Microbiology lecture Chapter 16- Innate immunity- Nonspecific Defenses of the Host
Immunity is _________________.
The ability to ward off disease through body defenses.
Lack of immunity is called _______________.
Innate immunity is ____________.
All the body defenses that protect the body against any kind of pathogen. Not specific - no memory and a quick response.
Adaptive immunity is _________________.
Refers to defenses (antibodies) against specific microorganisms. Involves memory and slower to respnd.
What is the purposeof the innate immune system?
To recognize and destroy pathogens and their products
It does not rely on previous exposure
It is present since birth
largely due to phagocytes- leukocytes
If innate immune system not able to repsond phagocytes will activate the adaptive immune response
Innate defenses are
(all act to destroy pathogens)
Molecular defenses ( these 2 inactivate toxins that have gained entry)
Physical barrier is the _______.
The skin is a physical barrier preventing entry. The skin is inhospitable because its____________.
Most normal microflora is ____________.
hard for gram (-) to survive on surface of the skin because thinner cells walls
The most common microorganism found on the skin is ________________.
Another physical barrier is the ________________.
What type of cells produce mucous on the epithelial layer?
Can it trap microbes?
The cilia moves ______ up and out the _________.
mucous up and out the upper respiratory tract
True or false the lower respiratory system should be sterile.
Other physical factors involve:
lacrimal apparatus: constant washing of the conjunctiva (eye)
Saliva: dilute microbes/ washing teeth
Hair: covered with mucus at the base, function as a filter, traps microbes from entering the LRT
Cilia: ciliary escalator, moves microbes and debris up towards URT, cigarette smoke destroys or paralyzes the cilia
Urine, vaginal secretions, vomiting, defecations and peristalis:
are constantly flushing microbes out of your body
Chemical factors are:
Sebum- helps maintain low pH
Lysozyme: digestive product- that can help destroy microbes and can be found in:
- nasal secretions
Gastric juices (low pH)
Vaginal secretions (low pH)
Antimicrobial substances are _________________.
The complement system that is a collection of proteins produced in the liver and circulate the whole body attacking pathogenic microbes. They trigger inflammation, lysing foreign entities, and improving and enhancing phagocytosis.
If spun in a machine and all the blood separated it would be 58% plasma, 42% RBCs and less than 1% WBCs.
All WBCs are found in the _________________.
Leukocytes in buffy coat:
Neutrophils: highly phagocytic, first to travel to infection site
Eosinophils: phagocytic- produce toxic substance to kill helminths
Monocytes: immature leukocytes at site of infection phagocytic; when they mature they become macrophages in later stage of the infection
Phagocytosis is when _______________________.
When defensive cells travel to site of infection;conducted by WBCs (phagocytes)
Which leukocyte is the first to arrive when there is an infection?
Phagocytosis is activated by ___________, ________, and _____________.
1. Lipid A the toxic portion gram (-) bacteria
2. Lipopolysaccharide: gram (-) bacteria
3. Cytokines (produced by WBCs)
Signal for phagocytosis to begin:
bacteria sending a chemical signal (toxic product)------> wounded tissue ------> Phagocytic cell----> for more phagocytic cells to come help fight the infection
The pseudopodia (false feet) bring foreign entity into the cell to digest in the phagocyte within the phagocyte is a ___________ where the foreign entities can be found.
Phases of phagocytosis:
Chemotaxis: signal- microbes, microbial products, damaged dell tissue, wbcs, and other microbial agents attract phagocytes
Adherence: Attachment of phagocyte to microbe
facilitated if coated with protein (PAMPS)
Ingestion: the pseudopodia extend around the microbe and engulf; microbe within a phagocytic vesicle called a phagosome
lysosome fuse with phagosome (phagolysosome)and release digestive enzymes; undigested material is excreted by cell
Phagocytes have ____ ______ receptors that detect and attach to foreign matter. It is like a lock and key fit.
What does PAMPs stand for?
pathogen associated molecular patterns
What are PAMPs?
anything that is foreign and not part of your body (self)
What is in a lysosomes?
digestive enzymes- lysozine
stomach of the cell
Host cells have toll like receptors that are made of ________ and embedded in the _________.
Microbes have receptors that bind to _________ such as pathogen-associated molecular patterns (PAMPs).
response to tissue damage
What is the purpose of inflammation?
eliminate cause of inflammation
remove microbe, products of microbes (one causing the damage) or keep it localized
repair damaged tissue
Is chronic inflammation acceptable?
No- chronic inflammation is a problem because it will start doing damage to your tissue
Sequence of events in inflammation:
1. Tissue damage
2. Chemical signals released
*vasodilation - increasing blood flow to area
*permeability of blood vessels-more leaky (WBCs)
*recruitment of phagocytic cells
3. Cellular adhesion molecules are altered by cytokines
- that causes margination which the WBCs attaching to the endothelium of blood vessels before they can exit
4. Exit is called immigration
5. Tissue repair: new cells replace damaged ones
The 4 responses of inflammation are:
Redness (erythema): rush of blood to area
Swelling (edema): plasma going to injured tissue
Pain: swelling pushing on pain receptors
The complement system involves ___________ that are produced by the liver and released into the ___________.
proteins- sequentially activated
In the complement system the proteins are designated___________-.
C1, C2, C3......
Activated C3 splits into
C3a and C3b
Function of the complement system:
What is C3b's function?
to coat surface of foreign microbe- its like highlighting or flagging the microbe for the immune system and by doing so makes it easier for phagocytes to attach and digest
know this well
What 3 things are caused by the complement system?
How does the complement system get turned on?
Antigen-antibody complexes bind and activate C1
C1 activates C2 and C4
C2a and C4b ---->C2aC4b
Complement proteins (factors) bind to microbes
Phagocytes signal liver to produce lectins
lectins bind to surface sugars on microbe ----> activates C2 and C4
C2a and C4b -----> C3
Cytokines (chemical signals) do what?
They trigger the liver cells to produce lectins- very specific in for certain molecular fragments microbial in origin
Will lectins bind to our cells normally?
How can bacteria get around our immune system?
M protein- heat/acid resistant protein on cell wall surface and fimbriae of staphylococcus pyogenes
Capsules- don't let phagocytes to attach to microbes
leukocidins and streptolysins- destroy and or rupture WBCs and cells
membrane attack complexes- create holes in phagocytes that cause lysis- release microbes
replication within phagosomes
-due to low pH
some escape before phagolysosome
prevention fusion between phagosome and lysosome