Infectious Diseases Flashcards
Pathogens
Microorganisms that are capable of causing disease
True Pathogen
Ingectious agent that causes disease in virtually any susceptible host
Opportunistic Pathogen
Potentially infectious agents that rearely cause disease in individuals with healthy immune systems
Infection
Results when a pathogen invades and begins growing within a host
Disease
Results only if as a consequence of the invasion and growth of a pathogen, tissue function is impaired
Infectious disease caused by
invasion of host whose activities harm the host’s tissues and can be transmitted to other individuals
Infectious
Easily transmitted
Virulent
refers to the ability to cause disease (clinical disease)
very contagious
easy transmitted
not very virulent
not very likely to cause disease
4 things to cause of disease
- Enter the body
- Adhere to specific host cells
- invade and colonize host tissues
- Inflict damage on those tissues
What is disease damage often due to?
production of toxins or destructive enzymes by the pathogen
Nonspecific Mechanisms
Body’s primary defense against disease
- anatomical barriers, physiological barriers and normal flora, natural openings, blood
lysozyme
bacteria that breaks down bacterial cell walls (in saliva)
phagocytic
kill bacteria and viruses
Specific Mechanisms
immune response that enables the body to target particular pathogens
Lymphocytes
Specialized white blood cells
2 types of lymphocytes
T-cells - produced by lymphocytes in the thymus gland
B-cells - Produced by lymphocytes in bone marrow
Mall-mediated response
involves t-cells. Responsible for directly destroying body cells infected with a virus or activating other immune cells to be more efficient microbe killers
antibody-mediated response
involves both t-cells and (memory) b-cells
destructiong of invading pathogens and elimination of toxins
Macrophage
phagocytic cells
antigens
proteins on the surface of pathogens that elicit an immune response from the pathogen on surface
lymphokines
signal molecules
memory B-cells
can recognize antigens so quickly that an agent is not able to grow enough to cause disease
vaccination
provides ways to artifically create more memory B-cells
6 major types of microbes that cause infectious disease
- bacteria
- viruses
- fungi
- protozoa
- helminths
- prions
Bacteria
unicellular, prokartyotic organisms with no organized internal membranous structures (nuclei, mitochondria or lysosomes)
- binary fission
- doubles stranded DNA
aerobes
require oxygen
anaerobes
don’t need oxygen or can’t tolerate
facultatic anaerobes
can grow with or without oxygen
Gram negative
appear pink
Gram positive
appear purple
Viruses
not organisms
- composed of viral genome od nucleic acid that is surrounded by a protein coat called a capsid.
- many that infect animals surrounded by an outer lipid layer from host cell membrane as they leave the cell
- can be single stranded (RNA) or double stranded (DNA)
budding virus process
weakens but doesn’t destroy the cell
Rhinoviruses
cause most common colds
Retroviruses
causes AIDS and several types of cancer
Fungi
- eukaryotic (has nucleus
- heterotrphic (eats to live)
- chitin based cell walls
- reproduction through spores
Protozoa
- unicellular
- heterotrophic
- eukaryotes
- no cell walls
- capable of rapid and flexible movements
- acquired throguh conatminated food or water or by the bite of an infected arthropod such as mosquito.
Helminths
- simple invertebrate animals
- multicellular and will have differenticiated tissues
- difficult to treat
- drugs that kill helminths are frequently toxic to human cells
Helminths - Schistosoma
a flat worm that causes the mild disease, swimmer’s itch in the US
Helminths - trichinella spiralis
trichinosis
Prions
infectious protein particles that cause degenerative disorders of the central nervous system
- frequently result in brain tissue that is riddled with holes
- infection by eating infected tissue, or tissue transplants
