how did the dodo bird extinct

this is the very last post on ecology and the very last post of biology journal.

as mentioned in the previous post, i mentioned that the dodo bird is extinct due to the destruction of the forest (which cut off the Dodo's food supply), and the animals that the sailors brought with them, including cats, rats, and pigs, which destroyed Dodo nests.

so now i would like to further elaborate on them.

After the remote island became inhabited by humans, the dodo's fate was sealed. The poor fowl had lived in relative isolation for so long that it had few defenses and proved to be easy prey for humans and the animals they brought with them. The flightless bird was hunted for sport and food by humans, and its eggs, laid individually in nests on the ground, were devoured by dogs, cats, and pigs. By 1681, the entire species was wipe out. Two similar species were discovered on nearby islands, but sadly, they fared no better and were both extinct by 1750.

On an interesting side note, not only did the extinction of the dodo deprive the world of one of nature's most curious creations, it almost led to the extinction of yet another species, a certain type of tree whose seeds could only germinate after passing through the digestive tract of the dodo. With the disappearance of the dodo, the tree was slowly dying out. There were only 13 trees left when it was discovered that turkeys could also be used to help the seeds activate, and the tree, now known as the dodo tree, has avoided extinction for the time being.

so from here we can link it to the posts on extinction. it was due to the hunters that wiped on all of them. worse still, their generation of babies are also wiped out by the dogs, cats and pigs. this lead to a zero replacement fertility level.

http://ask.yahoo.com/20030715.html

about dodo bird

The Dodo is a lesson in extinction. First sighted around 1600 on Mauritius, an island in the Indian Ocean, the Dodo was extinct less than eighty years later.

there are no complete Dodo specimens. Some of the birds may have been eaten by the Dutch sailors who discovered them. However, the primary causes of their extinction were the destruction of the forest (which cut off the Dodo's food supply), and the animals that the sailors brought with them, including cats, rats, and pigs, which destroyed Dodo nests.

The Dodo's stubby wings and heavy, ungainly body tell us that the bird was flightless. Moreover, its breastbone is too small to support the huge pectoral muscles a bird this size would need to fly. Yet scientists believe that the Dodo evolved from a bird capable of flight into a flightless one. When an ancestor of the Dodo landed on Mauritius, it found a habitat with plenty of food and no predators. It therefore did not need to fly, and, as flying takes a great deal of energy, it was more efficient for the bird to remain on the ground. Eventually, the flightless Dodo evolved.

Scientists at the American Museum of Natural History and other institutions around the world continue to study and document the impact of human activities on the environment. It is hoped that the lesson of the Dodo can help prevent similar extinctions, and aid us in preserving the diversity of life on earth.

http://www.amnh.org/exhibitions/expeditions/treasure_fossil/Treasures/Dodo/dodo.html?dinos

more about extintion and ecology

take a look at this video. i apologize for the inconvience cause becuase i could not upload it.

http://www.youtube.com/watch?v=XbOXUza9ZeE

was thinking about our collective denial of the environmental crisis we’re creating, when I read a blog post by Nicola-Frank Vachon at The Solemn Monkey. (To understand the title, see the very worthwhile video on the “About me” page.) Besides an artistic essay which led me to confront the thought of our own self-destruction, it featured the video below. From the Species Alliance, I think it’s remarkably persuasive in driving home its point about the huge surge in extinctions we’re seeing today.
Our earth has seen five prior waves of mass extinction, the last one being that which eliminated the dinosaurs. This “sixth extinction,” (pdf) as many scientists now refer to it, is the result of human activity, with causes including climate change and deforestation. Key among the underlying drivers of those causes are, of course, the topics we examine here: human population growth, our growing rates of resource consumption, and the drive for unceasing economic growth.
The video made me wonder if the specter of mass extinction, especially when effectively presented, might be enough to break through some of our denial. I would think many people would sense intuitively that a world with half as many species as we now enjoy would be grimly impoverished. Would it be livable? I hope we don’t have to find out first hand. Does the subject of mass extinction have a unique place in our toolbox of ways to wake people up to the realities of our ecological crisis?

an article on ecosystem - "Ecosystem consequences of extinction different than thought"

The loss of seemingly inconsequential animal species from the sea floor has given scientists a new insight into ecosystem impacts that occur when species become extinct.

