week 6 - immunity Flashcards
mostly definitions
define virus
a microscopic, infectious agent that requires a host cell in order to replicate. it consists of a nucleic acid (DNA or RNA) enclosed in a protein coat (capsid), sometimes with a lipid envelope. viruses infect living organisms, hijacking cellular machinery to reproduce, often causing diseases.
define host range
refers to the variety of host species or cell types that a virus, parasite, or pathogen can infect. it is determined by factors such as receptor compatibility, immune system defences, and the pathogen’s ability to replicate within the host. host ranges could be narrow (infecting only one species) or broad (infecting multiple species).
for HIV, define primary infection
the initial stage of HIV infection, occurring within a few weeks of exposure, marked by rapid viral replication and flu-like symptoms as the immune system responds.
for HIV, define clinical latency
a prolonged phase where the virus remains active but replicates at lower levels; the individual may have no symptoms while the immune system gradually weakens.
for HIV, define opportunistic diseases
infections and conditions that occur as HIV weakens the immune system, such as pneumonia, tuberculosis, and certain cancers, often signalling progression to AIDS.
list the 5 primary targets of antibiotics
1) cell wall synthesis
2) protein synthesis
3) nucleic acid synthesis
4) metabolic pathways
5) cell membrane integrity
define antibiotic
a substance that kills or inhibits the growth of bacteria, typically used to treat bacterial infections.
define intrinsic immunity
intrinsic immunity consists of physical and chemical barriers such as the skin and mucous membranes, that prevent microorganisms from entering the body. these defences act as the first line of protection by blocking pathogens before infection can begin.
define innate immunity
innate immunity is the body’s immediate, non-specific defence against pathogens, involving cells like macrophages and neutrophils, as well as chemical defences like inflammation. it provides rapid protection without requiring prior exposure to a pathogen.
define adaptive/acquired immunity
adaptive/acquired immunity is a specific defence mechanism that develops after exposure to a pathogen, involving immune cells like B and T lymphocytes. it provides long-term protection through immune memory, allowing a faster and stronger response upon future encounters with the same pathogen.
define opportunistic pathogen
a microorganism that usually does not cause disease in a healthy individual but can lead to infection when the host’s immune system is compromised or when there is a disruption in normal flora.
define portal of entry
the route through which a pathogen enters the body to initiate an infection. common portals of entry include the respiratory tract, GI tract, urogenital tract, skin, and mucous membranes.
define portal of exit
the route through which a pathogen leaves the body to spread to other hosts. common portals of exit include the respiratory tract (coughing or sneezing), GI tract (feces or vomit), urogenital tract (urine or genital secretions), skin (wounds or lesions), and bodily fluids like blood and saliva.
define virulence
the degree or relative measure of pathogenicity, referring to how effectively a pathogen can cause disease once it enters the host. it is not about severity but the overall capacity of a pathogen to infect the host.
*how good it is at causing disease
define pathogenicity
indicates whether a pathogen can cause disease.
*can it cause disease? (yes or no)
define anti-phagocytic virulence factors
molecules or mechanisms used by pathogens to evade phagocytosis. these factors enhance the pathogen’s ability to survive and cause infection.
ex:
-capsules; inhibit phagocyte attachment by surrounding the bacterium.
-incomplete phagocytosis; capsule around bacterium within the phagocyte prevents the phagosome from fusing with the lysosome.
define reticular connective tissue
a loose connective tissue made of reticular fibers and reticulocytes. it forms a supportive mesh in organs like lymph nodes, the spleen, and bone marrow, aiding in structural support and immune function.
define lymphatic capillaries
thin-walled, blind-ended vessels with overlapping endothelial cells that act as one-way valves, allowing ISF, proteins, and debris to enter. they function to drain excess ISF and transport it as lymph back to the bloodstream, helping maintain fluid balance and support immune function.
define collecting vessels
larger lymphatic vessels that receive lymph from lymphatic capillaries and transport it toward lymph nodes. they have valves to prevent backflow and ensure the one-way movement of lymph toward the bloodstream.
define lymph trunks
larger lymphatic vessels that collect lymph from multiple collecting vessels and drain it into the lymphatic ducts. they are named based on the regions they serve, such as the lumbar trunk, jugular trunk, etc,.
define lymph ducts
the largest lymph vessels, receiving lymph from lymphatic trunks and returning it to the bloodstream. the two main ducts are the thoracic duct (which drains most of the body), and the right lymphatic duct (which drains the right upper quadrant).
what are the two functions of the viral genome in the host cell?
1) replication: the viral genome serves as a template to produce new copies of itself, ensuring that each new virion contains a complete set of genetic instructions.
2) gene expression: the viral genome directs the synthesis of viral proteins needed for replication and assembly. it provides instructions for making structural proteins such as capsid proteins, and functional proteins such as enzymes needed for replication.
in regard to antibiotics, define spectrum of action
refers to the range of bacteria that an antibiotic can target. it is classified as:
-broad spectrum; effective against a wide variety of bacteria (including gram-positive and gram-negative species).
-narrow spectrum; targets specific bacterial groups, minimizing disruption to normal microbiota.
