1st n 2nd line of defenses (2 Viewers)

[etoile rouge]

Someone please explain difference between 2nd line of defense and the third. Does phagocytotis happen in both? And plz explain the B and T cell stuff.

 

[_blank]

And plz explain the B and T cell stuff.

Can you be more specific about what you don't understand?

 

[k02033]

First:

Skin - skin cells bond tightly together to form a physical barrier to prevent the entry of pathogens. if the skin is broken, blood clots to reseal the opening. the surface of the skin is dry and also contain bacteria and acids that prevents pathogens from mutiplying.

Mucous membranes - mucous membranes are found in the lining of the respiratory, digestive, reproductive and urinary ducts. they produce a sticky fluid known as mucous, which traps pathogens preventing them from reaching organs. mucus can contain antibodies which kill pathogens.

Cilia - cilia are fine hairs found in the lining of the respiratory surfaces. these hairs sweeps the mucous into the throat or nose passage. From the throat, the mucous may be coughed or sneezed out, or swallowed into the stomach where acids destroys the mucois. this removes any pathogens trapped in the mucous, preventing disease.

Chemical barriers - HCL acid found in the stomach and alkaline environment in the small intestines provide pH levels that prevents the growth of pathogens. lysozyme in tears dissolves cell membranes of pathogens.

Other body secretions - some mircoflora acts on the dead cells in the vagina to create acidic conditions that prevents the growth of pathogens. urine is slightly acidic hence kills pathogens in the excretory system when urine is released.

saliva washes bacteria found between the teeth.


Second:

Inflammation occurs when damaged tissues release histamine to allow blood vessels around the infected area to dilate and to become more permeable. this allows more blood and white blood cells to enter the infected area to fight off pathogens. this causes the redness and sore.

Phagocytosis is performed by specialised white blood cells known as phagocytes. these white blood cells are able to remove foreign bodies and thus fight infections. it does this by engulfing foreign objects and destroying them with enzymes called lysozymes.

the lymph system returns intercellular fluids back into the blood stream. the system filters cell debris and produces white blood cells (lymphocytes, third line of defence) that combat infections.

cell death to seal off pathogen, the process where white blood cells excrete nitric acid to kill nearby cells in an infected area, creating a wall of dead cells (cyst) around the pathogen, isolating it from its food supply. in time the pathogen involved dies, and disease is prevented.

Third:

antibodies are glycoproteins produced by the body's plasma cells that aids in removing antigens. each type of antibodies are highly specific to its own target antigen.
antibodies carries out its task by:

1. dissolving cell walls or membranes
2. neutralising toxins excreted by the antigen
3. binding to the antigen's active site so it has no effect on the body
4. binding to and cumping antigen together to make them more susceptible to phagocytosis and the lymph system

B cells are lymphocytes made by the bone marrows. B cells are activated by cytokine secreted by T helper cells. The activated B cell differentiates into either plasma cells that produces antibodies, or into memory cells that remains in the body and are able to quickly fights off subsequent attacks by previously encountered pathogens.

T cells are lymphocytes made by the bone marrow by matures in the thymus gland. there are four types of T cells

1. helper T cells that help to identify the antigen and to stimulate activities of other T cells, B cells and phagocytes
2. memory T cells that remains in the body able to quickly fights off subsequent attacks by previously encountered pathogens by transforming in killer T cells quickly on exposure.
3. killer T cells that secret toxins that directly destroy and prevent any further growth of antigens
4. suppressor T cells that supresses the antibody production after the antigen has be removed.


the interaction between T cells and B cells allows the production of antibodies. this interaction comes about by 2 mechanisms.
1. T cells produces a soluable factor (cytokine) after interaction with an antigen. B cells that comes in contact with this soluable factor begins to differentiate into plasma cells that produces antibodies.
2. direct cellular contact between the T cells and B cells once again triggers the antibody production response.

 

[etoile rouge]

wow, thanx k02033!

 

[k02033]

np

 

[bouncing]

First:

Skin - skin cells bond tightly together to form a physical barrier to prevent the entry of pathogens. if the skin is broken, blood clots to reseal the opening. the surface of the skin is dry and also contain bacteria and acids that prevents pathogens from mutiplying.

Mucous membranes - mucous membranes are found in the lining of the respiratory, digestive, reproductive and urinary ducts. they produce a sticky fluid known as mucous, which traps pathogens preventing them from reaching organs. mucus can contain antibodies which kill pathogens.

Cilia - cilia are fine hairs found in the lining of the respiratory surfaces. these hairs sweeps the mucous into the throat or nose passage. From the throat, the mucous may be coughed or sneezed out, or swallowed into the stomach where acids destroys the mucois. this removes any pathogens trapped in the mucous, preventing disease.

Chemical barriers - HCL acid found in the stomach and alkaline environment in the small intestines provide pH levels that prevents the growth of pathogens. lysozyme in tears dissolves cell membranes of pathogens.

Other body secretions - some mircoflora acts on the dead cells in the vagina to create acidic conditions that prevents the growth of pathogens. urine is slightly acidic hence kills pathogens in the excretory system when urine is released.

saliva washes bacteria found between the teeth.


Second:

Inflammation occurs when damaged tissues release histamine to allow blood vessels around the infected area to dilate and to become more permeable. this allows more blood and white blood cells to enter the infected area to fight off pathogens. this causes the redness and sore.

