Test 4 Flashcards
normal (resident) flora
Microbes that engage in mutual or commensal associations
Infection
a condition in which pathogenic microbes penetrate host defenses, enter tissues, and multiply
Pathogen
infectious agent
Infectious disease
an infection that causes damage or disruption to tissues and organs
Transients
microbes that occupy the body for only short periods
Residents
microbes that become established
microbial antagonism
Bacterial flora benefit host by preventing overgrowth of harmful microbes
Endogenous infections
occur when normal flora is introduced to a site that was previously sterile
Transients
influenced by hygiene
Residents
stable, predictable, less influenced by hygiene
Probiotics
introducing known microbes back into the body
Prebiotics
nutrients that support growth of “good” flora
True pathogens
Capable of causing disease in healthy persons with normal immune defenses
ex: Influenza virus, plague bacillus, malarial protozoan
Opportunistic pathogens
Cause disease when the host’s defenses are compromised or when they grow in part of the body that is not natural to them
ex: Pseudomonas sp & Candida albicans
virulence factor
Characteristic or structure that contributes to the ability of a microbe to cause disease
Portals of entry
Characteristic route a microbe follows to enter the tissues of the body
Exogenous agents
Originate from source outside the body
Endogenous agents
Already exist on or in the body (normal flora)
STORCH
○ Syphilis
○ Toxoplasmosis
○ Other diseases
-Hepatitis B
-HIV
-Chlamydia
○ Rubella
○ Cytomegalovirus
Herpes simplex virus
Ex’s of adhesion
-Fimbriae
-Flagella
-Glycocalyx
-Cilia
-Sucker
-Hooks
-Barbs
Antiphagocytic factors
Used to avoid phagocytosis
leukocidins
Toxic to white blood cells that are produced by species of staphylococcus and streptococcus
Slime layer or capsule makes…
phagocytosis difficult
Virulence factors
Traits used to invade and establish themselves in the host, also determine the degree of tissue damage that occurs – severity of disease
Exoenzymes
Dissolve extracellular barriers and penetrate through or between cells
Toxigenicity
Capacity to produce toxins at the site of multiplication
Endotoxin
-Toxin that is not secreted but is released after cell is damaged
-Composed of lipopolysaccharide (LPS), part of the outer membrane of gram-negative cell walls
Exotoxin
-Toxin molecule secreted by a living bacterial cell into the infected tissue
-Strong specificity for a target cell
- Hemolysins
Localized infection
Microbes enter the body and remains confined to a specific tissue
Systemic infection
Infection spreads to several sites and tissue fluids usually in the bloodstream
Focal infection
Infectious agent breaks loose from a local infection and is carried to other tissues
Mixed infection
-Several microbes grow simultaneously at the infection site
-Polymicrobial
Primary infection
initial infection
Secondary infection
Another infection by a different microbe
Acute infection
Comes on rapidly, with severe but short-lived effects
Chronic infections
Progress and persist over a long period of time
Carrier
-Individual who inconspicuously shelters pathogen and spreads it to others
-May or may not have experienced disease due to the microbe
Asymptomatic carrier
Shows no symptoms
Passive carrier
Contaminated healthcare provider picks up pathogens and transfers them to other patients
Incubation carriers
Spread the infectious agent during the incubation period
Convalescent carriers
Recuperating without symptoms
Chronic carrier
Individual who shelters the infectious agent for a long period
Vector
Live animal (other than human) that transmits an infectious agent from one host to another
zoonosis
An infection indigenous to animals but naturally transmissible to humans
Communicable disease
-Infected host can transmit the infectious agent to another host and establish infection in that host
-Highly communicable disease is contagious
Non-communicable infectious
- does not arise through transmission from host to host