An international team of scientists – led by the University of Aberdeen - have found that the consequences of biodiversity loss could be very different to what was previously thought.

Researchers say this is because they have discovered that it is the cause of extinction and order in which species are lost - rather than simply the number of species that go extinct - which ultimately determines the ecological impact of extinction.

Rapid changes in biodiversity are occurring globally, yet the ecological impacts of diversity loss remain poorly understood.

Marine coastal ecosystems are among the most productive and diverse communities on Earth and are of significant importance to the regulation of climate, nutrients, and the food chain.

However, the contributions that coastal ecosystems make to these ecological processes are compromised by man’s activities, such as overfishing, habitat destruction and pollution.

Bottom dwelling marine organisms are particularly vulnerable to extinction because they are often unable to avoid disturbance. These organisms are important because they churn up sediments from the bottom of the ocean – a process referred to as bioturbation - which results in nutrients being returned to the water column where they are vital for other species in the food web.

Dr Martin Solan, from the University of Aberdeen’s Oceanlab, led the research which involved collaborators from America and Canada. He said: “Organisms living in the seabed, such as clams, worms and shrimps may not seem that important, but they are essential for regulating and recycling the planet’s resources.”

Scientists have discovered that the effects of extinctions in general can differ from what they had previously predicted. This is because the characteristics of a species that most greatly influence vital ecosystem processes, such as bioturbation, often also determine susceptibility to extinction.

Dr Solan said: “Our findings suggest that previous predictions of what happens to an ecosystem following extinction may be, for better or for worse, far from the reality.”

Current predictions of what happens to an ecosystem following extinction have assumed that species are lost completely at random. This is not necessarily the case - some drivers of extinction target particular attributes of certain species more than others.

Dr Solan added: “We have known for some time that there are general ecological consequences of species extinction. What we didn’t appreciate is that the point at which bioturbation loss begins, depends on both the cause of extinction and, critically, the order in which species are lost”.
The research team based their findings on communities of invertebrate species (like clams, shrimps, worms) from marine samples collected in Inner Galway Bay, Ireland.

The team used the Galway data to mathematically simulate the random extinction of species versus non-random extinctions - where species were lost according to how rare, big or sensitive to pollution they are. These characteristics matter because they are important for determining the degree of bioturbation.

The team also defined how an ecosystem may respond to extinction. The best case scenario assumed that surviving species altered their bioturbation behaviour in order to compensate for the species which had become extinct. The worst case scenario assumed the surviving community failed to respond.

Dr Solan said: “We chose these alternative scenarios of extinction in order to mimic as closely as possible the full range of consequences that known extinction drivers may have on the communities of the marine environment.

“However, our findings are equally applicable to other ecosystems where the cause of extinction targets particular biological characteristics.”
The team’s findings have important implications for the conservation of biological resources and habitat.

Dr Solan added: “If we wish to predict the ecological impacts of extinction, we must first understand why species are at risk and how this risk correlates with the role they play in the ecosystem. It is only when we know these details that we can hope to effectively protect our ecological heritage.”

The team’s findings Extinction and Ecosystem Function in the Marine Benthos appear in the Journal Science.

The research team included the University of Aberdeen; University of California; Ohio Wesleyan University, Delaware; University of Maryland Center for Environmental Science; University of Washington and University of British Columbia.

http://www.abdn.ac.uk/mediareleases/release.php?id=54

introduction to extinction

The idea of individual species becoming extinct is quite familiar; indeed it is a rather sad indictment of our stewardship of the planet that we are all too familiar with extinction. But, in fact, extinction is a rather complex phenomenon. At one end of the continuum we have the notion of a population of organisms evolving into something else. Here, the disappearance of the original phenotype might be accomplished by nothing more than natural turn-over of the generations (anagenesis).

