Non-specific immune review Flashcards
3 defining characteristics about the innate immune system
1) Present @ birth
2) Always at work
3) In place before exposure to a pathogen
what are the 4 parts of innate defence
1) Physical barriers (1st line)
2) Cellular defence (2nd line)
3) Chemical defence (2nd line)
4) Inflammation
What are the physical barriers
Skin & mucous membranes.
what are the 2 things that epithelial membranes do
1) physical barrier
2) produce secretions
what are the antimicrobial secretions
1) Acid
2) enzymes
3) Mucus
4) Defensins
5) Dermcidin
What does acid do & where does it come from
Skin, Vagina, Stomach. Low pH inhibits bacterial growth.
what do the enzymes do and where do they come from
Lysozyme in tears/saliva - Lyses bacteria
Proteases - digest microorganisms
What does the mucus do and where does it come form
sticky secretions in resp/digest passage. Traps microorganisms.
what do defensives do
Antimicrobial peptides secreted by mucus membranes. . Inhibit bacterial & fungal growth.
what do dermcidins do
secretions in sweat that are toxic to bacteria
What are the main 2 phagocytes in cellular defence
1) Macrophages
2) Neutrophils
what are macrophages
derived from monocyte that leaves circulation. It is free & wanders CT or it is fixed an stays in organs
-large phogcytes that engulf cellular debris, foreign particles, cells & present antigen to helper T
what are neutrophils
most abundant in blood and CT.
what is intracellular killing
engulf pathogens by phagocytosis (inside cell)
Lysosomal enzyme digest pathogen
what are toll like receptors
phagocytes have TLR’s that can recognize pathogen associated molecules on the surface of a pathogen.
What is extacellular killing
happens outside the cell
What are the 2 ways neutophils can do extracellular killing
1) Degranulation
2) Neutrophil extracellular trap
what do neutrophils degranulate (3)
1) Proteases - protein digesting enzyme
2) DEfensins - peirce holes in cells
3) Free radicals - Causes respiratory/oxidative burst.
explain neutrophil extracellular trap
Neutrophil dies b/c it releases it’s DNA as a last resort to kill bacteria
what are natural killer cells
- Specific granular lymphocytes that recognize & attack abnormal cells
- Immune surveillance
- Release cytolytic chemicals that destroy virus infected cells/ cancer
- patrol peripheral tissues
- detect lower MHC-1 levels
4 steps of a natural killer cell
1) Recognize abnormal cell
2) Aim (align golgi apparatus)
3) Fire (Perforin makes holes, Granzymes enter cell)
4) Apoptosis (programmed cell death)
What is natural flora
- Bacteria that normal inhabit the epithelial surfaces
- Protect against pathogens
- increase competition & stimulate defence mechanisms.
3 Things that bacteria would have to go through to get beneath the epithelium
1) protective layer or flora
2) Epithelium with tight junction
3) Phagocytes patrol (Macrophages, dendritic) the CT
what is chemical defence
-Chemicals circulating in blood or related by Injured/infected cells & leukocytes
what are pyrogens
chemicals released by phagocytes the have been exposed to pathogens.
-Cause a fever by altering the temperature set point in the hypothalamus. Increased temperature accelerates the repair and enhances the activity of immune cells.
what are interferons
secreted by virus infected cells.
Interfere with viral replication in nearby cells that attract natural killer cells and macrophages
what is complement
- Group of plasma proteins
- Made in liver
- Circulate in blood
- Activated by microbes (activation cascade)
what is the general function of complement
complements the action of other immune defence mechanisms
what are the 3 complement activation pathways
1) Classical pathway
2) Alternative pathway
3) Lectin pathway
what is the classical complement pathway
complement contacts an antigen-antibody complex & becomes activated
what is the alternative complement pathway
complement contacts the surface of a microbe and becomes activated
what is the lectin complement pathway
Complement contacts plasma protein lectin bound to sugar mannose on the surface of a pathogen.
what are the 4 main effects of complement activation
1) Enhances phagocytosis
2) Triggers Inflammation
3) Triggers chemotaxis
4) Causes cell lysis
how does complement enhance phagocytosis
by coating pathogens (making them extra tasty)
how does complement trigger inflammation
by causes MAST cels to release histamine
how does complement trigger chemotaxis
creates a chemical trail that attracts leukocytes
how does complement cause cell lysis
by forming a membrane attack complex. Makes holes in the cell membrane
Explain the formation of the MAC complex
Cascade of activation events that results in a assembly of complement proteins (MAC) that inserts into the bacterial cell wall, forming pores/holes and causes lysis of cell as water flows n
What is inflammation
non-specific response triggered by tissue injury, chemical irritation or pathogens
what are the 4 cardinal signs of inflammation
1) Redness
2) Swelling
3) Heat
4) Pain
What is margination
Leukocytes stick & role along inside of blood vessel wall. Attach to selecting expressed by the blood vessel endothelial cells
what is diapedesis
WBC escape from blood into CT
what is chemotaxis
WBC follow chemical trail to find damage/inflammation
what do inflammatory chemical do
1) attract WBC (chemotaxis)
2) Make endothelium sticky (facilitate margination)
3) increase blood vessel permeability (facilitates diapedesis)
4) Vasodilation
explain inflammatory process and how it contributes to healing
1) Infection/ injury
2) Basophils or mast cells release inflammatory mediators (histamine, kinins, prostaglandins, activated complement proteins)
3) this increases vasodilation, capillary permeability & attracts WBC via chemotaxis
4) The vasodilation causes hyperaemia (increased blood flow) which causes redness & heat which results in increased nutrition, repair & increased WBC. This all contributes to healing.
5) The increased capillary permeability allows fluid leakage & WBC to escape from blood into CT (DIAPEDESIS) this causes swelling & pain. It limits mobility & dilutes harmful substances. Contributes to healing
6) Chemotaxis attracts WBC, which fight pathogens & dispose of damaged cells, leading to healing.
What do inflammatory mediators do
chemicals secreted by cells that trigger inflammation(ex. Histamine, prostaglandins, kinins)
what do dendritic cells do
type of macrophage found in epidermis/mucous membranes. Engul cellular debris, foreign prarticles, cells & present antigen to help T cell
What do performs do
proteins secreted by NK cells & cytotoxic cells that induce apoptosis by degrading cellular proteins & DNA
What do granzymes do
enzymes released by NK cells & cytotoxic cells that induce apoptosis by degrading cellular proteins & DNA
what do antigen presenting cells do
Display non-self antigen on Mhc2 to helper T cells