Phagocytosis is performed by specialised white blood cells known as phagocytes. these white blood cells are able to remove foreign bodies and thus fight infections. it does this by engulfing foreign objects and destroying them with enzymes called lysozymes.

the lymph system returns intercellular fluids back into the blood stream. the system filters cell debris and produces white blood cells (lymphocytes, third line of defence) that combat infections.

cell death to seal off pathogen, the process where white blood cells excrete nitric acid to kill nearby cells in an infected area, creating a wall of dead cells (cyst) around the pathogen, isolating it from its food supply. in time the pathogen involved dies, and disease is prevented.

Third:

antibodies are glycoproteins produced by the body's plasma cells that aids in removing antigens. each type of antibodies are highly specific to its own target antigen.
antibodies carries out its task by:

1. dissolving cell walls or membranes
2. neutralising toxins excreted by the antigen
3. binding to the antigen's active site so it has no effect on the body
4. binding to and cumping antigen together to make them more susceptible to phagocytosis and the lymph system

B cells are lymphocytes made by the bone marrows. B cells are activated by cytokine secreted by T helper cells. The activated B cell differentiates into either plasma cells that produces antibodies, or into memory cells that remains in the body and are able to quickly fights off subsequent attacks by previously encountered pathogens.

T cells are lymphocytes made by the bone marrow by matures in the thymus gland. there are four types of T cells

1. helper T cells that help to identify the antigen and to stimulate activities of other T cells, B cells and phagocytes
2. memory T cells that remains in the body able to quickly fights off subsequent attacks by previously encountered pathogens by transforming in killer T cells quickly on exposure.
3. killer T cells that secret toxins that directly destroy and prevent any further growth of antigens
4. suppressor T cells that supresses the antibody production after the antigen has be removed.


the interaction between T cells and B cells allows the production of antibodies. this interaction comes about by 2 mechanisms.
1. T cells produces a soluable factor (cytokine) after interaction with an antigen. B cells that comes in contact with this soluable factor begins to differentiate into plasma cells that produces antibodies.
2. direct cellular contact between the T cells and B cells once again triggers the antibody production response.

+1!!!!

nice that was really helpful

 

[bio_nut]

You don't need that much detail for a band 6 in bio though.

 

[k02033]

You don't need that much detail for a band 6 in bio though.

Sure you do! In the case that the 8 marker asks you to talk about the lines of defenses. In fact this was a strategy i used in hsc. I pretended that most dot points had a 8 marker question in the test, and answered the dot points correspondingly.

If you are wondering why there are plenty of grammatical mistakes in my notes, that's because i stink in english and i did my hsc notes using notepad (much faster than word).

 

[bio_nut]

Oh, it can help, but it's definitely not necessary.

You do NOT need that much to get those eight marks. I feel sorry for those people who write so, so much when they only need half the amount. They still do it at uni when it's not necessary, lol.

Of course, if you have a good memory, you may as well, but for the majority of people sitting the HSC I'd say that's a bit too much info for one area!

That's just from my experience in HSC Bio and as a tutor.

 

[k02033]

It also allows you to adapt to all sort of questions (no pun intended) simply because you have written so much, so less surprises during the exams.

 

[thongetsu]

quality over quantity

 

[bio_nut]

I'm sorry, but I still don't agree.

It's ok, the students I tutor and I got band 6s, guess there's more than one way to get a band six!

It's the practising of questions to apply the knowledge necessary that is important. Application of knowledge. That is what the HSC Bio is about, I don't think students should just rote learn as much material as possible "just in case". In won't help when they're confronted with an unusual question.

First year science at uni was all about that too, and that's why so many kids who just rote learned everything in the HSC failed miserably.

 

[bio_nut]

quality over quantity

Agreed.

 

[k02033]

I'm sorry, but I still don't agree.

thats cool, everyone has a different way of studying

It's the practising of questions to apply the knowledge necessary that is important. Application of knowledge. That is what the HSC Bio is about, I don't think students should just rote learn as much material as possible "just in case". In won't help when they're confronted with an unusual question.

This sounds like you are trying to imply that writing lots as your syllabus answers trying to prepare for exams constitutes as rote learning, now clearly this is not true.

First year science at uni was all about that too, and that's why so many kids who just rote learned everything in the HSC failed miserably.

Agreed, although not on the levels of passing, but rather grasping the subject and succeeding in the field. I.e. it is entirely possible to pass bio with rote learning.

 

[bio_nut]

No, I think learning unnecessary information when you should be able to work it out with the required knowledge encourages rote learning.

Most students have 4 or 5 other subjects to worry about, so I teach them to apply the knowledge they need to a range of situations, not learn extra info which takes up time that could be spend learning other subjects.

Concise is the way I answer questions and it's serving me well.

Shrug.

 

[thongetsu]

yay for concision!

EDIT: Just know key points and elaborate using key words.

 

[k02033]

No, I think learning unnecessary information when you should be able to work it out with the required knowledge encourages rote learning.

I dont think what you said fits with the definition of rote learning....

Rote learning - Wikipedia, the free encyclopedia

From what i understand rote learning=doing the bare minimum to pass.

Suppose a students spends effort and time to study extra biological facts that is not required to "work it out" in the HSC, and therefore the student is learning "unnecessary info", from my point of view, this act does not encourage rote learning in anyway, if we look at its definition.

Most students have 4 or 5 other subjects to worry about, so I teach them to apply the knowledge they need to a range of situations, not learn extra info which takes up time that could be spend learning other subjects.

Concise is the way I answer questions and it's serving me well.

Shrug.

That is a reflection of your own personal study preference/ strategy. So the correct verb to use in place of "teach" should be suggest.

 

[k02033]

thongetsu may i ask why are you not banned because of your dp?

 

[thongetsu]

because i'm epic

 

[k02033]

Guess i should have asked the moderators, not you.