Topic 6.6: Could the infections have been prevented? (Preventing entry of pathogens) Flashcards
What is the skin’s outer layer called?
Keratin
Where can microorganisms enter? What reduces the number of microorganism gaining access?
Through any wounds.
Blood clotting seals the wounds thus reduces the number of microorganisms gaining access.
What lives on the skin surface?
Large number of microbes called skin flora.
Skin flora occur naturally on the skin surface and are well adapted to the environment there
How is skin flora effective in preventing entry of pathogens?
Prevent colonization by other bacteria.
Why are other bacteria not so well suited to the conditions created?
Excreted chemicals such as urea and fatty acids.
Conditions created by salty sweats.
What lines the airways and gut?
Mucous membranes
Why are mucous membranes favorable for bacterial growth?
Lack any keratin layer, surface is always moist
Makes it favorable for bacterial growth.
How does the action of mucus and cilia help stop entry of microbes to the lungs?
The mucus secreted by goblet cells in the trachea and bronchi, traps microbes and other particles; then beating cilia carry the mucus up to the throat whether it is swallowed.
How does the enzyme lysozyme kill bacteria?
Secretions of this enzyme in eyes, mouth and nose help break down the bacterial cell walls causing the cell to burst.
How is hydrochloric acid released?
Gastric juices secreted by gastric glands in the stomach walls contain hydrochloric acid.
What is HCl’s pH?
Less than 2.0
Kills most bacteria with food
Optimum pH for the digestive enzyme pepsin which is also secreted in the gastric juices.
Where are gut flora found?
Small and large intestines.
Why do the natural flora benefit from living within the gut?
Conditions are ideal: warm, moist and with plentiful food supplies.
Why does the host (us) benefit from their presence called? Why do we benefit?
Mutualistic relationship.
Bacteria aid in digestive process
Competitvely exclude pathogenic bacteria
Compete with pathogens for food and space
Bacteria secrete chemicals such as lactic acid which are useful in the defense against pathogens.
