Week 1- Infections and Immunity Flashcards
what is the difference between gram positive and gram negative bacteria?
Positive- singles cell membrane
Negative- two cell membranes and more resistant to antibiotics
What are some of the RNA viruses?
Hepititis, Flu and HIV
What are some examples of DNA viruses?
Varicella
Hepatitis b
What is virulence?
the degree of pathogenicity- how fast it makes people sick and how sick and how large the infectious dose is.
What are the stages of infection that a pathogen must go through?
- Infectious dose of pathogen penetrate the hosts defensive barrier
-Micro-organisms enter sterol environment of hosts tissue
Target tissue and cause disease - Leave the host through exit portal to infect another host
What is the first line non-specific defence?
Skin, mucous membranes, chemicals
What is the non-specific second line of impunity defence?
Phagocytes, complement interferon, inflammation and fever
what are the third line specific immune defences that the body has?
Lymphocytes and antibodies
What steps must a pathogen undergo to infect a host?
Enter body- evade external barriers
Multiplication- Use body to increase numbers
Local or general speed in body- avoid phagocytes
Damage body- Evade immune and other defences to cause tissue damage
-Shed/exit- leave body in sufficient numbers to new hosts
What are Exotoxins?
Proteins that are produced in pathogenic bacteria, most commonly in gram-positive that are then related after lysis and cause chemical damage to cells and tissues.
What are Endotoxins?
Lipid portions of outer membranes of mainly gram-negative bacterial that are liberated when the cells are lysed and cell wall breaks apart. These then cause chemical damage to cells and tissue
What changes can viruses cause in infected cells?
Cell swelling and bursting
cell fusion
carcinogenic changes
What is the chain of infection?
Infectious agent resivour portal of exit mode of transmission portal of entry susceptible host
What are the phases of progression of disease?
Incubation period- pathogen reproduces to sufficient numbers
Prodromal period- onset of some symptoms
Period of illness- most severe signs and symptoms
Period of recovery- deciding of sings and symptoms
Period of convalescence- disease is gone
What is a latent infection?
Where there is an initial infection and the virus move subsequently into the dorsal root ganglion and remain indefinitely. Later if there is immune depression there can be a reactivation of the virus
What is a chronic infection?
After initial infection, with or without symptoms the virus may remain in the body which can become deadly later.
What are the two internal defences agains infection?
Innate internal defences- Inflammatory response carried out by phagocytes within hours
Adaptive internal defences- immune response by lymphocytes carried out over a few days
What is an antigen?
Large fringe chemical that is precent on the outside of virus/bacteria/microbes stimulates an immune response
What are antibodies
Immunoglobulin proteins made by B-lymphocytes after contact with a specific (lock and key) antigen to inactive them through clumping them together and signal them for destruction
What are the three types of cells that T-lymphoctes can transform into?
T-helper cells- help to produce antibodies with the B-cells
Cytotoxic T cells- able to destroy pathogen cells
T-memory cells remain in circulation in case of future infection
What is active immunity?
Antibodies proceeded by a persons body
- Natural- pathogens enter the body in a natural manner
- Artificial- vaccines
What is passive immunity?
Antibodies from another organism enter a persons body
Natural- cross from mother to baby
Artificial- injected into another person
What is heard immunity?
Group immunity at a population level. Where the proportion of the population are immune to the disease so the disease is less likely to spread and come into contact with susceptible individuals.
What are some common side effects of vaccines?
Local heat, swelling, pain, fever, chills, headache
Rarely anaphylaxis
