physical and chemical barriers Flashcards
give an example of a physical barrier
skin
how can a pathogen pass a physical barrier?
through wounds
by an animal vector that pierces the skin
what additional defence does the skin have?
glands that produce secrete substances - lysozyme
what does lysozyme do?
breaks down the cell walls of some types of bacteria
why is skin a physical barrier?
pathogens have difficulty getting past it
why is lysozyme a chemical defence?
it reacts with substances in the pathogen which kills them or makes them inactive
where is lysomzyme secreted from?
tears(in eyes)
saliva(in mouth)
mucus - protects thinner surfaces of the body
what is mucus?
sticky secretion produced from cells lining openings - mouth and nose - that pathogens could use to enter the body
what gets trapped in mucus?
dust and pathogens
what are the cells that line the nose and tubes in the breathing system?
cilia
how are cilliated cells specialised and how is this helpful?
they move substances such as mucus across their surfaces
helps carry dust and pathogens away either out of the body or into the throat where they enter the digestive system
where does substances that you swallow pass down?
oesophagus (gullet) then into the stomach
what do some cells in the stomach produce and what does it reduce?
secrete hydrochloric acid
reduce pH to 2
what does the acidity of the stomach do to pathogens?
destroy them
name 2 STIs
HIV virus
chlamydia bacterium
