Human Cells--MITOCHONDRIA

Mitochondria are known as the powerhouses of the cell. They are organelles that act like a digestive system that takes in nutrients, breaks them down, and creates energy for the cell. The process of creating cell energy is known as cellular respiration. Most of the chemical reactions involved in cellular respiration happen in the mitochondria. A mitochondrion is shaped perfectly to maximize its efforts. Mitochondria are very small organelles. You might find cells with several thousand mitochondria. The number depends on what the cell needs to do. If the purpose of the cell is to transmit nerve impulses, there will be fewer mitochondria than in a muscle cell that needs loads of energy. If the cell feels it is not getting enough energy to survive, more mitochondria can be created. Sometimes they can even grow, move, and combine with other mitochondria, depending on the cell's needs.
Mitochondria Structure
Mitochondria have two membranes (not one as in other organelles). The outer membrane covers the organelle and contains it. The inner membrane folds over many times (cristae). That folding increases the surface area inside the organelle. Many of the chemical reactions happen on the inner membrane of the mitochondria. The increased surface area allows the small organelle to do as much work as possible. If you have more room to work, you can get more work done. Similar surface area strategies are used by microvilli in your intestinal cells. The fluid inside of the mitochondria is called the matrix.
Using Oxygen to Release Energy

How are mitochondria used in cellular respiration? The matrix is filled with water (H2O) and proteins (enzymes). Those proteins take food molecules and combine them with oxygen (O2). The mitochondria are the only place in the cell where oxygen can be combined with the food molecules. After the oxygen is added, the material can be digested. They are working organelles that keep the cell full of energy. A mitochondrion may also be involved in controlling the concentration of calcium (Ca) within the cell.

ORGAN SYSTEM-MAJOR ROLES and MAJOR ORGANS

DIGESTIVE
The main role of the digestive system is to breakdown and absorb nutrients that are necessary for growth and maintenance.
Mouth, esophagus, stomach, small and large intestines.
REPRODUCTIVE
The main role of the reproductive system is to manufacture cells that allow reproduction. In the male, sperm are created to inseminate egg cells produced in the female
Female: ovaries, oviducts, uterus, vagina and mammary glands.
Male: testicles, seminal vesicles and pennies.
RESPIRATORY
The main role of the respiratory system is to provide gas exchange between the blood and the environment. Primarily, oxygen is absorbed from the atmosphere into the body and carbon dioxide is expelled from the body.
Nose, trachea and lungs.
CIRCULATORY
The main role of the circulatory system is to transport nutrients, gases (such as oxygen and CO2), hormones and wastes through the body.
Heart, blood vessels and blood.
LYMPHATIC
To destroy and remove invading microbes and viruses from the body. The lymphatic system also removes fat and excess from the blood.
Lymph (fluid), lymph nodes and vessels, white blood cells, T- and B-cells.
EXCRETORY
To filter out cellular wastes, toxins, and excess water or nutrients from the circulatory system.
Kidneys, ureters, bladder and urethra, skin.
NERVOUS
To relay electrical signals through the body. It directs behavior and movement and, along with the endocrine system, controls psychological processes such as digestion, circulation, etc..
Brain, spinal cord and peripheral nerves.
MUSCULAR
The main role of the muscular system is to provide movement. Muscles work in pairs to move limbs and provide the organism with mobility. Muscles also control the movement of materials through some organs, such as the stomach and intestine, and the heart and circulatory system.
Skeletal muscles and smooth muscles throughout the body.
ESKELETAL
The main role of the skeletal system is to provide support for the body, to protect delicate internal organs and to provide attachment sites for the organs.
Bones, cartilage, tendons and ligaments.
ENDOCRINE
To produce hormones that regulates the body's growth, metabolism, and sexual development and function. The hormones are released into the bloodstream and transported to tissues and organs throughout the body.
Ovaries and Testicles, Pancreas, Parathyroid glands, Pineal body, Pituitary Gland, Thymus Gland, Thyroid Gland, Adrenal Glands, Hypothalamus.

INTERNET--- WHAT`S THAT?

Introduction

Unless you never watch TV, listen to a radio, or read, you almost certainly have heard about the Internet or know something about it. Very few people have never heard of the Internet; however most people have either used the Internet occasionally or frequently. It doesn't take much to know that the Internet has attracted an enormous amount of attention the past few years.
That would cause thousands of companies, millions of people and virtually every major country in the world to invest millions of dollars into the Internet? An even better question is what would caused something that operated for nearly 20 years without much public interest to grow to such overwhelming popularity in 6 short years? What truly is all this fuss about?
Some believe it's the speed and wide variety of information found on the net that has made it so popular. Others say it's the ease one can access and publish information on the Internet while others just believe it is a fad. No matter what people say, they can't deny the Internet's tremendous growth rate and current level of popularity in this and other countries.

Who uses it?

In fact, if you have not heard or browsed the Internet, it is not the fault of the Internet. It just isn't that complicated or isolated. Furthermore, anyone with a computer, phone line, modem , and an ISP can connect and even publish on the Internet. However to publish you will have to get to know some Basic Terms such as HTML, HTTP, URL, and others. From young to old, millions of companies, organization, and individuals have published with great success.
ust look around. As my mom says, "Everything has gone www.com crazy." Don't get me wrong the Internet has its complex side. It is a well thought out network with lots of technical languages and protocols that make it work. But that complexity has simply made it easier for the average person to use. From doctors, lawyers, professors, scientist to hobbyist, housewives and elementary students all have found something of value on the Internet .

