Teacher Training College 2008 - EDI

What are cardiovascular diseases?




C ardiovascular diseases include coronary heart disease (heart attacks), cerebrovascular disease, raised blood pressure (hypertension), peripheral artery disease, rheumatic heart disease, congenital heart disease and heart failure. The major causes of cardiovascular disease are tobacco use, physical inactivity, and an unhealthy diet.

Globally, cardiovascular diseases are the number one cause of death and is projected to remain so. An estimated 17.5 million people died from cardiovascular disease in 2005, representing 30 % of all global deaths. Of these deaths, 7.6 million were due to heart attacks and 5.7 million due to stroke. About 80% of these deaths occurred in low- and middle-income countries. If current trends are allowed to continue, by 2015 an estimated 20 million people will die from cardiovascular disease (mainly from heart attacks and strokes).

What causes heart attacks and strokes?

Heart attacks and strokes are mainly caused by a blockage that prevents blood from flowing to the heart or the brain. The most common cause is a build-up of fatty deposits on the inner walls of the blood vessels that supply the heart or brain. The blood vessels become narrower and less flexible, also known as atherosclerosis (or hardening of the arteries). The blood vessels are then more likely to become blocked by blood clots. When this happens, the blocked vessels cannot supply blood to the heart and brain, which then become damaged.


What are common symptoms of cardiovascular diseases?

• Often, there are no symptoms of the underlying disease of the blood vessels. A heart attack or stroke may be the first warning of underlying disease.
• Symptoms of a heart attack include: pain or discomfort in the centre of the chest; pain or discomfort in the arms, the left shoulder, elbows, jaw, or back. In addition the person may experience difficulty in breathing or shortness of breath; feeling sick or vomiting; feeling light-headed or faint; breaking into a cold sweat; and becoming pale.
• Women are more likely to have shortness of breath, nausea, vomiting, and back or jaw pain.
• The most common symptom of a stroke is sudden weakness of the face, arm, or leg, most often on one side of the body. Other symptoms include sudden onset of: numbness of the face, arm, or leg, especially on one side of the body; confusion, difficulty speaking or understanding speech; difficulty seeing with one or both eyes; difficulty walking, dizziness, loss of balance or coordination; severe headache with no known cause; and fainting or unconsciousness.
• People experiencing these symptoms should seek medical care immediately.

Why does fat build up in blood vessels?

There are three main reasons for fatty build-up, all controllable:
• Smoking and other tobacco use
• Unhealthy diet; and
• Physical inactivity.

An early form of fatty deposits, known as ''fatty streaks'', can even be found in some children younger than 10 years. These deposits get slowly worse as the person gets older.

Key messages to protect heart health:

• Heart attacks and strokes are major - but preventable - killers worldwide.
• Over 80% of cardiovascular disease deaths take place in low-and middle-income countries and occur almost equally in men and women. Cardiovascular risk of women is high particularly after menopause.
• Tobacco use, an unhealthy diet, and physical inactivity increase the risk of heart attacks and strokes.
• Cessation of tobacco use reduces the chance of a heart attack or stroke.
• Engaging in physical activity for at least 30 minutes every day of the week will help to prevent heart attacks and strokes.
• Eating at least five servings of fruit and vegetables a day, and limiting your salt intake to less than one teaspoon a day, also helps to prevent heart attacks and strokes.
• High blood pressure has no symptoms, but can cause a sudden stroke or heart attack. Have your blood pressure checked regularly.
• Diabetes increases the risk of heart attacks and stroke. If you have diabetes control your blood pressure and blood sugar to minimize your risk.
• Being overweight increases the risk of heart attacks and strokes. To maintain an ideal body weight, take regular physical activity and eat a healthy diet.
• Heart attacks and strokes can strike suddenly and can be fatal if assistance is not sought immediately.

"Computer Science is no more about computers than astronomy is about telescopes"

What's the Internet?

"The Internet is transitory, ever changing, reshaping and remolding itself."

