Infectious Disease Flashcards
Infectious Disease
Diseases caused by pathogens (e.g. common cold).
Non-infectious Disease
Diseases caused by lifestyle, environmental or genetic factors (e.g. diabetes).
Contagious
The ability to spread from person to person.
Pathogen
Microbes able to cause disease.
Prions
Misfolded proteins able to trigger healthy proteins to misfold abnormally leading to brain damage (e.g. CJD)
Viruses
Genetic material surrounded by a coat of protein which requires the presence of a host cell to reproduce causing cell death (e.g. COVID-19).
Bacteria
Prokaryotic microorganisms which reproduce through binary fission and releases toxins causing tissue damage (e.g. Salmonella).
Fungi
Microorganisms which feed at the expense of a host organism and reproduce asexually by releasing spores that cause disease (e.g. Athlete’s foot).
Protists
Parasites which spread via vectors and enter the body causing disease (e.g. Malaria).
Disease Transmission
Direct Touch
Bodily Fluids
Airborne Particles
Contaminated Ingestion
Vectors
Medical Procedures
Adherence Factors
Enables pathogens to adhere to host cells (e.g. bacterial adhesins).
Invasion Factors
Enables pathogens to enter host cells (e.g. bacterial exoenzymes).
Capsules
Enables pathogens to avoid detection by the immune system (e.g. bacterial capsules).
Toxins
Enables pathogens to produce symptoms of disease within a host cell (e.g. bacterial toxins).
Lifecycle Changes
Enables pathogens to transmit between various host cells (e.g. blood flukes).
Innate Immune Response
Non-specific immune response present in all plants and animals to protect against pathogens by reducing the likelihood of disease and controlling the severity.
First Line of Defence
A system of barriers to prevent pathogens from entering the body.
Physical Barriers
Stops pathogens from entering the body by blocking or trapping them (e.g. skin).
Chemical Barriers
Kills pathogens before they can enter the body (e.g. stomach acid).
Second Line of Defence
A system of generalized responses to pathogens entering the body.
Inflammation
The accumulation of fluid, plasma proteins and leukocytes when tissue is damaged or infected.
Inflammation Response
Histamines are released from mast cells
Cytokines are released from injured cells
Vasodilation and increased permeability of blood vessels occur due to histamines
Neutrophils migrate towards the cytokines to kill pathogens
Phagocytes (macrophages) phagocytose pathogens and debris
Prostaglandin
A type of cytokine that increases the temperature of the body resulting in a fever.
Complement System
Proteins which circulate the blood inactively and are triggered to help kill pathogens.
Adaptive Immune System
Specific immune system which targets specific pathogens by recognizing and memorizing specific antigens and producing specific antibodies through humoral and cell-mediated immunity.
Humoral Immune Response
B-cells target pathogens in the body’s fluids by producing antibodies from plasma/effector cells which hunt and fight antigens through proliferation alongside memory B-cells which keep samples of the antigen to enhance immunity.
Role of Antibodies
Enhances phagocytosis through precipitation of dissolved antigens
Prevents adherence through neutralization and agglutination
Activates the complement system which leads to lysis of foreign cells
Cell-Mediated Immune Response
T-cells target pathogens in the body’s cells by helper T-cells recognizing antigens from antigen-presenting cell’s major histocompatibility complexes (e.g. macrophages/dendritic cells) utilizing their receptors and proliferating into memory T-cells and activating cytotoxic T-cells.
Cytotoxic T-cells
Proliferates into memory cytotoxic T-cells and destroys infected or defective cells by releasing cytotoxins which cause apoptosis.
Helper T-cells
Proliferates to create memory T-cells, activates B-cells and cytotoxic T-cells.
Passive Immunity
Antibodies are transferred from one organism to another. Lasts for a short time.
Natural: Placenta
Artificial: Antiserum
Active Immunity
Production of antibodies following exposure to antigens. Lasts for a long time.
Natural: Disease
Artificial: Vaccination
