Nonspecific Host Defenses Flashcards
Chapter 16
What is Resistance?
Ability to prevent disease (aka immunity)
What is Susceptibility?
Vulnerability to disease
What is Innate Resistance (Non-Specific)?
Defense mechanism against ANY pathogen
What is Adaptive Resistance (Specific)?
Define mechanism against SPECIFIC pathogen
Examples of Innate Resistance (5):
- skin
- mucosa
- phagocytosis
- inflammation
- fever
Examples of Adaptive Resistance (2):
- cell mediated immunity (CMI)
- humoral immunity
What cell is involved in cell mediated immunity?
T cells
What cells is involved in humoral immunity?
B cells and antibodies (Ab)
What are the first line of defense? (2)
- intact skin
- mucous membranes
What are the second line of defense? (4)
- phagocytes
- inflammation
- fever
- antimicrobial substances
What are the third line of defense?
- humoral immunity (bursa maturation)
- cell mediated immunity (thymus maturation)
(T/F) The different components of the immune system are mutually exclusive
False, they interact with each other
Describe Innate Immunity (3)
- present at birth
- always present with rapid responses
- no specific recognition/memory
What activates Innate Immunity?
Toll Like Receptors (TLR) proteins on membranes of defensive cells
What do TLR’s attach to?
Pathogen Associated Molecular Patterns (PAMP’s): LPS, peptidoglycan, capsule proteins
(T/F) Cells release chemicals that regulate the immune response
True
What type of barriers do Innate Defenses provide? (2)
- physical
- mechanical
What are examples of physical barriers? (2)
- intact skin
- mucous membranes
What are examples of mechanical barriers? (6)
- tears
- saliva
- mucus
- cilia
- mucus-coated hairs of nose
- flow of urine
What are examples of Chemical Factors in Nonspecific Defenses? (7)
- sebum
- perspiration
- lysozyme
- gastric juice
- vaginal secretions
- stomach acid
- transferrin
Describe sebum and its affects (4):
- contains unsaturated fats
- inhibits growth of some bacteria
- keeps pH of skin low
- protective coat over skin
What does Perspiration do?
Eliminates wastes and flushes microbes
What does Lysozyme do?
Degrades peptidoglycan layer of Gram (+) bacteria
What are examples of Lysozyme? (5)
- tears
- saliva
- perspiration
- tissue fluids
- nasal secretions
Describe Gastric Juice (2)
- contains HCl (hydrochloric acid)
- pH: 1.2 - 3
What does stomach acid do?
Kills most bacteria because of its low pH (some toxins + microbes survive)
What does Transferrin do?
Prevents bacteria from using iron in the body
How does Normal Flora aid in innate protection? (4)
- prevents overgrowth of pathogens (competition)
- produces substances that kill pathogens (bacteriocins)
- change pH and oxygen
- probiotics
Define Bacteriocins
Substances that kill pathogens
What does the Second Line of Defense do?
Control pathogens/infections when the first line has failed
Describe the Second Line of Defense
(4):
- defensive cells (phagocytes)
- inflammation
- fever
- antimicrobial substances (interferon + complement)
What are examples of Antimicrobial Substances? (2)
- interferon
- complement
What are the 3 granulocytes?
- neutrophils
- basophils
- eosinophils
Describe Neutrophils (3)
- 60-70% of WBCs
- Polymorphonuclear neutrophils (PMNs)
- Can enter tissues (highly phagocytic)
Describe Basophils (3)
- 0.5-1.0% of WBCs
- inflammation & allergies, release histamines
- tissue mast cells are similar
Describe Eosinophils (3)
- 2-4% of WBCs
- allergies and helminth infections
- may be phagocytic
What are the 2 Monocytes/Macrophages?
- Monocyte
- Dendritic Cells
Describe Monocytes (4)
- 3-8% of WBCs
- macrophage = mature
monocytes/professional phagocytes - process antigens (Ag)
- secrete compounds that regulate immune system
What elicits an antibody response?