The Internet is a worldwide network of thousands of linked computers compared to "a giant international plumbing system" (University of California, Berkeley, 1997). Remember that the Internet is not just one gigantic computer with all of the information; rather there are many computer centers, and we are connected to this "plumbing system" somewhere along the line. There are million of users connected to the Internet, and this figure grows daily. How did the Internet get Started? A long story, but for the purposes of this entry, I'd like you to remember a couple of things: Back in the late 1960s, the U.S. Department of Defense (in an agency called the Defense Advanced Research Projects Agency, or DARPA) came up with the idea of creating of a network of computers as a means of communication in case of some national emergency such as a nuclear war. Thus, if one of these centers was destroyed, the others would still function. This first computer network was called DARPANET, but later was changed to just ARPANET. This idea was a real success, and researchers and educators saw the possibilities of using such networks in their own fields, and created NSFNET (the National Science Foundation NETwork) in the mid-1980s, which linked five supercomputer centers. Today, the ever-growing network of computers around the world is now called the Internet.

"Ask an impertinent question and you're on the way to a pertinent answer"Jacob Bronowski

AIDS is caused by the human immunodeficiency virus (HIV). HIV destroys a type of defense cell in the body called a CD4 helper lymphocyte (pronounced: lim-fuh-site). These lymphocytes are part of the body's immune system, the defense system that fights infectious diseases. But as HIV destroys these lymphocytes, people with the virus begin to get serious infections that they normally wouldn't — that is, they become immune deficient. The name for this condition is acquired immunodeficiency syndrome (AIDS).

As the medical community learns more about how HIV works, they've been able to develop drugs to inhibit it (meaning they interfere with its growth). These drugs have been successful in slowing the progress of the disease, and people with the disease now live much longer. But there is still no cure for HIV and AIDS.

How Does HIV Affect the Body?
A healthy body is equipped with CD4 helper lymphocyte cells (CD4 cells). These cells help the immune system function normally and fight off certain kinds of infections. They do this by acting as messengers to other types of immune system cells, telling them to become active and fight against an invading germ.

HIV attaches to these CD4 cells, infects them, and uses them as a place to multiply. In doing so, the virus destroys the ability of the infected cells to do their job in the immune system. The body then loses the ability to fight many infections.

Because their immune systems are weakened, people who have AIDS are unable to fight off many infections, particularly tuberculosis and other kinds of otherwise rare infections of the lung (such as Pneumocystis carinii pneumonia), the surface covering of the brain (meningitis), or the brain itself (encephalitis). People who have AIDS tend to keep getting sicker, especially if they are not taking antiviral medications properly.

AIDS can affect every body system. The immune defect caused by having too few CD4 cells also permits some cancers that are stimulated by viral illness to occur — some people with AIDS get forms of lymphoma and a rare tumor of blood vessels in the skin called Kaposi's sarcoma. Because AIDS is fatal, it's important that doctors detect HIV infection as early as possible so a person can take medication to delay the onset of AIDS.

About 12 million people in Asia are at risk of being infected with HIV by 2010 unless prevention efforts are intensified.

This is a great spot to raise awareness about the effects of HIV launched in France ... click here

T he endocrine system is a collection of glands that produce hormones that regulate the body's growth, metabolism, and sexual development and function. The hormones are released into the bloodstream and transported to tissues and organs throughout your body.

Ovaries and testicles: Secrete hormones that influence female and male characteristics, respectively.
Pancreas: Secretes a hormone (insulin) that controls the use of glucose by the body.
Parathyroid glands: Secrete a hormone that maintains the calcium level in the blood.
Pineal body: Involved with daily biological cycles.
Pituitary gland: Produces a number of different hormones that influence various other endocrine glands.
Thymus gland: Plays a role in the body's immune system.
Thyroid gland: Produces hormones that stimulate body heat production, bone growth, and the body's metabolism.
Adrenal glands: Divided into 2 regions; secrete hormones that influence the body's metabolism, blood chemicals, and body characteristics, as well as influence the part of the nervous system that is involved in the response and defense against stress.
Hypothalamus:Activates and controls the part of the nervous system that controls involuntary body functions, the hormonal system, and many body functions, such as regulating sleep and stimulating appetite.

