Week 9 Flashcards
What are the 3 lines of defence?
1st
2nd
3rd
Briefly describe the first line of defence.
Non-specific so acts as a defence against any pathogen
Is the first line of defence specific?
No
What type of pathogens does the first line of defence act on?
All
Briefly describe the second line of defence.
Specific for bacteria and viruses.
Describe the specificity of the second line of defence
Specific to viruses and bacteria
What the of pathogens does the second line of defence act on?
Viruses and bacteria
Briefly describe the third line of defence
Specific for a particular pathogen
Describe the specificity of the third line of defence
Specific for a particular pathogen
What are innate defences against pathogens?
Mechanical barriers which prevent entry and help undergo phagocytosis.
If a pathogen manages to invade the body, what type of reaction occurs and why?
Inflammatory reaction to keep the infection contained.
What is the general purpose of an inflammatory reaction in the body?
To keep an infection localised and prevent its spread.
When is the first line of defence against pathogens present?
Constantly because it is innate (natural).
Is the first line of defence against pathogens physical or chemical?
Both
What is the first line of defence for the eyes and how does this work?
Lysozymes in the tears and other secretions dissolve pathogen cell walls.
How does the skin act as part of the first line of defence?
Acts as a physical barrier.
Produces antimicrobial fatty acids and is normal flora inhibits pathogen colonisation.
How does the stomach prevent pathogenic growth?
Has rapid changes in pH
How is colonisation of pathogens prevented in the urinary tract?
Flushing of the urinary tract.
How are pathogens expelled from the nose?
Removal of particles by rapid passage of air over cilia in the nasopharynx.
How are microorganisms prevented from entering the body via the trachea?
Microorganisms are suspended in the mucus and are moved out of the body by the cilia.
What prevents phagocytic colonisation in the lungs?
Mucus and phagocytes.
In the intestines, what prevents bacterial growth?
The normal bacterial flora.
What is the overall purpose of the second line of defence against pathogens?
Used to localise infection, neutralise toxins and repair tissue damage.
What is the third line of defence against pathogens mediated by?
Antibodies and cells
What are the cardinal signs of acute inflammation?
Redness. Swelling. Heat. Pain. (Loss of function).
What are the factors that transmission of pathogens depends on?
Number of microorganisms shed.
Microorganisms stability in the environment.
Number of microorganisms required to infect the new host.
What is a reservoir of infection?
The population of organisms or the specific environment in which an infectious pathogen naturally lives and reproduces, or upon which the pathogen primarily depends for its survival.
What must a disease have to persist in a community that is not it’s natural habitat?
A reservoir or continual source of organisms that are either living or non-living.
What are the types of disease reservoirs.
Human
Animal
Insect
Give examples of non-living disease reservoirs.
Soil
Water
Air
Food
What are zoonoses?
Diseases which can be transmitted between humans and animals.
Name some portals of exit for microorganisms from a human
Ear via ear wax.
Broken skin via blood.
Skin.
Anus via faeces.
Eyes via tears.
Nose via secretions.
Mouth via saliva.
Mammary glands in females via milk.
Vagina via discharge or blood.
Urethra via urine.
Seminal vesicles via semen and lubricating secretions.
What are the 3 categories of microorganism transmission ?
Contact transmission
Vehicle transmission
Vector transmission
What are the types of contact transmission for microorganisms?
Direct contact.
Indirect contact.
Droplet transmission.
How are pathogens spread via indirect contact ?
They are spread from one host to another via fomites.
What are fomites?
Inanimate objects that are used to transfer pathogens to a new host.
What are the sub-types of vehicle transmission of pathogens?
Airborne
Water borne
Food bone
What are the 2 types of vector transmission of pathogens ?
Biological vectors
Mechanical vectors
What are biological vectors?
They transmit pathogens and act as a host for multiplication.
Give some examples of biological vectors.
Insects, ticks and mites.
What are mechanical vectors of pathogens?
They are insects that carry pathogens passively.
What are the types of person-to-person transmission ?
Respiratory Salivary Venereal Faecal-oral Skin Blood
How are pathogens passed from person-to-person via the respiratory routes?
When people sneeze or cough particles containing the pathogen will be in each particle and will be transmitted to others.
When is respiratory person-to-person transmission of disease increased?
In crowded conditions
How are diseases spread person-to-person via the general route?
Generally spread as a result of mucosal contact.
How are faecal-oral measures of disease transmission reduced?
Adequate sewage disposal and purified water.
How are diseases spread via the faecal-oral route in more developed countries ?
Via food and fingers.
How are diseases spread via the faecal oral route in less developed countries ?
Via water and flies.
How are diseases spread via the skin?
Through shedding from the hair, skin and nails or direct contact.
Describe horizontal transmission of disease.
Exponential.
Most common in crowds.
When is horizontal disease transmission most common?
In crowds.
Give examples of vertical disease transmission.
Mother to baby through the placenta or at childbirth via the milk.
What is meant by systemic infection?
When the blood becomes infected.
Where in the body does mycobacterium tuberculosis infect?
The lungs.
How is mycobacterium tuberculosis spread?
Respiratory aerosols.
Where in the body does Neisseria Gonorrhoea infect?
The urogenital tract.
Where in the body does Vibrio Cholerae infect?
Gastrointestinal tract.
What is the portal of entry for vibrio cholera?
The mouth via contaminated food or water.