At the opposite end of the spectrum, we have the mass extinctions, where huge proportions of the earth biota disappear more or less simultaneously, within an interval that is, in some sense, short. At least some of the more sensational explanations for these phenomena require the wholesale killing of individual organisms.

Between these two extremes we have a range of possibilities, further complicated by the vagaries of the fossil record and our imperfect interpretation thereof. And always, even in the case of the KT event which cannot be "explained away" in its entirety by meteorite impact, there is the enigma of underlying cause.


Working Definitions

For our purposes, extinction of a single taxon ?whether a species or higher level taxon ?is accomplished when the last representative of that taxon dies. Of course we could also distinguish the point at which the organism was no longer able to reproduce (e.g. when the population density of a dioecious species drops below its reproductive threshold) but any such subtlety is pointless: The fossil record is not a good witness to the fate of individuals, so our notions of extinction are necessarily approximate. In practice, to the paleontologist, extinction is the last (most recent) occurrence of an identifiable fossil.

We have more difficulty with the concept of mass extinctions. Ward 2000 (pp. 6-7) offers the definition that mass extinction events are geologically short intervals of intense species extinction. However, this definition admits events such as the decimation of the South American marsupial fauna following the establishment of a land bridge with North America in the late Pliocene, which is almost certainly not his intention. Of course such events are also interesting extinction phenomena. But to properly capture the idea of Mass Extinction, it also seems necessary that a mass extinction should be global in extent and involve participants?from widely diverse taxonomic groups.

http://www.peripatus.gen.nz/paleontology/extinction.html

Energy and nutrient transfers

All living organisms require energy. The ultimate source of all this energy is the sun. Solar energy is trapped by plants, and then transferred from organism to organism in a food chain. At each stage in this transfer much of the energy is lost to the environment.

Living organisms also require nutrient elements - in particular carbon and nitrogen - which they take from the environment. If this were just a one-way process, ecosystems would soon run out of these nutrients; but in fact they are returned to the environment, with the help of bacteria, via nutrient cycles

In every ecosystem, energy is transferred along food chains from one trophic level to the next. But not all the energy available to organisms at one trophic level can be absorbed by organisms at the next one: in fact the amount of available energy decreases dramatically at each level. Why?
Some of the available energy goes into growth in biomass and the production of offspring: this energy does become available to the next trophic level. However most of the available energy is used up in other ways:
Some is used up at the first trophic level as a result of photosynthesis, which uses up lots of solar energy in making glucose.
Some is used up in respiration, and given off as heat
Some is lost, in the form of biological material and heat, through excretion. (This energy is actually transferred to the decomposer food chain: more about this later!)
Some is used for movement and transport.
All the energy used in these ways returns to the environment, and is not available to the next trophic level. so much energy is lost at each level that however much you start off with it is almost all gone by the fourth trophic level

http://www.bbc.co.uk/schools/gcsebitesize/biology/livingthingsenvironment/2energyandnutrienttransferrev2.shtml

secondary consumers (canivores)

Secondary Consumers consume the primary consumers. Energy that had been used by the primary consumers for growth and storage is thus absorbed into the secondary consumers through the process of digestion. As with primary consumers, secondary consumers convert this energy into a more suitable form (ATP) during respiration. Again some energy is lost from the system, since energy which the primary consumers had used for respiration cannot be utilised by the secondary consumers.

secondary consumers can also be named as canivores

Characteristics commonly 'associated' with carnivores include organs for capturing and disarticulating prey (teeth and claws serve these functions in many vertebrates) and status as a predator. In truth, these assumptions may be misleading, as some carnivores do not hunt and are scavengers (though most hunting carnivores will scavenge when the opportunity exists). Thus they do not have the characteristics associated with hunting carnivores. Carnivores have comparatively short digestive systems as they are not required to break down tough cellulose found in plants.