- Occurs primarily when a compromised person is invaded by his or her own normal microflora
- Contact with organism in natural, non-living reservoir
Direct contact
Physical contact or fine aerosol droplets
Indirect contact
Passes from infected host to intermediate conveyor and then to another host
Innate defenses
Provide nonspecific resistance to infection - natural and present at birth
Adaptive immunities
Specific / Must be acquired by exposure
Lysozyme
an enzyme that hydrolyzes the cell wall of bacteria, in tears (nonspecific)
White blood cells
(leukocytes) – innate capacity to recognize and differentiate any foreign material
Pathogen-associated molecular patterns (PAMPs)
molecules shared by microorganisms
Pathogen recognition receptors (PRRs)
receptors on WBCs for PAMPs
mononuclear phagocyte system
macrophages ready to attack and ingest microbes that passed the first line of defense
Formed elements
RBCs, WBCs, platelets
Serum
-Liquid portion of the blood after a clot has formed
-Depleted of clotting factors
Plasma
- 92% water
- Metabolic proteins, globulins, clotting factors, hormones, and all other chemicals and gases to support normal physiological functions
Stem cells
undifferentiated cells, precursor of new blood cells
Leukocytes
White blood cells
Granulocytes
lobed nucleus
Agranulocytes
unlobed, rounded nucleus
Neutrophils
(Gran) 55-90%
-Lobed nuclei with lavender granules
- Phagocytes
Eosinophils
1-3% (Gran)
○ Orange granules and bilobed nucleus
○ Destroy eukaryotic pathogens
Basophils
0.5% (gran)
○Constricted nuclei, dark blue granules
○ Release potent chemical mediators
Mast cells
Nonmotile elements bound to connective tissue
Lymphocytes
20-35%
○ Specific immune response
- B and T cells
B (humoral immunity)
Activated B cells produce antibodies
T cells (cell-mediated immunity)
Activated T cells modulate immune functions and kill foreign cells
Monocytes, macrophages
3-7%
-Largest of WBCs, kidney-shaped nucleus
-Phagocytic
-Macrophages:
final differentiation of monocytes
Dendritic cells
Antigen-presenting cells
Primary lymphoid organs
-Sites of lymphocytic origin and maturation
-Thymus and bone marrow
Secondary lymphoid organs and tissues
- Circulatory-based locations such as spleen and lymph nodes
- Collections of cells distributed throughout body tissues
○ Skin: SALT
○ Mucous membranes: MALT
○ Gut: GALT
Thymus
- High rate of growth and activity until puberty, then begins to shrink
○ Site of T-cell maturation
Lymph nodes
Small, encapsulated, bean-shaped organs stationed along lymphatic channels and large blood vessels of the thoracic and abdominal cavities
Spleen
-Structurally similar to lymph node
-Filters circulating blood to remove worn out RBCs and pathogens
Miscellaneous lymphoid organs
-GALT
-peyers patches
2nd defense line actions
- Recognition
- Inflammation
- Phagocytosis
- Interferon
- Complement
Inflammatory response
- redness
- warmth
- swelling
- pain
Diapedesis
Migration of cells out of blood vessels into the tissues
Chemotaxis
Migration in response to specific chemicals at the site of injury or infection
Exogenous pyrogens
products of infectious agents
Endogenous pyrogens
liberated by monocytes, neutrophils, and macrophages during phagocytosis; interleukin-1 (IL-1) and tumor necrosis factor (TNF)
Fever
Initiated by circulating pyrogens which reset the hypothalamus to increase body temperature
Benefits:
- Inhibits multiplication of temperature-sensitive microorganisms
- Impedes nutrition of bacteria by reducing the available iron
- Increases metabolism and stimulates immune reactions and protective physiological processes
Toll-like receptors =
Pathogen Recognition Receptors (PRRs)
recognition of foreign cells
Active immunity
-Creates memory, takes time to develop
- Provides long-term protection
Passive immunity
- Does not create memory, acts immediately
- Provides short-term protection
Natural immunity
Acquired as part of normal life experiences
Artificial immunity
Acquired through a medical procedure such as a vaccine