Lecture 2 Cellulitis / complementary system Flashcards
(42 cards)
In terms of bacteria size, it can sometimes migrate into the sweat gland. This happens all the time; however, we tend to not get infected all the time. Why is this the case?
Because not all bacteria can survive under human conditions or affect human skin.
- To effect the epithelial cells it has to be the correct type of bacteria.
what type of bacteria can affect the human skin?
The 2 types of bacteria that causes skin infection is S. pyogenes and S. aureus.
how can S.pyogenes damage the cells?
S.pyogenes interacting with the epithelial cells in the sweat glands. It damages the cells by releasing bacterial Toxins called cycolysins.
After damage, what is the first line of defence?
The first line of defence is the macrophages and the dentretic cells. Cells near by marocphages and dendretic cells that eat all the debris and infection. These cells will wonder off and communicate with helper T-cells.
what are the main types of chemical released when damage has occurred?
- IL-8 is a very potent attracter of neutrophils
- IL-1 are a very potent attracter of T-cells and macophages / dentretics cells.
In response to the chemical being released:
Endothelial cells part of the blood vessel increase there receptors, and these receptors are P-selectin and CAM. They are sticky receptors. The concentration of the receptors are higher when they are closest to the chemicals being released. The concentration gradient of receptor decreases as you move further away in the vessels.
how are neutrophils transported to the site of infection?
The receptors on the endothelial cells attract the neutrophils. The neutrophil are more likely to stick and attract to where the CAM adhesion molecules are highly concentrated. This is celled chemoatttraction.
what happens when the endothelial cells open up?
The opening of endothelial cells enables the neutrophil to leak out to the area of damage. The neutraphils travel via chemoattractions to the chemicals released by the epithelium. Specifically attracting to IL-8
why are neutrophils important?
The netrophills are the main immune cells that are recruited earlier during the infection to come along and phagocytose bacteria
what are the function of macrophages and dendritic cells ?
The macrophages and dendretics cells take what they have eaten and present it to helper T-cells
what is the function of Neutrophils?
The Neutrophils main task is to eat the bacteria and kill it.
This process if happening in the space of hours.
When do symptoms occur?
Once, the cells are damaged, that it a sign of when symptoms starts to occur.
Define Diapedis.
- Diapedis is defined as the way neutrophil change the cellular shape and squeeze through the endothelial space.
what are the 3 triggers of the complementary system?
- The largest trigger is the antibody
- The second trigger is from the recognition of human carbonhydrates and carbonhydrates that bacteria consist.
- he third trigger is by complements spontaneously forming on cells surfaces.
what is the complementary system?
- The complement system is doing stuff that augment the immune response (via chemical release at epithelial cells)
- It’s job is to amplify the normal immune response
- It triggers the complement pathway and there are 3 triggers. All these trigger come together to enhance the normal immune response.
describe the trigger of antibodies associated to the complementary system.
The largest trigger is the antibody. When the antibody recognizes and bind to the bacterial antigen. This is an intense trigger for the complement system to kick in.
describe the trigger of recognition of human carbohydrates associated to the complementary system.
The second trigger is from the recognition of human carbonhydrates and carbonhydrates that bacteria consist. One of the carbonhydates is called mannose. The is a protein made from out livers that circulate around allows mannose to bind on to and this protein is called Lectin. This is a good trigger for the complementry system. These bacterial sugars are also recognised by our immune cells, epithelial cells, and endothelial cells. Recognised by things like the Toll like receptor
describe the trigger of spontaneous complement associated to the complementary system.
The third trigger is by complements spontaneously forming on cells surfaces. If that happens on human cells, there are things on our cells to turn it off. But if it happens on a bacterial cell, the complementary casecade is continuous until the bacteria is killed
what is the function of C3 in the complementary mechanism?
- The 3 tirggers wants to form C3 covertase
- C3 convertase is an enzyme
- Its function is to convert C3
The enzyme C3 convertase converts complement C3 → C3a and C3b.
- C3b is important
- A human cannot live without C3b
why is C3b important?
C3b is a very important opsonin that has an essential acitivity to tag bacteria. The reason why this is important is because of its function. It has the ability to coat the antigen or bacteria with antibodies and complementry protein. This coating allows for the enhancement of immune cells like neutrophils, dendretics, and macrophages to recognise the antigen/bacteria and phagocytose it.
What is the function of C3a?
C3a helps blood vessels to open up and improve the delivery od neutrophils to the infection site.
Which C protein has the same function as C3a?
C5a helps blood vessels to open up as well
Some of the C3b binds to the C3 convertase and convert further to form C5 Covertase. what is the function of C5 convertase?
C5 cleaves and converts further to C5a and C5b.
why is C5a important?
C5a is a chemotactic protein along with IL-8.They attract Neutrophils