http://en.wikipedia.org/wiki/Carnivore
http://en.wikipedia.org/wiki/energyflow

primary consumers (or herbivore)

herbivory is generally restricted to animals eating plants. Fungi, bacteria and protists that feed on living plants are usually termed plant pathogens. Microbes that feed on dead plants are saprotrophs. Flowering plants that obtain nutrition from other living plants are usually termed parasitic plants. More generally, organisms that feed on autotrophs in general are known as primary consumers.


A herbivore is an animal that is adapted to eat primarily plant matter (rather than meat). Although such animals are sometimes referred to as being vegetarian, this term is more properly reserved for humans who choose not to eat meat as opposed to animals that are unable to make such choices. The diets of some herbivorous animals vary with the seasons, especially in the temperate zones, where different plant foods are most available at different times of year.

There is a misperception that if an animal is herbivorous, it represents less danger to humans than a carnivore (or, sometimes, no danger at all). This is not logically sound; few animals, even carnivores, will seek humans as a food source, but any animal will attack a human if necessary to defend itself. For example, in national parks such as the United States' Yellowstone Park, bison represent significantly more danger to humans than wolves, which are likely to avoid people. Of Africa's Big Five game (a term coined by hunters in Africa to refer to the five most dangerous animals to hunt: Rhinoceros, Leopard, Cape Buffalo, Elephant and Lion), three are herbivores.

Herbivores form an important link in the food chain as they transform the sun's energy stored in the plants to food that can be consumable by carnivores and omnivores up the food chain. As such, they are termed the primary consumers in the food chain.


Feeding strategies


Herbivores differ in the extent, specificity and nature of their feeding.

They can be grouped according to which part of the plant they eat: frugivores which eat mainly fruit; folivores, which specialize in eating leaves; nectarivores, which feed on nectar; among herbivorous insects and other arthropods, the level of feeding specialization can be far more fine-tuned, including seed-eaters ("granivores"), pollen-eaters ("palynivores"), plant fluid-feeders ("mucivores"), and those specialized to feed on wood ("xylophages") or roots ("rhizophages"). In other animals, the degree of specialization is not so advanced, however, and many fruit- and leaf-eating animals also eat other parts of plants, notably roots and seeds.

The techniques used to get at the foodstuff are wide and varied, and include the "pierce and suck" technique, surface fluid feeding, hole feeding, margin feeding and skeletonisation.

http://en.wikipedia.org/wiki/Primary_consumers

FOOD WEBS

FOOD WEBS
A food chain shows how each living thing gets its food. Some animals eat plants and some animals eat other animals. For example, a simple food chain links the trees & shrubs, the giraffes (that eat trees & shrubs), and the lions (that eat the giraffes). Each link in this chain is food for the next link. A food chain always starts with plant life and ends with an animal.
Plants are called producers because they are able to use light energy from the Sun to produce food (sugar) from carbon dioxide and water.
Animals cannot make their own food so they must eat plants and/or other animals. They are called consumers. There are three groups of consumers.

Animals that eat ONLY PLANTS are called herbivores (or primary consumers).

Animals that eat OTHER ANIMALS are called carnivores.
carnivores that eat herbivores are called secondary consumers
carnivores that eat other carnivores are called tertiary consumerse.g., killer whales in an ocean food web ... phytoplankton → small fishes → seals → killer whales

Animals and people who eat BOTH animals and plants are called omnivores.

Then there are decomposers (bacteria and fungi) which feed on decaying matter.

These decomposers speed up the decaying process that releases mineral salts back into the food chain for absorption by plants as nutrients.
Image Map of the Nitrogen Cycle - What happens in the soil? Do you know why there are more herbivores than carnivores?