Antigens
Describe Dendritic Cells (3)
- derived from monocytes
- skin, mucous membranes, lymph nodes
- destroy by phagocytosis, initiate adaptive response
Which cell makes up around 60 - 70% of WBCs?
Neutrophils
Which cell makes up around 0.5 - 1.0% of WBCs?
Basophils
Which cell makes up around 2 - 4% of WBCs?
Eosinophils
Which cell makes up around 3 - 8% of WBCs?
Monocytes/Macrophages
Which cell makes up around 20 - 25% of WBCs?
Lymphocytes
What are the 3 types of Lymphocytes?
- Natural Killer Cells
- B Lymphocytes
- T Lymphocytes
What do Natural Killer Cells do? (2)
- kill infected/tumor cells
- recognize abnormal proteins on surface
What do B Lymphocytes do?
Produce Antibodies
What do T Lymphocytes do?
Involved in cell mediated immunity
What lymphatic tissues do Lymphocytes circulate? (7)
- tonsils
- lymph nodes
- spleen
- thymus gland
- bone marrow
- appendix
- peyer’s patches (small intestine)
What is Phagocytosis?
Cell ingesting any particulate matter (microbes)
What are Phagocytes?
Cells that ingest microbes
What type and line of defense are Phagocytes?
- Nonspecific mechanism
- Second Line of Defense
What is a Leukocyte?
White Blood Cell (WBC)
What are the 5 basic types of WBCs?
- granulocytes (3)
- monocytes
- lymphocytes
What is Leukopenia?
Decrease in WBCs
What is Leukocytosis?
Increase in WBCs
What is a possible cause of Leukopenia? (1)
AIDS
What is a possible cause of Leukocytosis? (2)
- Infectious mononucleosis
- Gonorrhea
What do Neutrophils, Monocytes, and Dendritic cells do when there’s an infection?
Leave circulation -> Enter tissues -> Migrate to infection site
Which WBC arrives to the site of infection/injury early in the course of an infection?
Neutrophils (PMNs)
What do monocytes do at the site of infection? (2)
- enlarge and mature into macrophages
- become phagocytic
Which WBC reaches the area later in the infection process?
Monocytes/Macrophages
What is Chemotaxis?
Movement of phagocytes to site of infection due to attraction of released chemicals
What releases Chemotaxins? (4)
- basophils
- tissue
- bacteria
- complement
What is Adherence?
Phagocyte ATTACHMENT to bacterium
How can capsules affect attachment?
Resists attachment
What protein prevents attachment?
M protein
What facilitates adherence?
Attachment of PAMPs (pathogen associated molecular pattern) to TLRs (toll like receptors)
What are Opsonins?
Proteins that promote phagocytosis
What is Opsonization?
Promotions of phagocytosis (by Ab + components of the complement system)
What is Ingestion?
Engulfment of the bacterium
What is the phagocyte plasma membrane that extends in phagocytosis called?
Pseudopods
Where is the engulfed bacterium held?
Phagosome
What is a Phagosome
Membrane bound vesicle
What is Digestion?
Fusion of phagosome with a lysosome
What is a Phagolysosome?
Fusion of phagosome with a lysosome
What are the two ways bacteria can be killed during digestion?
- anaerobically (hydrolytic or lysosomal enzymes)
- aerobically (toxic oxygen compounds)
When bacterium is killed aerobically due to toxic oxygen compounds it is called:
Respiratory Burst
What 2 structures inhibit adherence?
- capsules
- protein M
What 3 microbes are not killed when ingested?
- Staphylococci
- Trypanosoma
- Mycobacterium, HIV, Plasmodium
How do Staphylococci avoid being killed during ingestion?
Secreting leukocidin
How do Trypanosoma avoid being killed during ingestion?
Lyse phagocyte membranes
How do Mycobacterium, HIV, Plasmodium avoid being killed during ingestion?
