Lecture 13 Flashcards
A condition in which pathogenic microorganisms penetrate host defenses, enter the tissues, and multiply
infection
- Cumulative effects of infection damage
- Disruption of tissues and organs
- Results in disease
pathologic state
Any deviation from health
disease
factors that cause disease
infections, diet, genetics, aging
Disruption of tissues or organs caused by microbes or their products
infectious disease
Large and diverse collection of microbes living on and in the body
normal biota
known as resident or indigenous biota
normal flora
- Include an array of bacteria, fungi, protozoa and viruses
- These organisms have a profound effect on human biology
normal biota
sites that harbor a known normal biota
- skin
- respiratory tract and lungs
- GI tract
- urethra
- genitalia
- ear canal
- eye
sterile sites of human body
- Influence the development of organs
- Prevent the overgrowth of harmful microorganisms
benefits of normal biota
- The general antagonistic effect “good” microbes have against intruder microorganisms
- Microbes in a steady, established relationship are unlikely to be displaced by incoming microbes
microbial antagonism
can influence many facets of your overall health.
intestinal biota
Differences in the gut microbiome have been preliminarily associated with differences in the risk for:
Heart disease Asthma Autism Rheumatoid arthritis Even thoughts, moods, and propensity for mental illness
factors that weaken host defenses and increase susceptibility to infection
- age
- AIDS/genetic defects
- surgery
cancer, liver malfunction, diabetes - chemotherapy
- physical and mental stress
- other infections
- Caused by biota already in the body
- Can occur when normal biota is introduced to a site that was previously sterile
endogenous infections
example of endogenous infections
Escherichia coli entering the bladder, resulting in a UTI
A growing number of doctors and scientists believe fetuses are seeded with normal microbiota
in utero
table 13.4
- A microbe whose relationship with its host is parasitic
- Results in infection and disease
- Type and severity of infection depend on both the pathogenicity of the organism and the condition of the host
pathogen
Describes an organism’s potential to cause infection or disease
pathogenicity
Capable of causing disease in healthy persons with normal immune defenses
true pathogens
Cause disease when:
- The host’s defenses are compromised
- When they become established in a part of the body that is not natural to them
opportunistic pathogens
The relative severity of the disease caused by a particular microorganism
virulence
Any characteristic or structure of the microbe that contributes to toxin production or induction of an injurious host response
virulence factors
steps to infection
- entry
- attach to the host
- surviving host defenses
- disease
A characteristic route taken by a microbe to initiate infection
Usually through skin or mucous membranes
portal of entry
originating outside the body
exogenous
already existing in the body
endogenous
sites of entry in skin
nicks
abrasions
punctures
conjunctiva
The Gastrointestinal Tract as Portal
food, drink, or other ingested substances (adapted to survive digestive enzymes and abrupt pH changes)
gateways to the respiratory tract
oral cavity
nasal cavity
Pathogens transmitted by sexual means
Account for 4% of infections worldwide
13 million new cases in the U.S. each year
STI’s
- Formed by maternal and fetal tissues
- Separates the blood of the developing fetus from that of the mother
- Permits diffusion of dissolved nutrients and gases to the fetus
placenta
how are pathogens infected during pregnancy and birth
- cross the placenta and are spread by the umbilical vein into the fetal tissues.
- are transmitted perinatally as the child passes through the birth canal.
common infections of the fetus and neonate.
TORCH
TORCH
Toxoplasmosis Other diseases: syphilis, coxsackievirus, varicella-zoster virus, AIDS, chlamydia Rubella Cytomegalovirus Herpes simplex virus
a minimum number of microbes required for an infection to proceed
infectious dose
White blood cells that engulf and destroy pathogens by means of enzymes and antimicrobial chemicals
phagocytes
Virulence factor used by pathogens to avoid phagocytes
Circumvent some part of the phagocytic process
antiphagocytic factors