"The goal of science is to build better mousetraps. The goal of nature is to build better mice"
Anonymous

M ITOCHONDRIAprovide the energy a cell needs to move, divide, produce secretory products, contract - in short, they are the power centers of the cell. They are about the size of bacteria but may have different shapes depending on the cell type.
Mitochondria are membrane-bound organelles, and like the nucleus have a double membrane. The outer membrane is fairly smooth. But the inner membrane is highly convoluted, forming folds called cristae. The cristae greatly increase the inner membrane's surface area. It is on these cristae that food (sugar) is combined with oxygen to produce ATP - the primary energy source for the cell.

R IBOSOMES: Ribosomes are the large, ribonucleoprotein factories in which proteins are synthesized. In this process, messenger RNA (mRNA) codons are read by the anticodons of adaptor, transfer RNAs (tRNAs) that carry codon-specific amino acids. These amino acids are added to a growing protein chain by peptide bond formation in the heart of the ribosome.
These ribosomes provide the structural site where the mRNA sits. The amino acids for the proteins are carried to the site by "transfer RNAs".


E NDOPLASMIC RETICULUM: Throughout the eucaryotic cell, especially those responsible for the production of hormones and other secretory products, is a vast amount of membrane called the endoplasmic reticulum, or ER for short. The ER membrane is a continuation of the outer nuclear membrane and its function suggests just how complex and organized the eucaryotic cell really is.
When viewed by electron microscopy, some areas of the endoplasmic reticulum look "smooth" (smooth ER) and some appear "rough" (rough ER). The rough ER appears rough due to the presence of ribosomes on the membrane surface. Smooth and Rough ER also have different functions. Smooth ER is important in the synthesis of lipids and membrane proteins. Rough ER is important in the synthesis of other proteins.

Information coded in DNA sequences in the nucleus is transcribed as messenger RNA. Messenger RNA exits the nucleus through small pores to enter the cytoplasm. At the ribosomes on the rough ER, the messenger RNA is translated into proteins. These proteins are then transferred to the Golgi in "transport vesicles" where they are further processed and packaged into lysosomes, peroxisomes, or secretory vesicles.

GOLGI COMLEX: The Golgi apparatus is a membrane-bound structure with a single membrane. It is actually a stack of membrane-bound vesicles that are important in packaging macromolecules for transport elsewhere in the cell. The stack of larger vesicles is surrounded by numerous smaller vesicles containing those packaged macromolecules. The enzymatic or hormonal contents of lysosomes, peroxisomes and secretory vesicles are packaged in membrane-bound vesicles at the periphery of the Golgi apparatus.

LYSOSOMES: Lysosomes (common in animal cells but rare in plant cells) contain hydrolytic enzymes necessary for intracellular digestion. In white blood cells that eat bacteria, lysosome contents are carefully released into the vacuole around the bacteria and serve to kill and digest those bacteria. Uncontrolled release of lysosome contents into the cytoplasm is also a component of necrotic cell death.
S ECRETORY GRANULES: A membrane-bound particle, usually protein, formed in the granular endoplasmic reticulum and the Golgi complex.

"In questions of science,authority of a thousand is not worth the humble reasoning of a single individual"

The cell is the structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. Some organisms, such as most bacteria, are unicellular (consist of a single cell). Other organisms, such as humans, are multicellular. (Humans have an estimated 100 trillion or 1014 cells; a typical cell size is 10 µm; a typical cell mass is 1 nanogram.) The largest known cell is an unfertilized ostrich egg cell.

There are many different cells in the human body. The different cells in the body are generally grouped into tissues that have similar properties. The four main groups of tissues in the body are, muscular, nervous, connective, and epithelial.

WElcome