Tuberculosis (T.B)

Tuberculosis (TB) is an infectious disease that is caused by a bacterium called Mycobacterium tuberculosis. TB primarily affects the lungs, but it can also affect organs in the central nervous system, lymphatic system, and circulatory system among others. The disease was called "consumption" in the past because of the way it would consume from within anyone who became infected. According to Medilexicon`s medical dictionary, tuberculosis is "A specific disease caused by infection with Mycobacterium tuberculosis, the tubercle bacillus, which can affect almost any tissue or organ of the body, the most common site of the disease being the lungs."

When a person becomes infected with tuberculosis, the bacteria in the lungs multiply and cause pneumonia along with chest pain, coughing up blood, and a prolonged cough. In addition, lymph nodes near the heart and lungs become enlarged. As the TB tries to spread to other parts of the body, it is often interrupted by the body's immune system. The immune system forms scar tissue or fibrosis around the TB bacteria, and this helps fight the infection and prevents the disease from spreading throughout the body and to other people. If the body's immune system is unable to fight TB or if the bacteria breaks through the scar tissue, the disease returns to an active state with pneumonia and damage to kidneys, bones, and the meninges that line the spinal cord and brain.

TB is generally classified as being either latent or active. Latent TB occurs when the bacteria are present in the body, but this state is inactive and presents no symptoms. Latent TB is also not contagious. Active TB is contagious and is the condition that can make you sick with symptoms.

JAUNDICE

Jaundice, is a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae (whites of the eyes), and other mucous membranes caused by hyperbilirubinemia (increased levels of bilirubin in the blood). This hyperbilirubinemia subsequently causes increased levels of bilirubin in the extracellular fluids. Typically, the concentration of bilirubin in the plasma must exceed 1.5 mg/dL ( > 35 micromoles/L), three times the usual value of approximately 0.5 mg/dL, for the coloration to be easily visible. Jaundice comes from the French word jaune, meaning yellow.

One of the first tissues to change color as bilirubin levels rise in jaundice is the conjunctiva of the eye, a condition sometimes referred to as scleral icterus. However, the sclera themselves are not "icteric" (stained with bile pigment) but rather the conjunctival membranes that overlie them. The yellowing of the "white of the eye" is thus more properly conjunctival icterus

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@khuhro
what are the source of these posts???or you sharing your own notes???

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these are printed notes, which i have downloaded and edited by during my 2011 attempt (probably year ago i had download them), however, right now dint remeber source of this post...

i will try my best to share my knowledge with other members

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ACID RAIN

"Acid rain" is a broad term referring to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors, or chemical forerunners, of acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) resulting from fossil fuel combustion. In the United States, roughly 2/3 of all SO2 and 1/4 of all NOx come from electric power generation that relies on burning fossil fuels, like coal. Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. The result is a mild solution of sulfuric acid and nitric acid. When sulfur dioxide and nitrogen oxides are released from power plants and other sources, prevailing winds blow these compounds across state and national borders, sometimes over hundreds of miles.

Wet Deposition
Wet deposition refers to acidic rain, fog, and snow. If the acid chemicals in the air are blown into areas where the weather is wet, the acids can fall to the ground in the form of rain, snow, fog, or mist. As this acidic water flows over and through the ground, it affects a variety of plants and animals. The strength of the effects depends on several factors, including how acidic the water is; the chemistry and buffering capacity of the soils involved; and the types of fish, trees, and other living things that rely on the water.

Dry Deposition
In areas where the weather is dry, the acid chemicals may become incorporated into dust or smoke and fall to the ground through dry deposition, sticking to the ground, buildings, homes, cars, and trees. Dry deposited gases and particles can be washed from these surfaces by rainstorms, leading to increased runoff. This runoff water makes the resulting mixture more acidic. About half of the acidity in the atmosphere falls back to earth through dry deposition.

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Climate Change

What is Climate Change
Our planet is surrounded by a blanket of gases which keeps the surface of the earth warm and able to sustain life. This blanket is getting thicker, trapping in heat as we release greenhouse gases by burning fossil fuels for energy.

By trapping more of the sun’s heat the earth’s temperature is starting to rise. This phenomenon is known as Global Warming.

Scientific research indicates that, because of climate change, we may experience more intense and more frequent extreme weather events.

The gradual increase in temperature has major implications for ecosystems, growing seasons, animals and their delicate habitats.

In just 200 years, the amount of carbon dioxide in the atmosphere – the major gas that causes climate change – has increased by 30 per cent.

Concentrations of greenhouse gases are now higher than at any point in the past 800,000 years with an average near-surface global temperatures rise of 0.7°C over the past 100 years.

The Intergovernmental Panel on Climate Change indicated that, if we could get greenhouse gas emissions to peak and then decline within the next 10–20 years, the risk of seeing temperature changes higher than 2° C would be greatly reduced.

