Ch 16: Innate Immunity Flashcards
What is the difference between “resistance” and “immunity”
- Resistance: unable to allow for productive infection
- Immunity: active process to prevent progression of infection
What is the first line of defense of the immune system? (3)
- Physical barrier (intact skin)
- Chemical factors (mucous membrane secretions)
- Normal microbiota
What is the second line of defense of the immune system? (4)
Nonspecific physiologic processes:
- Inflammation
- Fever
- Antimicrobial substance production
- Phagocyte infiltration (neutrophils, eosinophils, dendritic cells, and macrophages)
The ciliary escalator of the respiratory tract moves the mucus blanket at a rate of ______.
1-3 cm/hr
What properties of the epidermis make it a good physical barrier for the immune system? (3)
- Dryness inhibits microbes
- Water-tightness blocks microbes
- Shedding removes microbes
What glands produce sebum?
Sebaceous glands
What is sebum?
- Complex mixture of fatty acids and triglycerides that have anti-microbial activity
- Acidic
A pH of ____ inhibits bacteria and fungi
6 or lower
True or false. Urea can be bacteriostatic or bacteriocidal
True
What is lysozyme?
Small enzyme that attacks the peptidoglycan chains in the cell walls of bacteria, causing the cells to burst.
Who discovered lysozyme as an antibiotic?
Alexander Flemming (also discovered penicillin)
Does sebum contain acid, lysozyme, or antibacterial substances?
Acid and antibacterial substances
Does sweat contain acid, lysozyme, or antibacterial substances?
Lysozyme and antibacterial substances
Do tears contain acid, lysozyme, or antibacterial substances?
Lysozyme
Does saliva contain acid, lysozyme, or antibacterial substances?
ALL
Does gastric juice contain acid, lysozyme, or antibacterial substances?
Acid
Does urine contain acid, lysozyme, or antibacterial substances?
Acid and antibacterial substances
Do vaginal secretions contain acid, lysozyme, or antibacterial substances?
Acid
____ discovered the causative agent of peptic ulcers was H. pylori by drinking a solution of the bacterium and treating himself with antibiotics
Barry Marshall
What cell type gives rise to all other blood cell types?
Multipotent hematopoietic stem cells
Which white blood cells produce histamine?
Basophils
Which white blood cells are responsible for killing parasites?
Eosinophils
Which white blood cells are responsible for phagocytosis but are not antigen-presenting cells?
Neutrophils
Which white blood cells are responsible for phagocytosis and can act as antigen-present cells?
Monocytes (macrophages) and dendritic cells
Which white blood cells are responsible for cell-mediated immunity?
T-cells
Which white blood cells produce antibodies?
B-cells
Which white blood cells destroy target cells (infected or cancerous)
Natural killer cells
What is leukocytosis?
Increased WBCs
What is leukopenia?
Decreased WBCs
Where do the lymphatic ducts ultimately drain?
Left and right subclavian veins, ultimately back to the heart
Which type of phagocytic WBC isshort-lived and only predominate early infections?
Neutrophils
Which type of phagocytic WBC is can last for several months and predominate later infections?
Macrophages
Explain the phases of phagocytosis (7)
- Chemotaxis and adherence of pseudopods
- Ingestion of target
- Formation of phagocytic vesicle or phagosome
- Fuse with lysosome to form a phagolysosome
- Enzymatic digestion of target
- Formation of residual body
- Discharge of indigestible material
What are toll-like receptors (TLRs)?
- Proteins on cell surfaces throughout the body
- Provide adherence for macrophage pseudopods
- Recognized pattern-recognition receptors
How are Streptococcus pyogenes and S. pneumoniae able to evade phagocytosis?
Their M proteins and capsules inhibit adherence
How is Staphylococcus aureus able to evade phagocytosis?
Produces leukocidins that kill phagocytes
How is Listeria monocytogenes able to evade phagocytosis?
Has a membrane attack complex that is able to lyse phagocytes
How are Shigella and Rickettsia able to evade phagocytosis?
They can escape the phagosome
How are HIV and Mycobacterium tuberculosis able to avoid phagocytosis?
Prevent phagosome-lysosome fusion
How is Coxiella burnettii able to evade phagocytosis?
Can survive inside the phagolysosome
What is the purpose of inflammation? (3)
- Destroy and remove injurious agents
- Limit the agent’s effects by walling it off
- Speed up damage repair
What is margination?
Near the site of infection, phagocytes gather and stick to endothelium (blood vessels)
What is diapedesis?
At the site of infection, phagocytes squeeze between endothelial cells
Describe the process of inflammation (8)
- Damaged cells release signaling molecules
- Blood clot and abcess form
- Vasodilation
- Phagocytes migrate
- Margination
- Diapedesis
- Phagocytosis
- Tissue repair (epidermis and dermis regenerate)
What are the signaling molecules released by damaged cells during inflammation and what are their functions? (4)
- Histamine - vasidilation, increased permability of blood vessels
- Kinins - vasodilation, increased permability of blood vessels
- Prostaglandins - intensify histamine and kinin effects; induce fever
- Leukotrienes - increased permeability of blood vessels, phagocytic attachment
Increased permeability of blood vessels results in ____ or _____
Edema or swelling
Gram(-) endotoxin causes phagocytes to release ____
IL-1
What are the advantages and disadvantages of a fever?
Adv:
- Increases transferrins
- Increases IL-1 activity
- Produces interferon
Dis:
- Tachycardia
- Acidosis
- Dehydration
- 44-46℃ (111 ℉) is fatal
What is the complement system?
- An enzyme cascade that:
- Damages bacterial plasma membranes
- Increases ability of antibodies and phagocytic cells to clear microbes and debris
- Promotes inflammation
In complement cascade activation, C1 is activated by ______.
Microbe-antibody complexes
In complement cascade activation, C1 splits _____, which then split _____.
- C1 → C2 and C4
- C2 → C2a and C2b
- C4 → C4a and C4b
In complement cascade activation, ____ and ____ combine together and they split ____.
C2a and C4b → C3
In complement cascade activation C3 splits into _____ and _____ to initiate the complement cascade.
C3 → C3a and C3b
What is the function of C3b in the complement cascade? (2)
- Bind to microbes and enhance phagocytosis (opsonization)
- Splits C5
What is the membrane attack complex?
- C5b, C6, C7, C8, and multiple C9 fragments
- Punches holes in microbes causing lysis
In the complement cascade _____ and ____ bind to mast cells which release histamine and other signaling molecules
C3a and C5a
In the complement cascade ____ is a chemotactic factor, which attracts phagocytes to the site of infection
C5a
What are siderophores?
Secreted bacterial proteinst that sequester iron from their environment and allow for microbes to more easily take it up
What are transferrins?
Iron binding protein in animals that trasport and store iron
How large are antimicrobial peptides?
12-15 amino acids long
What are interferons (IFNs)?
Cytokines that cause cells to produce antiviral proteins that inhibit viral replication (alpha and beta) or cause neutrophils and macrophages to phagocytize bacteria (gamma)