In a food chain, energy is passed from one link to another. When a herbivore eats, only a fraction of the energy (that it gets from the plant food) becomes new body mass; the rest of the energy is lost as waste or used up by the herbivore to carry out its life processes (e.g., movement, digestion, reproduction). Therefore, when the herbivore is eaten by a carnivore, it passes only a small amount of total energy (that it has received) to the carnivore. Of the energy transferred from the herbivore to the carnivore, some energy will be "wasted" or "used up" by the carnivore. The carnivore then has to eat many herbivores to get enough energy to grow.

Because of the large amount of energy that is lost at each link, the amount of energy that is transferred gets lesser and lesser ...
The further along the food chain you go, the less food (and hence energy) remains available.

The above energy pyramid shows many trees & shrubs providing food and energy to giraffes. Note that as we go up, there are fewer giraffes than trees & shrubs and even fewer lions than giraffes ... as we go further along a food chain, there are fewer and fewer consumers. In other words, a large mass of living things at the base is required to support a few at the top ... many herbivores are needed to support a few carnivoresMost food chains have no more than four or five links.

There cannot be too many links in a single food chain because the animals at the end of the chain would not get enough food (and hence energy) to stay alive.

Most animals are part of more than one food chain and eat more than one kind of food in order to meet their food and energy requirements. These interconnected food chains form a food web.

Possible food chains / food webs: Desert Coniferous Forest Deciduous Forest Temperate Rainforest A change in the size of one population in a food chain will affect other populations.

This interdependence of the populations within a food chain helps to maintain the balance of plant and animal populations within a community. For example, when there are too many giraffes; there will be insufficient trees and shrubs for all of them to eat. Many giraffes will starve and die. Fewer giraffes means more time for the trees and shrubs to grow to maturity and multiply. Fewer giraffes also means less food is available for the lions to eat and some lions will starve to death. When there are fewer lions, the giraffe population will increase.

http://www.vtaide.com/png/foodchains.htm

further explaination ecosystem

The U.S. Fish and Wildlife Service defines an ecosystem as a geographic area and all its living components (e.g., people, plants, animals, and microorganisms), their physical surroundings (e.g., soil, water, and air), and the natural cycles that sustain them (e.g., precipitation, drought, fire, grazing). The term ecosystem was coined in 1935 by the British ecologist Sir Arthur George Tansley, who described natural systems in "constant interchange" among their living and non-living parts.

Since that time, scientists have devoted much time and resources toward gaining a better understanding of ecosystem structure and function from the global to localized scale. Part of this work has included developing a National Hierarchical Framework for classifying and mapping ecosystems at different geographical scales. Recognition of ecosystem scale and hierarchy provides managers context from which ecosystem assessment, analysis, and management can occur.

Sitting at the top of the ecosystem hierarchy is the planet's entire living environment, known as the Biosphere. Within the biosphere there are several categories of living communities referred to as ecological units (e.g., domains, divisions, provinces, section, sub-section, etc). Ecological units are generally characterized by their dominant vegetation, such as grasslands, forests, or deserts, and by their different biological and physical potentials.

The structure and function of an ecosystem is largely determined by energy, moisture, nutrient, and disturbance regimes, which in turn are influenced by a variety of biological and non-biological factors, including climate, geology, flora, fire, hydrology, and wind. Ecosystem function depends on inputs, outputs, and the cycling of materials and energy

Ecosystem function is often described biologically in terms of trophic levels. Plant matter in an ecosystem makes up the first trophic level and thus are known as primary producers. A plant's ability to convert energy from the sun into food is a process known as photosynthesis. The second trophic level of an ecosystem, the primary consumers (herbivores), are the animals and insects that obtain their energy solely by eating the primary producers (plants). The third trophic level is composed of secondary consumers, carnivorous animals that feed on herbivores. At the fourth level are the tertiary consumers, carnivores that feed on other carnivores. Finally, the fifth trophic level consists of the decomposers, organisms such as fungi and bacteria that break down dead or dying matter into nutrients that can be used again.

