Exam II Microbiology: Chapter 11 Flashcards
What is in a state of dynamic equilibrium with microorganisms
The human body
Listed below are:
- Old age and extreme youth (infancy, prematurity)
- Genetic defects in immunity and acquired defects in immunity (AIDS)
- Surgery and organ transplants
- Underlying disease: cancer, liver malfunction, diabetes
- Chemotherapy/immunosuppressive drugs
- Physical and mental stress
- Pregnancy
- Other infections
Factors that weaken host defenses and increase susceptibility
A microbe whose relationship with its host is parasitic and results in infection and disease is called?
Pathogen
Disruption of a tissue or organ caused by microbes and their products is called?
Infectious disease
Portal of Entry – “Getting in” Adherence or Attachment – “Staying in” Defeating host defenses Damaging the host Exiting the host and transmission to the next host
Steps to causing infections
Any deviation from health is called?
Disease
The route that a microbe takes to enter the tissues of the body to initiate an infection
Portal of entry
Microbe originating from a source outside the body from the environment or another person or animal
Exogenous
Microbe already existing on or in the body – normal biota or a previously silent infection
Endogenous
What is capable of causing disease in healthy persons with normal immune defenses?
Primary pathogens
True / False
If certain pathogens enter the “wrong” portal, they will not be infectious
True
What can cause disease when the host’s defenses are compromised or when they become established in a part of the body that is not natural to them or when normal flora is destroyed?
Opportunistic pathogens
The degree of pathogenicity
-Is reflected by the relative severity of a disease caused by a particular microbe
Virulence
Virulence of a microbe is determined by its ability to:
- Establish itself in a host
2. Cause damage
Any characteristic or structure of the microbe contributes to its ability to establish itself in the host and cause damage is referred to as:
Virulence factor
The minimum number of microbes necessary to cause an infection to proceed is called?
Infectious Dose
ID or ID50
The number of microbes required to cause infection in 50% of test subjects is “technically” called:
Infectious Dose
ID or ID50
ID for rickettsia is a single cell
Rocky Mountain Spotted Fever
ID for tuberculosis and ________ about 10 cells.
giardiasisis
True / False
ID for E. coli is 100 cells
True
Microbes can use _________ to adhere (STAY IN) to the host
Fimbriae
Pili (since they help form biofilms)
Surface proteins
Adhesive slime layers or capsules
Viruses attach by specialized receptors
Parasitic worms fastened by suckers, hooks, and barbs
- Respiratory mucous membranes (most common since we have to breath continuously)
- Gastrointestinal mucous membranes (second most common since we have to eat or drink regularly)
- Genitourinary mucous membranes
- Parenteral portal of entry (broken skin)
- Intact skin (least common – very few microbes use this portal of entry)
The five portals of entry
Host cells that engulf and destroy pathogens by means of enzymes and antimicrobial chemicals are called?
Phagocytes
____________ makes it difficult to for phagocytes to engulf microbes
Extracellular capsule
Step Three: Surviving Host Defenses
____________ has a waxy wall (mycolic acid) can cannot be digested by the lysosome and can live inside a phagocyte
Mycobacterium
Step Three: Surviving Host Defenses
What kills phagocytes outright?
Leukocidins
Step Three: Surviving Host Defenses
Three ways that microorganisms cause damage to their host:
- Direct damage (example – viruses lysing host cells)
- Through the action of enzymes
- Through the action of toxins
Accumulated damage due to pathogens leading to cell and tissue death
Necrosis
Microbes eventually settle in a particular target organ and cause direct damage at the site is called?
Direct Damage
What are simply adaptations a microbe uses to establish itself in a host?
Virulence factors
What are enzymes secreted by microbes that break down and inflict damage on tissues?
Exoenzymes
What dissolves the host’s defense barriers to promote the spread of disease to other tissues?
Exoenzymes
What exoenzyme digests the protective coating on mucous membranes?
Mucinase
What exoenzyme digests the ground substance that cements animal cells together?
Hyaluronidase
What exoenzyme causes clotting of blood or plasma?
Coagulase
What exoenzyme dissolves fibrin clots?
Kinase
What exoenzyme disrupts the cytoplasmic membrane of red blood cells?
Hemolysins
What are the three types of hemolysis that can result from the production (or no production) of hemolysins?
- Gamma hemolysis
- Alpha hemolysis
- Beta hemolysis