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Biodiversity


Biodiversity is the variety of species, their genetic make-up, and the natural communities in which they occur. It includes all of the native plants and animals in Pennsylvania and the processes that sustain life on Earth. Pennsylvania is home to over 25,000 different species of organisms, and of this total, over 800 are considered to be rare, threatened, or endangered. For many groups of organisms, such as insects, fungi, and algae, very little is known about them - not even what species occur in Pennsylvania! The need to understand the state's rich natural resources has never been more critical.

The term ecosystem is defined as a community of living organisms combined with their associated physical environment. It is our "home system" that makes life possible. Ecosystems are the full tapestry of nature that support life and they also provide valuable services.

• Wetland ecosystems filter out toxins, clean the water, and control floods.
• Estuaries act as marine-life nurseries.
• Forest ecosystems supply fresh water, provide oxygen, control erosion, and remove carbon from the atmosphere.

Many species, working together, are needed to provide these critical services. The loss of biodiversity reduces nature's ability to perform these functions. As greater fluctuations occur, ecosystems as a whole become less stable. Instability causes ecosystems to be more vulnerable to extreme conditions and may also decrease productivity.

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Tsunami

The word tsunami (pronounced soo-NAH-mee) is Japanese, and it means ‘harbour wave’.

A tsunami is a huge volume of moving seawater. These giant waves can travel for thousands of miles across the sea and still have enough energy and force to destroy buildings, trees, wildlife and people.

If you throw a stone in a pond it will create a series of ripples. A tsunami is just like those ripples but the disturbance that sets them moving is much greater than a small stone. It can be triggered by an undersea earthquake, landslide or volcanic eruption.

In deep water tsunami waves can extend thousands of feet into the sea, and reach speeds of 500mph, almost fast enough to keep up with a jet airplane. There can be up to a hundred miles between each wave, which may be just a few feet above the sea.
Most Tsunamis are caused by undersea earthquakes. These underwater earthquakes cause disruption to the seafloor and, in turn, the overlying water. A tsunami and has nothing to do with tides although it is sometimes mistakenly called a tidal wave.

How and where do these undersea earthquakes occur?

The earth is made up of several pieces of hard rock that fit together a bit like a jigsaw. These are called tectonic plates and they move very slowly. Oceanic plates are denser/heavier than continental plates and so they slide under the continental plates. Where this happens it is called a subduction zone. There are subduction zones off Chile, Nicaragua, Mexico and Indonesia. These areas are prone to earthquakes, which happen when the plates suddenly move against each other.

What other things could create a tsunami?

Sometimes when an ocean island collapses it causes a huge displacement of water which can also create a tsunami. Very rarely, a tsunami can be created by a giant meteor hitting the sea!

Scientists found traces of a huge meteor rock that collided with the Earth 3.5 billion years ago and landed in the sea, which may have created a giant tsunami that drastically changed coastlines and wiped out almost all life on land.

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Lahar

A lahar is a slurry of volcanic material and water. Despite the fact that lahars can be very thick, like concrete, they can move incredibly quickly, and they are often deadly. Because a lahar can occur on a volcano which is not actively erupting, it is a significant risk, since one may occur with minimal warning. Geologists have studied lahars in an attempt to be able to predict their path so that people can evacuate to safety quickly when it becomes apparent that a lahar is happening.

The word is borrowed from the Javanese language used in Indonesia. In Javanese, lahar means lava, or lava flow, and geologists adopted the term to refer specifically to flows of volcanic rock and water. In some regions of the world, the term “lahar” also refers to a dry landslide of volcanic material, which can be no less deadly. A lahar will always flow down slope, following the path of least resistance, which makes predicting the paths of potential lahars much easier.

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Invertebrate

An invertebrate is basically an animal that is lacking a vertical support system in their structural makeup, for example a backbone or notochord. Almost all of the earths living animal species are filed under the invertebrate distinction. Only 3% of the living animals that travel the vast earth are considered vertebrates. They fall under the Chordate subphylum of Vertebrata. Vertebrates most commonly include mammals, birds, reptilians, fish species, and also amphibians. Invertebrates encompass over 30 phyla (phylums, greek for clans) and range from the basic sea cucumber through flatworms, mollusks, corals, and even include arthropods like crabs. Invertebrates are found on land and in sea and if it is a living animal and it is not a reptile, amphibian, mammal, bird, or fish it is very highly likely it is an invertebrate.

Other common underwater animals that fall under invertebrate are flatworms, crustaceans, bryozoa, jellyfish, snails, sponges, coral, worms, squid, starfish, sea urchins, hydras, anemones, lobsters, crabs, sea barnacles, brittle stars, octopus, ribbon worms, shrimp, lobsters, crayfish, sand dollars, and many more species

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