bile acids dissolve fat into the watery contents of the intestine, much like detergents that dissolve grease from a frying pan. After fat is dissolved, it is digested by enzymes from the pancreas and the lining of the intestine.
Information obtained from:
1)http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/
2)http://kidshealth.org/parent/general/body_basics/digestive.htmlEntry 5:Large Intestine
The next part on my research is on the large intestine. Food continues it's journey from the small intestine to the large intestine. The large intestine is the last attraction in digestive tube and the location of the terminal phases of digestion. In comparison to other regions of the tube, there are huge differences among species in the relative size and complexity of the large intestine. From the small intestine, undigested food (and some water) travels to the large intestine through a muscular ring or valve that prevents food from returning to the small intestine. By the time food reaches the large intestine, the work of absorbing nutrients is nearly finished. The large intestine's main function is to remove water from the undigested matter and form solid waste that can be excreted. Material in the large intestine is mostly indigestible residue and liquid. Movements are due to involuntary contractions that shuffle contents back and forth and propulsive contractions that move material through the large intestine. The large intestine is made up of these three parts:
- The cecum is a pouch at the beginning of the large intestine that joins the small intestine to the large intestine. This transition area expands in diameter, allowing food to travel from the small intestine to the large. The appendix, a small, hollow, finger-like pouch, hangs at the end of the cecum. Doctors believe the appendix is left over from a previous time in human evolution. It no longer appears to be useful to the digestive process.
- The colon extends from the cecum up the right side of the abdomen, across the upper abdomen, and then down the left side of the abdomen, finally connecting to the rectum. The colon has three parts: the ascending colon; the transverse colon, which absorb fluids and salts; and the descending colon, which holds the resulting waste. Bacteria in the colon help to digest the remaining food products.
- The rectum is where feces are stored until they leave the digestive system through the anus as a bowel movement.
Information obtained from:
1)http://www.vivo.colostate.edu/hbooks/pathphys/digestion/largegut/index.html
2)http://kidshealth.org/parent/general/body_basics/digestive.html
3)http://www.gesa.org.au/digestive-system/large_intestine.cfm
4)http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookDIGEST.html#Stages%20in%20the%20Digestive%20Process
Saturday, July 12, 2008
Entry 4:The Small Intestine
This is my 4th entry on the Digestive System.I have posted quite a number of posts today as I am lagging in a few entries...I shall continue in the journey of food in the digestive tract.
The small intestine (also known as the small bowel) is the longest portion of the digestive tract - it is more than 6 meters long and is located within the middle of the abdomen. It has three sections, the duodenum, jejunum and ileum. Much of the small intestine is coiled and suspended in a thin layer of fat - which gives the intestine a lot of flexibility and mobility. Most substances in the food we eat need further digestion and must travel into the intestine before being absorbed. When it's empty, an adult's stomach has a volume of one fifth of a cup (1.6 fluid ounces), but it can expand to hold more than 8 cups (64 fluid ounces) of food after a large meal. By the time food is ready to leave the stomach, it has been processed into a thick liquid called chyme. A walnut-sized muscular valve at the outlet of the stomach called the pylorus keeps chyme in the stomach until it reaches the right consistency to pass into the small intestine. Chyme is then squirted down into the small intestine, where digestion of food continues so the body can absorb the nutrients into the bloodstream. Digestion of fats, proteins and carbohydrates contained in the foods you consume, is completed within the small intestine. The resulting nutrients produced are absorbed through the lining of the small intestine and transferred to the bloodstream. The small intestine is the site where most of the nutrients from ingested food are absorbed and is covered in wrinkles or folds called plicae circulares. The purpose of these wrinkles and projections is to increase surface area for absorption of nutrients. From the small intestine, undigested food (and some water) travels to the large intestine through a muscular ring or valve that prevents food from returning to the small intestine.
