STPM Countdown to Pengajian Am 2

HIV (Human Immunodeficiency Virus)

One of the scariest virus around is the RNA virus called HIV! Once thought to have originated from Africa is now found worldwide.

What are the symptoms you would have to look out for?
Well, the progress of this disease can be categorized into 4 stages:

1. First Phase: Most individuals will have no symptoms, but some might develop a rash, flu, and swollen lymph glands.
2. Second Phase: Production of anti-HIV rises in blood stream. Although the level of HIV in blood falls, HIV replication continues in lymph nodes. This phase can last anywhere from weeks till more than 13 years.
3. Third Phase: AIDS related complex refers to many opportunistic infections which affect the patient, like fungal and viral infections such as oral and genital herpes.
4. Fourth Phase: Development of secondary cancers. Kaposi's sarcoma and non-Hodgkin's lymphoma are common. By this time, there is total loss of cellular immunity.

Mechanism of HIV Infection:

1. HIV enters the body through body fluid or blood transfusion.
2. HIV binds with CD4 receptors on the surface of T helper cell.
3. Both membranes then fuse while the capsid is enzymatically removed to release viral RNA and reverse transcriptase into the cytoplasm of the helper T cell.
4. Viral RNA undergoes reverse transcription followed by replication to produce a double-stranded viral DNA with the help of enzyme reverse transcriptase.
5. Reverse transcriptase catalyses the synthesis of second DNA, which is complementary to the first.
6. Viral DNA enters the nucleus and is incorporated into host DNA, as a provirus.
7. Provirus may remain dormant but is replicated each time host cell divides.
8. Activated provirus causes host cell to synthesize huge amounts of viral protein and viral mRNA which are then assembled into new retroviruses.
9. New retroviruses bud off from host cell membrane, infecting other helper T cells.
10. Number of helper T cells will gradually decrease and cause risk of individual contacting other diseases and finally leading to death.

Immune Response of Humans.

There are two types of immune response, or rather, what my Bio book tells me so. I was kinda tired of stuffing the facts into my head, so I thought I would type it out here on my iPod Blogger app. :)

Cell-Mediated Immunity:

Cell-Mediated Immune Response

1. T cells formed in the blood marrow circulate in the blood circulatory system until it reaches the thymus glands.
2. In thymus glands, T cells differentiate to form T helper cells and T cytotoxic cells, each with a unique type of T cell receptor on its surface.
3. Mature T helper cell circulates in the blood circulatory system until it reaches an antigen representing cell (APC).
4. If antigen-MHC complex on APC is complementary with the T cell receptor on the T helper cell, the T cell binds to the APC.
5. T helper cell that binds with APC secretes interleukin 1.
6. Interleukin 1 stimulates production of interleukin 2.
7. Interleukin 2 stimulates the division of T helper cells and T cytotoxic cells to produce clones of effector T helper & effector T cytotoxic cells respectively and memory cells.
8. Circulating T cytotoxic cells bind with complementary antigen-MHC complex on infected cells.
9. Effector T cytotoxic cells release perforin that perforated the infected cells to stimulate autolysis.
10. Effector cytotoxic T cells attacks other infected cells, as infected cell perform autolysis.
11. Memory T cells respond for a second invasion of the same pathogen by actively dividing to form effector T cells.

Humoral Immune Response:

1. B cells are formed and mature in bone marrow.
2. Mature B cells synthesize antibodies, which attach to the 2 tips acting as receptors.
3. B cells with complimentary antibody phagocytosise the free complimentary antigens encountered.
4. Antigen is cut into smaller pieces and presented as the antigen-MHC complex on it's plasma membrane.
5. T helper cell with complimentary T cell receptor binds to antigen-MHC complex.
6. T helper cell secretes interleukin 2.
7. Interleukin 2 stimulates B cell to divide and, form clones of effector B cells and memory cells.
8. Effector B cells produce large quantity of free antibodies with same specific configuration.
9. Antibodies destroys antigen by precipitation, antitoxins and agglutination.