Some or all of these trophic levels combine to form what is known as a food web, the ecosystem's mechanism for circulating and recycling energy and materials. In aquatic ecosystems for instance, microscopic plants (algae) use sunlight to produce energy in the form of carbohydrates. Primary consumers such as zooplankton and small fish feed on the microscopic plant matter, and are in turn eaten by secondary consumers, larger fish such as salmon and trout. Bears play the role of the tertiary consumers in the aquatic food web by catching and eating the salmon and trout. Bacteria and fungi that feed on and decompose the salmon and trout carcasses left behind by the bear enable chemical nutrients tied up in the fish to leach back into the soil and water, where they are absorbed by algae and plants. In this way energy, originally captured by the algae from sunlight, is recycled back into the ecosystem through a complex food web.

http://www.fws.gov/midwest/EcosystemConservation/ecosystem.html

What is an Ecosystem?

Within all species, individuals interact with each other - feeding together, mating together, and living together. Some species have a pecking order as well, and each individual has a role to play within it.

However, it is not only individuals within a species that interact. Different species of animals interact with each other all the time. For instance, animals eat other animals through their interactions in a food web. But plants are included in this web as well as they, too, are eaten by animals.
What would happen if the weather were really cold all the time? Well, not all species of animals, plants and bacteria would be able to survive. What differences are there between species who live in the Rocky Mountains and those who inhabit the Sahara desert? Landscape also determines where plants and animals might live. But what, exactly, is an ecosystem? An ecosystem is a geographical area of a variable size where plants, animals, the landscape and the climate all interact together.

The whole earth's surface can be described by a series of interconnected ecosystems. All living beings form and are part of ecosystems. They are diverse and always changing. Within an ecosystem, all aspects of the environment (both living things and their non-living settings) interact and affect one another. Every species affects the lives of those around them.
A small ecosystem in the boreal forest might look something like this: in the summertime, trees in forests (that produce oxygen used by living things through photosynthesis) lower the temperature in the forest for communities in the hot summer months. In turn, some members of the communities will probably feed upon the tree to gain nourishment, thus affecting or stunting the tree's growth.

Different areas in the world house different ecosystems. For example, you won't find an elephant or a tropical rainforest in Alberta! The different world ecological units are called biomes and they each have different flora, fauna, landscapes and weather patterns. An ecosystem is not the same thing as a biome. A biome is a large unit that is home to many different ecosystems. Within Alberta, there are six different biomes that each have their own specific flora and fauna distribution. These regions are: Grassland, Parkland, Boreal Forest, Foothill, Rocky Mountain and the Canadian Shield, all indicated on the map of Alberta's Regions.

http://www.abheritage.ca/abnature/Ecosystems/intro.htm

ecosystem

from this post onwards, it will be about ecosystem. here is the question:


"how does the energy transfer and nutrient cycles in ecosystem affect the extintion of animals such as the dodo bird?"

it will be break up into different parts
1)defintion on ecosystem
2)information about food web
3)primary consumers and secondary consumers
4)energy transfer in ecosystem
5)extinction of animals
6)focus on how did the dodo bird extinct

more about contraception

this is the very last post on issues on sex.

having so much of information of contraception and vasectomy, along the way as i research, i notice that there is this thing called "emergency contraception" and i think it would be nice to further add in to this biology journal and also to satisfy my curosity.

so what is emergency contraceptive method?

Since the mid 1960s, the use of certain oral contraceptives has been shown to be effective in preventing pregnancy. Two hormonal regimens have proved to be both safe and effective for emergency contraception: combined oral contraceptives and progestogen-only pills. Both can be taken for up to 120 hours after unprotected intercourse. Emergency contraception represents a second chance to prevent an unwanted pregnancy after unprotected sex, and it is particularly responsive to the needs of youths and of women who have been coerced into intercourse.Despite the demonstrated safety and efficacy of emergency contraception, its acceptance by providers and the public, and its inclusion on the WHO's essential drug list, emergency contraception is not widely available in many developing countries (Langer and others 1999).

so thats all for issues on sex the next topic will be on ecosystem.

risk

Risk with vasectomy are few. No death has ever been attributed to this procedure. On the other hand, tubal ligation, a frequently performed surgical sterilization procedure in women, is associated with no fewer than 20 deaths per year. These unnecessary deaths occur because of the risks of the procedure itself, anesthesia complications, and increased ectopic pregnancy rates.

