24 Questions
How do normal flora interfere with the growth of pathogens?
By competing for nutrients and producing substances that inhibit pathogen growth
What is contamination?
The presence of microorganisms on a living or non-living surface
What is the difference between infection and disease?
Infection occurs when microorganisms multiply in the host, while disease is the resulting harm or malfunction of the organ or body
What is pathogenicity?
The ability of a microorganism to produce disease
What is the difference between pathogenicity and virulence?
Pathogenicity is the ability to produce disease, while virulence is the intensity of the disease produced
What is an example of a microorganism with high virulence?
Mycobacteria tuberculosis
What is colonization?
The multiplication of microorganisms in or on the host body without inducing harmful effects
What is the relationship between contamination, colonization, and infection?
Contamination can lead to colonization, which can lead to infection
What is an opportunity for an organism to cause disease, especially when the host's defenses are weakened?
Failure of host defenses, e.g. AIDS
What can happen when normal microflora is disrupted, leading to an imbalance in the body's natural ecosystem?
Yeast growth due to inhibition of normal flora by antibiotics
What is the difference between infectious and non-infectious diseases?
Infectious diseases are caused by infectious agents, while non-infectious diseases are caused by any factor other than infectious agents
What is an example of a non-communicable infectious disease?
Infection by organisms in the environment, e.g. Tetanus
What is the main difference between communicable and non-communicable infectious diseases?
Communicable diseases can be transmitted from one host to another, while non-communicable diseases cannot
What is an example of a disease caused by an error in genetic information?
Inherited diseases
What is the term for a relationship between organisms where one benefits and the other is harmed?
Parasitism
What is the term for a relationship between organisms where one benefits and the other is not affected?
Commensalism
What is the incubation period in the context of infections?
The time between infection and the appearance of signs and symptoms, ranging from a few days to months or years.
What is the prodromal phase of infection?
A short period where non-specific symptoms appear.
What characterizes the acme of an infection?
The peak of the infection, often marked by fever due to the release of pyrogens.
What is the purpose of the convalescence period?
A recovery phase where symptoms disappear, and the body heals and regains strength.
What are sequelae, and how do they relate to infections?
Sequelae are long-term effects or complications that can occur after an infection, such as blindness or organ damage.
What is a communicable disease, and when can it be transferred?
A communicable disease can be transferred during the incubation period and during recovery from the disease.
What is the key difference between infection and disease?
Infection refers to the presence of a pathogen, while disease refers to the symptoms and harm caused by the pathogen.
What is the significance of the decline phase in the stages of infection?
The decline phase marks the point where host defenses and treatments overcome the pathogen, and symptoms are reduced.
Study Notes
Normal Flora and Pathogens
- Normal flora interfere with pathogen growth by competing for nutrients or producing substances that inhibit pathogen growth.
Contamination, Infection, and Disease
- Contamination: the presence of microorganisms on a living or non-living surface.
- Colonization: the multiplication of microorganisms on or in the host body without inducing harmful effects.
- Infection: the induction of destructive or harmful effects on host tissue as a result of microorganism multiplication in or invasion of that tissue.
- Disease: a disturbance in the health of the organ/body leading to its malfunction.
- The progression from contamination to colonization to infection can lead to disease.
Pathogenicity and Virulence
- Pathogenicity: the ability of an organism to produce a disease, dependent on its ability to invade the host, multiply, and avoid host defenses.
- Virulence: determines the intensity of disease produced by the pathogen.
- Virulence can increase due to factors such as failure of host defenses, introduction of the organism into unusual body sites, or disruption of normal microflora.
Kinds of Diseases
- Infectious diseases: caused by infectious agents (e.g., bacteria, viruses, fungi, protozoa, and helminths).
- Non-infectious diseases: caused by any factor other than infectious agents.
- Communicable infectious diseases: can be transmitted from one host to another (e.g., influenza, measles).
- Non-communicable infectious diseases: not transferred from a host to another, can result from infections by normal flora, ingestion of food poisoned by bacterial toxins, or infection by environmental organisms.
Classification of Diseases
- Inherited diseases: caused by errors in genetic information.
- Congenital diseases: present at birth (e.g., poliovirus leaving paralysis, some diseases leaving scars).
Stages of Infection
- Incubation period: the time between infection and appearance of signs and symptoms, during which the patient is contagious.
- Prodromal phase: a short period with non-specific symptoms, during which the patient is contagious.
- Invasive phase: full development of signs and symptoms, during which the patient is contagious.
- Decline phase: host defenses and treatments overcome the pathogen, symptoms are reduced, and the body functions gradually return to normal.
- Convalescence period: the recovery phase, during which symptoms disappear, and the body heals and regains strength.
This quiz explores the role of normal flora in preventing the growth of pathogens, including competing for nutrients and producing inhibitory substances. It also covers contamination, infection, and disease.
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