00:01
Hello everyone, in this question we have been asked to write down all the components of the first line of defense and describe how they protect.
00:09
So there are physical barriers which includes skin, mucous membrane, acidic ph of sweat, the sebaceous secretion and presence of fatty acid as well as hydrolytic enzymes like b12 and the lysozyme and these here work as the and these here inhibit the growth of most of the microorganism.
00:42
So these here work as physical barriers as the first line of defense.
00:46
The tears contain this lysozyme, lactoferrin and also the iga.
00:52
Then there is chemical mediator also.
00:56
So this skin here basically works as a physical barrier.
01:02
It does not allow the microorganisms to enter inside the cell and the mucous membrane here forms the trap due to which it entraps the antigens and so it cannot undergo further damage.
01:19
Then the acidic ph of sweat provides the acidic nature which destroys the antigen.
01:26
So in this way the first line of defense works.
01:30
Then we have been asked to describe all the components of the second line of defense and describe how they protect the body.
01:37
So there are natural killer cells.
01:43
These destroy the cells with intracellular pathogen and they composed of the 5 to 10 percent of the lymphocyte population and they release the perforins as well as granzyme and these are non -specific and they do not recognize the antigen directly and they destroy the malignant and virus infected cells.
02:09
They express cd16 for the fc portion of the immunoglobulin g and then there is dendritic cell which is known as the professional antigen presenting cell.
02:26
So they express the mhc class ii molecules and they acquire the antigen by phagocytosis.
02:34
Antigen is processed and mature dendritic cell present it to the t helper cell.
02:41
Then there are neutrophils which is the first to reach the site of infection and these are present in the case of acute inflammation.
02:56
These have multi -lobed nucleus and stain with both acidic and basic dyes and then there is eosinophils which have bilobed nucleus and these are motile phagocytic cells.
03:15
They have defense against the protozoan and helminth parasite.
03:19
Then there are basophils which have lobed nucleus and these are non -phagocytic and they release the substance that cause the allergic response like the histamine serotonin and they have high affinity for the immunoglobulin e and then there are mast cells which are precursors are formed in bone marrow and these are released into blood and have histamines in large amount.
03:52
There are monocytes also which are mononuclear phagocytic leukocyte and there are macrophages which are phagocytes derived from blood monocytes.
04:06
They have membrane receptors such as the complement receptor fc gamma receptors and these are the antigen presenting cells.
04:17
Then we have the t cells which are t helper cells and t cytosoptic cells which t helper cells basically activates the b cells to mature and then they form into the plasma cell and the memory cell.
04:37
These plasma cell forms the antibody which basically attacks the antigen.
04:44
So, this is how the second line of defense works.
04:48
Then we have been asked below you find a representation of a cytotoxic t cell, helper t cell and b lymphocyte.
04:57
Show that each cell can see and make sure to include in drawing the antigen presenting cell, infected body cell, mhc class 1, mhc class 2, t cell receptor cd4, cd8, igd antitoxicity.
05:13
So, there is mhc class 1 which has 2 alpha chain alpha 1, alpha 2 and here is the n terminal.
05:25
There is alpha 3 which have the disulfide bond attached to it and here we have the c terminal.
05:35
So, this has the b, this has the beta 2 chain which is non -covalently attached and it has the disulfide bond.
05:47
So, this is the structure of mhc class 1...