Complications with vasectomy are usually related to bleeding or infection. Prolonged pain sometimes occurs as a result of inflammation along the vas due to sperm leakage (sperm granuloma) or congestion of sperm at the epididymis (epididymitis). These conditions usually go away with rest and anti-inflammatory medication.

Some earlier studies suggested that vasectomy may be associated with an increased risk of heart disease and prostate cancer. According to the National Institutes of Health, research that examined this issue found no evidence that men with vasectomies were more likely than others to develop heart disease or any other immune illness. Other studies, including a recent study of 2,000 men, have shown that the risk of prostate cancer is not increased among vasectomized men.


Fears about the procedure:

Fear can prevent a man from choosing a vasectomy. The following issues are addressed to help a man understand that a vasectomy procedure is simple and safe:

Fear of pain - Men don’t like to think of any procedure near their genitals. Fact: What men need to understand is that an anesthetic is used to numb the area. There is usually no pain or just some pulling after the anesthetic is given. The procedure is usually so well tolerated that upon completion of the procedure, men are frequently surprised that it is over.

Fear of loss of masculinity - Fact: A vasectomy does not affect manliness. A vasectomy does not affect the blood and hormone supply to the penis. The amount and appearance of semen ejaculated will not change noticeably. Of course, during the recovery process, men may be sore, thus making sex less desirable. Later, some men report that sex is actually more enjoyable without the threat of pregnancy. Women may appreciate that their partners have chosen to take the responsibility for sterility (permanent birth control).

Fear of failure of the procedure - Fact: Except for complete abstinence, no method is more effective than vasectomy in preventing pregnancy.

http://www.emedicinehealth.com/vasectomy/page2_em.htm
Belker AM, Thomas AJ Jr, Fuchs EF. Results of 1,469 microsurgical vasectomy reversals by the Vasovasostomy Study Group. J Urol. Mar 1991;145(3):505-11Testes/testicles - Located in the scrotum, the male reproductive glands that produce sperm and male hormonedefintion taken fromMarquette CM, Koonin LM, Antarsh L. Vasectomy in the United States, 1991. Am J Public Health. May 1995;85(5):644-9.

contraception through vasectomy

the operation is performed using local anaesthetic, although some men prefer a general anaesthetic. The testicles are shaved. A small cut is made on either side of the scrotum and the surgeon then loops out each vas deferens.The three different vasectomy techniques include:Cutting, and sometimes tying, the vas deferensRemoving a small piece from each vas deferensSealing the vas deferens with heat using a diathermy machine.

After the operation
The scrotum will most likely be bruised and tender after the operation. It is important to rest for a couple of days and avoid running, swimming or any other physical activity. Sex can be resumed after a few days. If the testicles become swollen or painful, or if the wound sites start to weep, there may be an infection. Treatment options include antibiotics and dressings. Occasionally a man will experience prolonged groin tenderness.

Failure rates
The chances of pregnancy after having a vasectomy are around one in 1,000. However, it can take some time for the testicles to reabsorb existing sperm after a vasectomy. It is important to use another form of contraception until tests show zero sperm in the ejaculate. This usually takes three to four months but can occasionally be up to six months.

