Chapter 14 Micro Flashcards
what is a pathogen?
disease causing microorganism
Infection means what?
colonization of the body by pathogens
disease
abnormal state which the body is not functioning normally
what is pathogenesis?
development of the disease
etiology can be defined as what?
the cause of a disease
Few microorganisms are pathogenic. True or false?
TRUE!
what is the importance of normal microbiota?
permanently colonize the host starting at birth and later through food and contact with others
how are microbiota studied and what is the benefit?
DNA sequencing to make microbiome.
Determining microbiome can help with specific syndrome or disease correlation
why might different types of bacteria colonize different parts of the body?
- Nutrient availability (secretion, excretions and dead cells
- physical and chemical factors (pH and temp)
- defenses of the host
- mechanical factors (chewing, flushing, mucus and cilia)
what are transient microbiota?
only present for a short period of time, typically coming from the environment and do not cause disease.
when can transient microbiota cause disease?
when it displaces the normal microbiota
list some factors that contribute to differing microbiota in each person:
age diet stress climate lifestyle occupation emotional state health status
where does normal microbiota reside?
skin conjunctiva nose throat mouth large intestine urinary tract reproductive system
normal microbiota of the skin:
most microbes do not become direct residents due to oil and sweat on skin’s surface. low moisture content
what is keratin’s role in the normal microbiota?
serves as barrier; low pH of skin inhibits many microbes
normal microbiota of conjunctiva:
contains nearly the same microbiota found on the skin’s surface
what are some defenses of the conjunctiva to prevent microbe colonization?
tears and blinking
normal microbiota of nose and throat:
microbial antagonism reduces potential pathogens from causing disease
what are some defenses of the nose and throat to prevent colonization?
nasal secretions kill and inhibit many microbes
mucus and ciliary action remove microbes
normal microbiota of the mouth:
moisture, warmth and constant presence of food make the mouth an ideal environment that supports large diverse microbial populations
what are some defenses of the mouth?
biting, chewing, tongue movements and salivary flow dislodge microbes
normal microbiota of the urinary and reproductive systems:
mucus and shedding of the lining prevent microbes from attaching
Flow removes microbes
cilia and mucus expel microbes from the cervix
what are defenses of the urinary and reproductive tract to prevent microbe colonization?
- acidity of the vagina inhibits or kills microbes
- urea and low pH of urine are antimicrobial
normal microbiota of the large intestine:
contains largest numbers of the resident microbiota in the body because of moisture and nutrients
what are defenses of the large intestine to prevent microbe colonization?
- mucus and regular shedding of the lining prevent many microbes from attaching to the lining of the GI tract
- mucosa produces several antimicrobial chemicals
microbial anatogonism
competition between microbes
how does the normal microbiota use microbial antagonism?
competing for nutrients
producing substances harmful to invaders
changing conditions such as pH and O2
explain germ free animals
raised in lab but have underdeveloped immune systems and are more susceptible to pathogenic infection
require more calories and vitamins than normal animals
what happens when germ free animals are repopulated with microbiota from obese animals?
they become obese
why are germ free animals used?
help investigate host microbe interactions that promote health
PRObiotics are described as what?
live microbes that are applied or ingested to the body for beneficial effects
PREbiotics are describes as what?
chemicals that selectively promote growth of beneficial bacteria
what is the purpose for the FMT (fecal microbiota transplant)?
process of transplantation of fecal bacteria from healthy donor to recipient, can help with C. diff
What are the three types of symbiosis?
commensalism, mutualism, parasitism
what is commensalism?
one organism benefits and the other is unaffected
Example: S. epidermia inhabit surface on skin
what is mutualism?
both organisms are benefiting
Example: E.coli: bacteria in the large intestine that synthesizes vitamin K and some B vitamins; they’re absorbed into the bloodstream and distributed for use by body cells. In exchange, the large intestine provides nutrients used by the bacteria, allowing them to survive
what is parasitism?
one organisms benefits at the expense of the other like pathogens
Example: influenza
opportunistic pathogens are what?
when pathogens that normally inhabit other areas gain access to other body sites it can be detrimental in immunocompromised people
what are the three ways normal microbiota protect the host?
- occupy niches that pathogens might occupy
- lower ph by producing acids
- produce bacteriocins that kill other bacteria
what does etiology mean?
the cause of diseases or conditions
what are Koch’s postulates?
- same pathogen must be present in every case of the disease
- pathogen must be isolated from the diseases host and grown in pure culture
- pathogen from pure culture must cause the disease when it is inoculated into healthy lab animal
- pathogen must be isolated from inoculated animal and must be shown to the original animal
why is paying attention to Koch’s postulates important?
correlation does not mean causation
what are some problems with Koch’s postulates?
- some organisms cannot be cultured on artificial media
- some diseases types can be caused by multiple different pathogens
- some pathogens cause multiple diseases
- some carriers are asymptomatic
- some pathogens cause symptoms or leave tell tale signs that no other pathogen can produce, implicating it in the disease
what are the 3 ways to classify infectious diseases?
- signs and symptoms
- syndromes
- contagious, communicable, noncommunicable