Its Benefits:

The Internet's speed, vast resources, and its ability to directly communicate with others are its greatest benefits. Because the Internet uses the quickness of computers to transmit its data, information can travel at tremendous speeds. Speed is not the only benefit. The Internet uses hundreds of thousands of computers all connected to each other to store vast amounts of information. And finally, because the Internet allows for individuals to have specific electronic mail addresses, people can easily communicate with one another.
he Internet is considered by many to be superior to the best and biggest libraries in the county. This superiority exists primarily due to the thousands of organizations, companies and individuals publishing on the Internet. With such ease of publishing and the wide variety of publishers, there is almost no subject left off the Internet. The Internet's ability to deliver this vast amount of information has drawn even more users. Not having to wait for a book, newspaper, or magazine publisher to review and send an author's manuscript to a printing press to be bound or printed eliminates the time it would normally take to publish something. Instead of reading a medical breakthrough in next month's journal, it can be published on the Internet instantly. A breaking news event can be published almost immediately after the event occurs. People don't have to wait until the morning paper to read about an event. This part of the Internet alone has helped make the Internet a technological breakthrough.
Even finding not so current information can be a breeze using the Internet. Driving to a library and searching for possibly hours just to find some specific information is a task many of us have experienced. With the Internet you can sit in the convenience of your home and search (surf) to find information faster than going to a library.
Theoretically, the information on the Internet can travel at the speed of light (186,000 miles/sec.). Realistically, we know that this speed is nearly impossible due mainly to the large number of people using the Internet, and the limitation of the phone system. However the Internet's speed is much faster than traditional means of gathering news and reporting information.
Communication is a huge benefit of the Internet. Many people use the Internet to simple send messages and nothing else. Whether it be by news groups, chat rooms, or the most popular method E-mail, communicating over the Internet has developed vast appeal and usage. Millions of people around the globe use E-mail to communicate everyday. They all place great value on the convenience of sending and receiving E-mail. I am one of its biggest fans. E-mail can be sent and retrieved by its recipient almost instantly. The message never has to be printed or physically mailed to get to it's destination. Furthermore, the cost is considerably less than a thirty-two cent stamp and is delivered a lot faster.
With the invention of the Internet phone, some people can now even talk across the Internet just like on a voice phone but without paying long distance charges. It is just a fact; the time it takes to send a letter or reply to a phone message is no match for E-mail's speed and convenience.

How did the Internet begin?

The Internet's history is not very complicated nor that long. It may surprise you to know that the Internet began 25 years ago as an experiment of the U.S. Defense Department. In fact, it was not originally designed for the public's personal use. The original goal of the Internet was to establish a system to safeguard the exchange of information among different government agencies in the event of war. With no one computer or person controlling the Internet, the enemy could not destroy our means of communication with just one military strike. Today this unique feature of the Internet remains constant and part of its success. No one person or organization controls or heads the Internet. It is basically hosted by thousands of individual computers that have registered with the NSF (National Science Foundation) for an Internet address.
In 1991 there were only 100 host computers or sites. Today this number exceeds half a million and is constantly growing. The Internet has certainly seen tremendous growth in just the past 3 to 6 years.
That really caused the Internet's tremendous growth spurt was the invention of something that made the Internet both easy to use and easy to transmit multimedia (graphics, sound, and video). The invention was a software product now known as a browser . In 1991 in an European physics lab, an invention was made that enabled words in a sentence to be clicked on and an action then performed. This invention today is know as hypertext . Hypertext is when words or pictures are clicked on that takes the place of typing commands into the computer. This single feature made the Internet easier to use. With this invention came new users from small kids to senior adults who felt comfortable riding the information super highway. This has forever changed the way average people use the Internet. Today we find people reading magazines, buying products, listening to radio stations, talking to friends, writing messages, playing games, even watching video all through the use of the Internet.

Conclusion

With almost each passing day, a new product or tool is invented or improved upon to help people use the Internet. However millions of people still are not using the Internet. This is due mainly to the lack of either a computer or an Internet service provider. Nevertheless the Internet continues to surprise even the experts with its tremendous growth and popularity. Its tremendous influence on today's society is certain to be felt for many years to come.

HIV!!!!

In the United States, over 600,000 reported cases of AIDS have been recorded since 1981 and it is believed that 900,000 Americans may be infected with HIV. Although development time varies from individual to individual, since 1992 scientists have estimated that roughly half of the people living with HIV will develop AIDS within 10 years of becoming infected. AIDS is growing most rapidly among minority populations, as well as women and injection drug users. According to the U.S. Centers for Disease Control and Prevention, the prevalence of AIDS is six times higher in African-Americans and three times higher among Hispanics than among whites.
AIDS was first reported in the United States in 1981 and HIV was first identified in 1983, however, studies of stored blood samples indicate that HIV first entered the U.S. population in the late 1970s. Recently, there has been an overall stabilization in the emergence of new AIDS cases in the United States, however, worldwide the epidemic continues to rage, particularly in developing countries and the African continent. According to the NIAID, an estimated 30.6 million globally were living with HIV/AIDS as of December 1997 and the figure was projected to reach 40 million by the year 2000 -- more than 75% of adult infections were as a result of heterosexual contact.