Reversing the operation
A man usually opts for a vasectomy after he and his partner have completed their family. However, it is common for men entering a second or subsequent relationship to want to conceive with their current partner. Although reversals are nearly always technically possible, they have a variable success rate. The likelihood of a successful reversal depends on the way the vasectomy was performed and the length of time since the operation. As time goes on, the chances of sperm functioning normally are reduced. Some surgeons recommend that a man make sperm bank deposits before having a vasectomy, just in case he changes his mind in the future about having more children. The cost of vasectomy reversal is not covered by Medicare

.http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Contraception_vasectomy?openhttp://www.emedicinehealth.com/vasectomy/article_em.htmVas

deferens - The 2 muscular tubes that carry sperm from the testicle and epididymis to the urinary tract and out the urethra; each referred to as a vas and together as vasaglossary taken from

http://www.emedicinehealth.com/vasectomy/article_em.htm

vasectomy

defintion-A vasectomy is a surgical procedure that makes a man sterile, or unable to get a woman pregnant. It is generally considered to be at least as effective as female sterilization and is simpler to perform, safer, and less costly.

5 questions about vasectomy

1)How is vasectomy done?
In the conventional approach, a physician makes one or two small incisions, or cuts, in the skin of the scrotum, which has been numbed with a local anesthetic. The vas is cut, and a small piece may be removed. Next, the doctor ties the cut ends and sews up the scrotal incision. The entire procedure is then repeated on the other side.A newer method, devised by a Chinese surgeon, has been widely used in China since 1974. This so-called nonsurgical or no- scalpel vasectomy was introduced into the United States in 1988, and many doctors are now using the technique worldwide.In a no-scalpel vasectomy, the doctor feels for the vas under the skin of the scrotum and holds it in place with a small clamp. A special instrument is then used to make a tiny puncture in the skin and stretch the opening so the vas can be cut and tied. This approach produces very little bleeding, and no stitches are needed to close the punctures, which heal quickly by themselves. The newer method also causes less pain and fewer complications than conventional vasectomy.

2)What are the side effects of vasectomy?
A major study of vasectomy side effects occurring within 8 to 10 years after the procedure was published in the British Medical Journal in 1992. Investigators questioned 10,590 vasectomized men, and an equal number of nonvasectomized men, to determine if they had developed any of 99 different disorders. After a total of 182,000 person-years of follow-up, only one condition, epididymitis/orchitis was found to be more common after vasectomy. This local inflammation most often occurs during the first year after surgery. Treated with heat, the condition usually clears within a week.

3)What are the disadvantages of vasectomy?
The chief advantage of vasectomy--its permanence--is also its chief disadvantage. The procedure itself is simple, but reversing it is difficult, expensive, and often unsuccessful. Researchers are studying new methods of blocking the vas that may produce less tissue damage and scarring and might thus permit more successful reversal. But these methods are all experimental, and their effectiveness has not yet been confirmed.

4)Does vasectomy protect against HIV and other STDs?
Although the procedure is extremely effective in preventing pregnancy, vasectomy does not offer any protection whatsoever against HIV/AIDS or any other sexually transmitted diseases (STDs). Consequently, it is important that vasectomized men continue to use condoms, preferably latex, which offer considerable protection against the spread of disease, in any sexual encounter that carries the risk of contracting or transmitting infection.

5)What is the official view of vasectomy?
The NIH expert panel concluded there is insufficient basis for recommending any change in current clinical or public health practice. Providers should continue to offer vasectomy and to perform the procedure, the panel said. Vasectomy reversal is not warranted to prevent prostate cancer, and screening for prostate cancer should not be any different for men who have had a vasectomy than for those who have not undergone the procedure.

http://www.nichd.nih.gov/health/topics/vasectomy.cfmhttp://www.medicinenet.com/vasectomy/page5.htm
glossary :
epididymitis/orchitis- painful, swollen, and tender epididymis or testisdefinition taken from
Scrotum - The sac that contains the testicles, epididymis, and vas deferens
Semen - The combination of sperm and glandular fluid released by the urethra when a man ejaculates; normally a mixture of less than 1% sperm and 99% seminal fluid

http://www.netdoctor.co.uk/diseases/facts/epididymitis.htm