14.0 Flashcards
What is an infection?
Pathogenic microorganisms penetrate hosts and multiply
What is another name for a virus?
Obligate intracellular parasites: rely on infecting host and using its machinery to replicate and live.
A fully assembled infectious virus is called
virion
What is the structure of a virus?
protein shell[capsid] surrounding nucleic acid core[DNA/RNA]
Difference between HIV, Papilloma virus
poxvirus
-HIV: enveloped, outer phospholipid/glycoprotein coat
-Papilloma virus: Naked: (no envelope)
-Poxvirus: Complex, have extra structures
Fill it in:
Virus: Possess only the ___needed to ___a host cell and
___ its activity
genes, invade, redirect
HIV
-enveloped retrovirus [ single-stranded RNA genome that uses a reverse transcriptase to store its genetic info as DNA that is then integrated into the host using an integrase enzyme]
-Once integrated, the viral DNA is referred to as a provirus.
Shingles is the result of what?
dsDNA virus, after recovery from chickenpox it can lie dormant in the nervous system, later its activated and travels along nerve pathways to the skin
Damage as result of viral infection is …
What are some examples?
Cytopathic Effects[CPE]
Syncytium: mass multinucleated cell
Inclusion: body suspended in cytoplasm
Bacteria
produce toxins that disrupt cell function
Ex: Cholera toxin: bacteria caused the small intestine to release large amounts of water into the large intestine causing diarrhea and dehydration
What is penicillins?
it is an antibiotic that inhibits formation of bacterial cell wall
What is tetracyclines?
it is an antibiotic, inhibit protein synthesis of bacteria
What is quinolines?
it is an antibiotic, that blocks DNA grac which is responsible for the unwinding of DNA, unable to do so means bacteria can’t replicate
How does our body fight off infections?
-skin resist pathogen insertion
-an acidic environment like the stomach kills bacteria
-specificity of viruses to host cell receptors
-lysozyme: damages bacterial cell walls[saliva]
-mucous membrane: chemical viral inhibitors, prevent attachment
-innate immune system, like phagocytosis
-adaptive/acquired immune system
What is the innate immune system?
nonspecific, acts sooner than specific responses, occurs in response to general components of pathogens or to factors released by damaged cells.
What are DAMPs?
cells are damaged or die, they release DAMPs which can bind to
What 3 systems can activate the innate immune system?
- PAMPs, pathogen-associated molecular compounds
2.DAMPs, damage-associated molecular compounds
3.PRRs pattern recognition receptors
What are PRR?
Are receptors found on certain immune cells, such as phagocytic cells. They are responsible for identifying and binding to PAMPs and DAMPs
Ex: TLR(Toll Like Receptors) usually expressed on sentinels
What are sentinel cells?
Sentinel cells are immune cells that act as the first line of defense against pathogens.
What are PAMPs?
Found on pathogens, that are recognizable by pattern recognition receptors (PRR) on immune cells, binds it activates innate immune system
Ex: lipopolysaccharide (LPS) found on outer bacterial membrane
What are the 4 innate immune responses?
Inflammation
Phagocytosis
Interferon
Complement
What is inflammation
innate immune response
interferes with further pathogen
replication/multiplication
Chemokine
When there is tissue damage or infection, cells at the site release chemokines, which act as chemical signals. These chemokines attract immune cells, such as neutrophils and monocytes, to the site through a process called chemotaxis. The
chemotaxis
tendency of cells to migrate in response to a chemical stimulus
-Monocytes are attracted to a damaged site
function of histamine
Histamine increases the permeability of the
capillaries to white blood cells and some proteins, to allow them to engage pathogens in the infected tissues.
What are the stages of inflammation?
- bacteria enters through skin
2.histamine release
3.histamines+ cytokines filate local blood vessels - chemokines attract neutrophils, which pass b/w cells of blood vessel wall
- neutrophils engulf the pathogens and destroy them
During inflammation, chemical mediators help cause fever, stimulate white blood cells (wbc=leukocyte),
which prevent the spread of the pathogen. What are some examples?
TNF (chemotaxis, phagocytosis), IFN (inhibits virus replication), IL (activate wbc)
IFN
Stands for Interferon
Binding of a virus to a host cell initiates IFN synthesis, IFN is secreted by the cell into the extracellular space, Binds to another host cell, Induces production of proteins, Degrade viral RNA or prevent translation of viral proteins
-Not virus-specific
Phagocyte
A class of white blood cells capable of engulfing other cells
and particles
types:
-Neutrophils-a type of granulocyte, short lived
-Monocytes
-Macrophages
phagocytosis
Type of endocytosis: cell membrane actively engulfs large
particles or cells into vesicles
What is cytokine?
Signaling molecules produced by the immune system, play a crucial role in cell communication during immune responses.
Examples of cytokines include interferons, interleukins, and tumor necrosis factors.
What is pyrogen?
Pyrogen is a polypeptide that can induce fever by causing metabolic changes in the hypothalamus, which is the part of the brain that regulates body temperature. Pyrogens can be exogenous, meaning they are produced by infectious agents, or endogenous, meaning they are produced by cells in the body such as macrophages.
What are macrophages?
Macrophages are a type of white blood cell that is capable of engulfing and digesting other cells and particles. They are part of the innate immune system.
Fever can ..
inhibits multiplication of temperature sensitive viruses
Stem cells in the bone marrow can become…
- Granulocytes- class of wbc, have granules in their cytoplasm, neutrophils, eosinophils, and basophils.
- Monocytes- class of wbc, go to infection site and differentiate into macrophages and dendritic cells
- lymphocytes- class of wbc
Ex: natural killer cells (NK
cells), T cells, B cells; are predominantly found in the lymph.
For lymphocytes, during development
B cells stay in the …
T cells migrate to the..
bone marrow, thymus
Difference between T cells and B cells?
cells directly attack infected or cancerous cells, while B cells produce antibodies to neutralize pathogens and mark them for destruction.
What are complement?
Nonspecific group of proteins found in the blood plasma that forms a membrane attack complex that kills cells by
creating holes in the membrane
RNA interference (RNAi)
Cellular mechanism, destroys viral dsRNA, inhibits virus life cycle.
Natural killer (NK) cells
(lymphocytes, not phagocytes)
Can be activated by interferon
-Secrete perforin: creates pores in target cell, ruptures infected cells
-Secrete enzymes to degrade DNA, trigger apoptosis (programmed cell death)