Interesting how our immune system works, right?
The only problem is, it's only interesting when you need not memorize it for finals!

Indifferent.

Look at this photo.

All the trays are same in color and in shape. It's a bit like humans if you come to think about it. You and I are the same (in general), we have 2 hands, 2 feet, 2 eyes, 2 ears, etc. But what make us so different?

Thought of the day. :)

Trials will begin as soon as the Raya break is over. This "holiday" didn't seem like one at all.

Anyway, good luck to all those who will be taking their "appetizers" this Tuesday. :D

Go Tigers!

Hitam Kuning! Hitam Kuning! Hitam Kuning! Go Tigers! Go Tigers!

Malaysia will be taking on Singapore tonight, on home ground in Jalan Besar Stadium.

Will the Malaysia be able to score at least 2 goals on advantage?

We shall soon know.

OMK 2011!

Set two different alarms to make sure I woke up for this competition. I had to drag myself out from bed at 6 just to get to school and be on time to board the bus to UNIMAP, Perlis. It seems that Kedah and Perlis hopefuls were scheduled to sit the OMK papers together.

I'm sure you would be in the dark what is OMK all about, if you have never heard of OMK before. Well, OMK stands for Olimpiad Matematik Kebangsaan, a mathematics competition, which is held annually, to select Malaysia's Maths champion to represent Malaysia in the World Mathematics Olympiad. My form, had 5 representatives, all guys, 3 from my class. :D

Students all around Perlis and Kedah met at the centre an hour before the test started, as required. Kolej Sultan Abdul Hamid also sent representatives with at least 8 from Form 6. I happened to know a few of them who came. :D

Sitting for OMK is something new for me. I've not sat for this competition before. It was rather a urmmm... not much of a new experience. Sharing a little about the test... The competition lasts for 2.5 hours. There are 9 questions in this competition. 6 questions requires just the answer, while the remaining 3 requires you to show the working for the solution. The 6 front questions, if answered correctly, will be awarded 2 marks each, while the behind 3 questions if answered correctly with the correct steps will be awarded 6 marks each. And I must say, the questions are not easy!

Can you imagine that the OMK questions had mistakes? Not minor errors, but a MAJOR error! Halfway through the competition, they asked us to change one of the question's positive sign to a negative sign. Such errors shouldn't be made in the first place! Isn't this a Kebangsaan competition?!? What happened to the checking and double-checking of the questions?

Overall, I know I stand no chance in this competition, they others are just too good. I didn't know how to do quite a number of questions. This just shows how weak I am in Mathematics. :( One of my junior, could answer all (except for one question, which he wasn't quite sure of). I guess he will be the champion for this district. :D Keat Hwa boleh!

Anyway, it was fun! I quite enjoyed myself. :D

Holidays are Over!

It's JUNE already. Time flies!

In about less than 72 hours from now, I'll be dragging myself out from bed, staggering to the bathroom, taking a quick shower, crawling into the same school uniform I've been wearing since I was 13.

School is reopening!
"So what?"

*ponders more*
"Crap! Mid-term exam results are coming out!"
"Sunday got Chem, Bio and Maths!"

Oh well, I know for a fact, that only recently, I've been trying to actually WORK HARD, for once. I've never actually wanted something so badly before. I need to work harder to achieve 4.0! I've got to take this exam's result as a lesson to strive harder. :D

A whole load of events are awaiting me in school. Sport's Sukan Tara, Sport's Day, Keat Hwa's 100 year anniversary, Form Six Society Interviews, Form Six Night, etc. It's going to be a real busy time in school. I hope I will be able to manage my time properly. Distractions, SHOO! :D

STPM is coming! I wonder how the teachers are going to finish another volume of Biology and almost the entire Paper 2 for Maths. I mean, there are at least another 14 chapters for Biology alone! And the next question is, how am I going to stuff everything into my head! GAH!

Oh well. Life has it's tough and easy times. I'm having a good life. :)

What is there to complain about? :)

Appreciate what you have today. Everything you have today, might just be taken away from you. Who knows? :)