Prevent fusion of phagosome and lysosome
How do Biofilms evade phagocytosis?
Phagocytes can’t detach them from the surface
What are the tell-tale signs of inflammation? (4)
- redness
- heat
- pain
- swelling
What typically causes inflammation?
Cells and acute phase proteins (complement, fibrinogen, kinins)
(T/F) Microbes can initiate inflammation
True
(T/F) Inflammation cannot result in loss of function
False
What are the functions of inflammation? (3)
- destroys/removes microbes
- limit spread of microbes
- repairs tissues
What can enhance inflammation?
Microbial structures (LPS, flagella, DNA) attaching to TLRs = induces acute phase proteins
What does the Vasodilation of Blood Vessels mean?
Increased diameter of blood vessels
What does Vasodilation of Blood Vessels cause? (2)
- increased blood flow
- redness and heat (at site)
What do Mediators do?
Increase permeability in capillaries
What is Edema?
Blood cells + fluid entering tissues (swelling)
What can cause inflammation?
Chemical mediators released from damaged cells
What are 4 examples of chemical mediators?
- histamine
- kinins
- prostaglandins
- leukotrienes
What is Margination?
Phagocytes (Monocytes and PMNs) migrate to site & stick to blood vessel walls
What is Diapedesis?
Phagocytes move between the endothelial cells of the blood vessel walls
What mediates migration of phagocytes into tissues?
Chemotaxins
What enters the tissue’s first?
PMNs (like neutrophils)
What is pus made of?
Dead cells and fluid
What is a pyogenic infection?
Any infection that forms pus
Blood fluid in tissue is called:
Edema/swelling
What is the final stage of inflammation?
Tissue Repair
Is inflammation benifical?
Yes, but chronic inflammation can cause permanent changes in tissues
What is a fever?
Systemic response to infection
What part of the brain causes fevers?
Hypothalamus
What causes a fever?
- bacterial endotoxin (exogenous pyrogen)
- IL-1 (endogenous pyrogen)
What do shivers and chills do to body temperature?
Raise body temperature
What does sweating or crisis do to body temperature?
Lowers body temperature
What happens during a fever? (4)
- T lymphocytes activated
- Intensifies Interferons (stops replication of some viruses)
- Decreases iron uptake (some)
- May increase tissue repair
What do interferons effect? (1)
Viruses
What do Complements effect? (2)
- Bacteria
- Viruses
What are examples of Antimicrobial Substances? (4)
- interferons
- complement
- iron binding proteins
- antimicrobial peptides
What are Interferons?
Small proteins that interfere with the replication of viruses
Who discovered Interferons and when?
Lindenmann & Isaacs, 1957
How do interferons act?
Stimulating cells to make AntiViral Proteins (AVPs) -> stops viral replication
What are the 3 types of Interferons?
- Alpha-interferon
- Beta-interferon
- Gamma-interferon
Which cells produce which interferon?
Every cell can make all 3, but specific cell types produce specific interferons
What is considered to be the First Line of Defense for Viral Infections?
Interferons
Are interferons specific?
They are HOST specific (not viral)
What cells produce alpha-interferons?
B Lymphocytes and Monocytes
What cells produce beta-interferons?
Fibroblasts and Epithelial Cells
What cells produce gamma-interferons?
T-Cells
How many proteins make up the Complement System?
30
Where are the proteins in the Complement System found?
In fluid portion of the blood (serum)
How are individual proteins of the Complement System activated?
By the presence of foreign cells (bacteria, virus)
What is the Nonspecific mechanism for removing foreign cells?
The Complement System
Define Cascade in reference to the Complement System?
First activated protein causes a domino affect where the protein next to it is activated (and so on)
What are the three pathways of the Complement System?
- classical pathway
- alternative pathway
- lectin pathway
Complements destroy microbes by (3):
- cytolysis
- inflammation
- phagocytosis