10.2 the first line of defence

Question 1

what is the body’s first line of defence?

Answer 1

1. consists of non-specific immune responses that are innate
2. prevents pathogens from entering the body through physical and chemical barriers

Question 2

what is the body’s physical barrier?

Answer 2

skin: pathogens cannot enter the body through the skin unless there are breaks in the surface.
- also produces chemical barriers like sebum and sweat, they kill microorganisms before they enter the body.
cilia: pushes mucus with trapped pathogens away from susceptible tissues.

Question 3

what are the chemical barriers of the body?

Answer 3

1. tears: protect the eyes. contains lysozyme enzyme that breaks down bacterial cell walls. also physically washes away pathogens from the eyes.
2. saliva and mucus also contain lysozyme
3. mucus and wax trap pathogens that are not killed by the enzymes in tears and sweat.
4. acids: stomach acid lowers the pH of the internal environment, therefore a low pH will denature pathogenic proteins and kill pathogens.

Question 4

what are the additional barriers of the body?

Answer 4

1. urine: during urination, the flow of urine flushes pathogens out of the body (urinary tract and bladder).
2. natural flora: beneficial bacteria that actively compete with pathogenic microorganisms for space and resources.