Information obtained from:
1)http://kidshealth.org/parent/general/body_basics/digestive.html
2)http://www.gesa.org.au/digestive-system/small_intestine.cfm
3)http://en.wikipedia.org/wiki/Small_intestine
The small intestine (also known as the small bowel) is the longest portion of the digestive tract - it is more than 6 meters long and is located within the middle of the abdomen. It has three sections, the duodenum, jejunum and ileum. Much of the small intestine is coiled and suspended in a thin layer of fat - which gives the intestine a lot of flexibility and mobility. Most substances in the food we eat need further digestion and must travel into the intestine before being absorbed. When it's empty, an adult's stomach has a volume of one fifth of a cup (1.6 fluid ounces), but it can expand to hold more than 8 cups (64 fluid ounces) of food after a large meal. By the time food is ready to leave the stomach, it has been processed into a thick liquid called chyme. A walnut-sized muscular valve at the outlet of the stomach called the pylorus keeps chyme in the stomach until it reaches the right consistency to pass into the small intestine. Chyme is then squirted down into the small intestine, where digestion of food continues so the body can absorb the nutrients into the bloodstream. Digestion of fats, proteins and carbohydrates contained in the foods you consume, is completed within the small intestine. The resulting nutrients produced are absorbed through the lining of the small intestine and transferred to the bloodstream. The small intestine is the site where most of the nutrients from ingested food are absorbed and is covered in wrinkles or folds called plicae circulares. The purpose of these wrinkles and projections is to increase surface area for absorption of nutrients. From the small intestine, undigested food (and some water) travels to the large intestine through a muscular ring or valve that prevents food from returning to the small intestine.
Information obtained from:
1)http://kidshealth.org/parent/general/body_basics/digestive.html
2)http://www.gesa.org.au/digestive-system/small_intestine.cfm
3)http://en.wikipedia.org/wiki/Small_intestine
Entry 3:The Stomach
I have learnt much more about the stomach today! At the beginning of today's research, I thought the stomach was just a muscular bag! However, now I do know the stomach is more than that. The stomach is an organ of digestion.The main function of the stomach is to process and transport food. After feeding, the contractile activity of the stomach helps to mix, grind and eventually evacuate small portions of chyme into the small bowel, while the rest of the chyme is mixed and ground. It has a saclike shape and is located between the esophagus and the intestines. Almost every animal has a stomach.The stomach muscles churn and mix the food with acids and enzymes, breaking it into much smaller, digestible pieces. An acidic environment is needed for the digestion that takes place in the stomach. Glands in the stomach lining produce about 3 quarts (2.8 liters) of these digestive juices each day. The lining of the stomach contains glands, which make and release (secrete) the stomach juices. The stomach juices contain an acid and a digestive enzyme called pepsin. These begin to flow as soon as we see or smell food, well before food even enters the stomach. The enzyme starts to break down (digest) proteins in the food so that the body can absorb them. The acid is necessary for the enzyme to work properly. It also helps to kill bacteria that might be in the food and so helps to protect against food poisoning.
There are other glands in the stomach lining that make thick mucus. This mucus helps to protect the stomach lining from being damaged by the acid and protein-digesting enzyme in the stomach juices. After about two hours in the stomach, the semi-liquid, partly digested food moves into the duodenum where it continues to be digested. The digested food then moves through the small intestine (small bowel) where the digested nutrients are absorbed into the body. The waste that is left behind then moves through to the large bowel where water is absorbed so that the waste matter begins to solidify into the faeces or stool.
Information obatained from: 1)http://kidshealth.org/parent/general/body_basics/digestive.html
2)http://www.mamashealth.com/organs/stomach.asp
3)http://www.enel.ucalgary.ca/People/Mintchev/stomach.htm
4)http://www.cancerhelp.org.uk/help/default.asp?page=3905
There are other glands in the stomach lining that make thick mucus. This mucus helps to protect the stomach lining from being damaged by the acid and protein-digesting enzyme in the stomach juices. After about two hours in the stomach, the semi-liquid, partly digested food moves into the duodenum where it continues to be digested. The digested food then moves through the small intestine (small bowel) where the digested nutrients are absorbed into the body. The waste that is left behind then moves through to the large bowel where water is absorbed so that the waste matter begins to solidify into the faeces or stool.
