10-Innate Host Resistance Flashcards
Susceptibility?
The lack of resistance to a disease.
Immunity?
Ability to ward off a disease.
Immune system?
Recognizes foreign substances or microbes and acts to neutralize or destroy them.
- composed of widely distributed cells, tissues, and organs.
Innate immunity?
Defenses against any pathogen
Adaptive immunity?
Immunity or resistance to a specific pathogen
Components of the first line of defense?
- skin
- mucus membranes and their secretions
- normal microbiota
Components of second line of defense?
- phagocytes, such as neutrophils, eosinophils, dendritic cells, and macrophages
- inflammation
- fever
- antimicrobial substances
Components of third line of defense?
- specialized lymphocytes: T cells and B cells
- antibodies
B cell activation leads to what?
The production of antibodies
What are some direct factors that can impact our physical barriers?
- nutrition
- physiology
- fever
- age
- genetics
What are some indirect factors that can impact our barriers?
- personal hygiene
- socioeconomic status
- living conditions
How does lysozyme act as an antimicrobial secretion?
Hydrolyzes bond connecting sugars in peptidoglycan
How does lactoferrin act as an antimicrobial secretion?
Secreted by activated macrophages and PMNs. Also, sequesters iron from plasma
How does lactoperoxidase act as an antimicrobial secretion?
By producing superoxide radicals
Why is it that the lower respiratory system is free of microbes?
Because of alveolar macrophages in the lungs that eliminate microbes
Paneth cells of the intestinal tract produces these antimicrobial substances? (2)
- lysozyme
- cryptins
Bacteriocins?
Toxic proteins that are lethal to other strains of the same species of closely related bacteria
Three majors activities of the complement system?
- defending against bacterial infections
- bridging innate and adaptive immunity
- disposing of wastes
What are the three pathways of complement activation?
- alternative pathway
- lectin pathway
- classical pathway
This complement path way begins with the activation of C3 and eventually results in the formation of a membrane attack complex?
Alternative complement pathway
This complement pathway is usually dependent on antibody-antigen interactions and result in opsonization, chemotaxis and the membrane attack complex?
Classical complement pathway
This complement pathway begins with the activation of C3 and lectin binding?
Lectin complement pathway
Cytokines?
Soluble proteins or glycoproteins that are released by one cell population that act as intercellular mediators or SIGNALING MOLECULES
These can bind bacterial surfaces and act as opsonins?
Acute phase proteins
What are your granulocytes?
- eosinophils
- basophils
- neutrophils
Name some of the formed elements in the blood. (8)
- RBCs
- Leukocytes
- monocytes
- dendritic cells
- natural killer cells
- t-cells
- b-cells
- platelets
Primary organs and tissues?
Sites where lymphocytes mature and differentiate into antigen-sensitive mature B and T cells
Secondary organs and tissues?
Areas where lymphocytes may encounter and bind antigen
- followed by proliferation and differentiation into fully mature effector cells
These recognize and bind unique PAMPs of viruses, bacteria, or fungi?
Toll-like receptors (TLRs)
Susceptibility?
The lack of resistance to a disease
Inflammation?
Nonspecific response to tissue injury. Characterized by redness, warmth, pain, swelling, and altered function
The presence of antigens in the body ultimately lead to ___________ which leads to the production of antibodies?
B-cell activation
This chemical participates in the first line of defense and is responsible for forming a protective acidic film over the skin surfaces that inhibits microbial growth?
Sebum
What are the three major activities of the complement system?
- defending against bacterial infections
- bridging innate and adaptive immunity
- disposing of wastes
What is opsonization?
Process in which microorganisms or inanimate particles are coated by serum components, thereby preparing them for recognition and ingestion by phagocytic cells.
Name some effects of complement activation.
- opsonization or immune adherence: enhanced phagocytosis
- membrane attack complex: cytolysis
- attract phagocytes
This complement pathway is dependent on integration of host mannose-binding protein (MBP) with pathogen surfaces?
Lectin complement pathway
List three ways that some bacteria can evade the complement system.
- capsules prevent C activation
- surface lipid-carbohydrates prevent membrane attack complex (MAC) formation
- enzymatic digestion of C5a
Autocrines?
Affect the same cell responsible for their production
Paracrines?
Affect nearby cells
Endocrines?
Spread by circulatory system to distant target cells
Monokines?
Released from mononuclear phagocytes
Lymphokines?
Released from T lymphocytes
Interleukins?
Released from one leukocyte and act on another leukocyte
Colony stimulating factors (CsFs)?
Stimulate growth and differentiation of immature leukocyte a in bone marrow
What are the most common causes of fever?
- Viral infection
- bacterial infection
- bacterial endotoxin
These interferons cause cells to produce antiviral proteins that inhibit viral replication?
IFN- alpha and IFN- beta
This interferon causes neutrophils and macrophages to phagocytize bacteria?
IFN- gamma
What are the two ways a microbe can be recognized by a phagocyte?
- opsonin-independent (nonopsonic) recognition
- opsonin- dependent (opsonic) pathway
Pathogen- associated molecular patterns (PAMPs) are unique to microbes, not present in the host. Name two examples.
- Lipopolysaccharide (LPS) of Gram-negative bacteria
- Peptidoglycan of gram-positive bacteria
These recognize pathogen associated molecular patterns (PAMPs)?
Pattern recognition receptors (PRRs) on/ in phagocytic cells
These are a class of PRRs that function exclusively as signaling receptors?
Toll-like receptors (TLRs)
Phagolysosome?
Vacuole which results from the fusion of phagosome with lysosome
How do streptococcus pyogenes and S. pneumoniae evade phagocytosis?
Inhibit adherence: M proteins, capsules
How does staphylococcus aureus evade phagocytosis?
Kills phagocytes: Leukocidins
How does Listeria monocytogenes evade phagocytosis?
Lyase phagocytes: membrane attack complex
How do Shigella and Rickettsia evade phagocytosis?
Escape the phagosome
How do HIV and Mycobacterium tuberculosis evade phagocytosis?
Prevent phagosome-lysosome fusion
How does Coxiella burnettii evade phagocytosis?
Survive in phagolysosome
Why is antigen presentation important?
It is important because it allows wandering lymphocytes to become activated. Also, because it links nonspecific and specific immune responses
What are some of the chemical mediators involved in the a cute inflammatory response?
- selectins
- integrins
- chemotaxins
List the processes involved in the acute inflammatory response?
Neutrophil rolling—> marginal ion—> diapedesis—> extravasion
What is the most common cause of fever?
Viral or bacterial infection or bacterial endotoxin
What are some advantages of fever as a defense mechanism (3)?
- T-cell production increases dues to increase in IL-1
- increase transferrins
- speeds up repair process
What are some disadvantages to fever as a defensive mechanism?
- tachycardia
- acidosis due to increased metabolic rate
- dehydration
- death above 44C to 46C (112F to 1114F)
What is the function of histamine released by a damaged cell?
Vasodilation, increases permeability of blood vessels
What are the functions of kinins released by damaged cells?
Vasodilation, increase permeability of blood vessels
What are the effects of prostaglandins released by damaged cells?
Intensify histamine and kinin effects
What are the effects of leukotrienes released by damaged cells?
Increased permeability of blood vessels, phagocytic attachment
