Immune system
new words
pathogen: 病原体 a disease causing virus or organism
elicit：引出
definition
()
Innate immunity
从你出生之后就没怎么变过 它的组成部分攻击所有病原体
也存在于不含特异性免疫的动物中
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external defenses(the first line of defense)
It prevent your body from infection! not fight after it!
the body has physical barriers including:
a tough outer skin layer which is impenetrable to viruses and bacteria
mucous membrane covered with sticky mucus
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wax in the ear canal which traps incoming things
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antimicrobial secretion(chemical barriers:sweat tears saliva contain enzyme that disrupt bacterial cell walls. eg: strong stomach acid/oil on you skin
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internal defenses( body's second line of defense)
主要依靠两种物质：白细胞和defensive蛋白
1. white blood cells
其中白细胞有两种
- phagocytic cells(phagocytes)/吞噬细胞
which engulf吞噬 foreign cells外来细胞 or molecules and
debris残体 from dead cells- natural killer (NK) cells
which recognize识别 virus-infected and cancerous cells被病毒感染的细胞, when contact is made, release chemicals that kill diseased cells.释放杀死感染细胞的化学物质
2. defensive proteins
some defensive proteins prevent viral reproduction within body cells.
some destroy pathogens directly
others trigger the inflammatory response炎症反应
- 炎症反应 to injury and infection 是一种internal innate defense的例子
步骤有三
- injured cells release chemicals that trigger various internal defenses one such chemical signal histamine
- this substance causes nearby blood vessels to dilate变宽 and leak fluid into wounded tissue 这个过程叫Swelling 肿大。 excess fluid heals流出的液体修复组织 damaged tissue by diluting toxins in it, bring extra oxygen, deliver platelets and clotting proteins to it that promote scabbing.通过稀释该部位的有毒物质（引起反应的），增加氧气（杀死厌氧细菌），输送血小板和clotting蛋白质加快结痂过程。这些化学信号同时也吸引了吞噬细胞
- 吞噬细胞吞噬细菌和细胞残体。伤口处的脓中含有吞噬细胞，毛细管中渗出的液体，以及其他组织残体
不仅如此 受伤的细胞释放的化学信号还会增加伤口附近的血流量 导致伤口附近变红，温度升高
如果受伤严重 还会有其他种类的化学信号通过血液到达大脑，导致发烧的症状，从而抑制伤口附近的细菌活性与繁殖。
消炎药减弱炎症反应，减轻肿大和发烧的症状。消肿可以通过抑制血管变宽。
以上都是innate defense为他们一直处于ready状态无需准备，打击的范围也很广泛。基本上病原体都过不了这一关，能过的了的都需要第三道防线进行点对点打击：）
在学习adaptive defense之前 先了解一下淋巴系统！
Lymphatic system
consist of a branching network of vessels, numerous lymph nodes淋巴结（little round organs packed with white blood cells!） and some other organs including spleen脾 appendix阑尾 and tonsils扁桃体.
淋巴管：carry lymph（淋巴） 细胞外液循环的一部分
淋巴系统的两个主要功能就是：
1.return tissue fluid to the circulatory system
血浆中的物质除大分子蛋白质外，都可以透过毛细血管壁进入组织细胞间隙形成组织液。绝大部分的组织液还可以重新通过毛细血管壁渗透回血浆中，少部分(约10％)则进入毛细淋巴管形成淋巴，淋巴经淋巴循环又进入血管成为血浆。细胞外液与细胞内液通过细胞膜进行物质交换。
淋巴最终进入循环系统通过两个大的位于肩膀且与静脉相通的淋巴管。
如果部分体液未能进入淋巴管那么组织会肿。
2.immune function(fight infection)
淋巴可以carry病原体，在循环过程中吞噬细胞就会把这些病菌吞掉。淋巴结是特定白细胞lymphocytes（淋巴细胞）在infection期间增殖的地点，导致淋巴结肿大。增殖对于adaptive defense十分重要。
Adaptive defenses
(Third line of immune system)
主要靠两种淋巴细胞，它们可以识别、反应一些specific入侵病原体。
像所有血细胞一样，淋巴细胞由骨髓干细胞分化而来。
- B cells
能够识别能够结合 在血液里自由
在骨髓中发育成熟 - T cells
没法识别 必须有helper t cell 告诉killer t cell？？
由血液运输到胸腺中成熟
成熟之后它们都会去淋巴结和其他淋巴器官等待敌人出现哈哈哈。
- antigen 抗原
most of them are on the surfaces of the virus
any given pathogen will have many different antigens on its surface.
also include toxins secreted from bacteria, molecules from mold spores,pollen,dust. molecules on surface of transplanted tissue.
Step 1 recognizing the invaders
B和T的识别机制不同
B细胞
T细胞
B T cells develop antigen receptors on their surfaces
all the receptors on a particular cell matches a specific antigen
and with great amount of B and T cells, their are enough recepters to bind with every possible antigen
B bind with antigen --> short lived cell --> antibody抗体
- antibody 抗体
- Y shaped 4 polypeptides form one
- combine with an antigen to form an antigen-antibody
complex then phagocytosis 自身吞噬细胞把这个复合物吞掉
immune disorder
免疫过分敏感
- 过敏反应 allergery
Allergens are antigens that cause allergies. - 自身免疫
- lupus狼疮
- insulin-dependent diabetes
- multiple sclerosis 多发性硬化症
- rheumatoid arthritis 类风湿性关节炎
免疫作用不足
- inborn condition
- drugs radiation
- acquired illness
AIDS
HIV, virus that causes AIDS. RNA逆转录病毒 attacks helper T cell
Lymphatic System
a network of vessels, tissues, and organs where pathogens and cells involved in innate immunity and adaptive immunity interact with each other to carry out defensive actions.