Information obatained from: 1)http://kidshealth.org/parent/general/body_basics/digestive.html
2)http://www.mamashealth.com/organs/stomach.asp
3)http://www.enel.ucalgary.ca/People/Mintchev/stomach.htm
4)http://www.cancerhelp.org.uk/help/default.asp?page=3905
Wednesday, July 9, 2008
Entry 2:The Oesophagus
I have decided to continue on my research on the Digestive System today and I started on swallowing and the Oesophagus! Swallowing, which is accomplished by muscle movements in the tongue and mouth, moves the food into the throat, or the pharynx. The pharynx, a passageway for food and air, is about 5 inches (12.7 centimeters) long. A flexible flap of tissue called the epiglottis reflexively closes over the windpipe when we swallow to prevent choking.The oesophagus(British spelling), which is sometimes known as the gullet, is an organ found in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. It is usually around 25 to 30 cm long, connecting the mouth to the stomach. Food is passed through the oesophagus by using the process of peristalsis. Specifically, it contains the pharynx, which is the body cavity that is common to the digestive factory and respiratory system with the stomach, where the second stage of digestion is initiated. The oesophagus is lined with mucuos membrane, and is more deeply lined with muscle that acts with peristaltic action to move swallowed food down to the stomach. A person normally isn't aware of the movements of the esophagus, stomach, and intestine that take place as food passes through the digestive tract. At the end of the esophagus, a muscular ring or valve called a spincter allows food to enter the stomach and then squeezes shut to keep food or fluid from flowing back up into the oesophagus.
Information obtained from:1)http://en.wikipedia.org/wiki/Oesophagus
2)http://kidshealth.org/parent/general/body_basics/digestive.html
Information obtained from:1)http://en.wikipedia.org/wiki/Oesophagus
2)http://kidshealth.org/parent/general/body_basics/digestive.html
Wednesday, July 2, 2008
Entry 1:Digestion and Salivary Glands
Digestion is the breaking down of food in the body, into a form that can be absorbed and used or excreted. It is also the process by which the body breaks down food into smaller components that can be absorbed by the blood stream.The digestive system is made up of the digestive tract,which is a series of hollow organs joined in a long, twisting tube from the mouth to the anus,and to other organs that help the body break down and absorb food.Even before you eat, when you smell a tasty food, see it, or think about it, digestion begins.
Part 1:Salivary Glands
The salivary glands are part of the digestive system. They do not function mechanically, but subject to the control of the brain.There are 3 pairs of salivary glands, of which one is in the front ear, one under the tongue, and the last one under the lower jaw. One interesting fact about the largest salivary glands is that it secrates about 23,600 litres of saliva in a lifetime!Each salivary gland has a special job too. The parotid gland, which is also the largest one, secretes large quantities of watery saliva.The main purpose of this saliva is to dilute and to moisten the food well.Which of the salivary glands will produce the most saliva also depends on the food we take in. Lower glands will function when we are chewing on food which do not need to be moistened, and the parotid gland goes to work and produce large quantities of watery saliva for dry food. When the food is ready to be swallowed, the tongue then pushes a tiny bit of food called a bolus toward the back of your throat into the opening of the esophagus, the second part of the digestive tract. I shall continue on this in my next entry.
Information obtained from:1)http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/
2)http://en.wikipedia.org/wiki/Digestive_system
3)Encyclopedia:Tell Me Why
4)http://kidshealth.org/kid/htbw/digestive_system.html
Part 1:Salivary Glands
The salivary glands are part of the digestive system. They do not function mechanically, but subject to the control of the brain.There are 3 pairs of salivary glands, of which one is in the front ear, one under the tongue, and the last one under the lower jaw. One interesting fact about the largest salivary glands is that it secrates about 23,600 litres of saliva in a lifetime!Each salivary gland has a special job too. The parotid gland, which is also the largest one, secretes large quantities of watery saliva.The main purpose of this saliva is to dilute and to moisten the food well.Which of the salivary glands will produce the most saliva also depends on the food we take in. Lower glands will function when we are chewing on food which do not need to be moistened, and the parotid gland goes to work and produce large quantities of watery saliva for dry food. When the food is ready to be swallowed, the tongue then pushes a tiny bit of food called a bolus toward the back of your throat into the opening of the esophagus, the second part of the digestive tract. I shall continue on this in my next entry.
Information obtained from:1)http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/
2)http://en.wikipedia.org/wiki/Digestive_system
3)Encyclopedia:Tell Me Why
4)http://kidshealth.org/kid/htbw/digestive_system.html
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