non-specific defences (external) Flashcards
1
Q
what do external defences do?
A
- stop pathogens and foreign particles from entering
- first line in defence
2
Q
what are the 8 external defenses?
A
1) skin
2) mucus
3) hairs
4) cilia
5) acids
6) lysozome
7) cerumen
8) movement of fluid
3
Q
how does the skin work as an external defense?
A
- Effective barrier covering outside of body
- Stops micro-organism entering
- Opening have special protection
- Huge numbers of bacteria live on skin
- Sebum = oily secretion produced by oil glands = contains substances that kill pathogenic bacteria
- Sweat = contains fatty acids & salts = prevent growth of many micro-organisms
4
Q
how does mucus work as an external defense?
A
- membranes line cavities that open to the exterior = secrete mucus
- trap particles
- inhibits entry of micro-organisms to organs
- digestive, urinary, reproductive tracts all protected
5
Q
how do hairs work as an external defense?
A
- found in nasal cavity + ears
- trap up to 90% of inhaled particles
6
Q
how do cilia work as an external defense?
A
- tiny hairlike projections from cells
- have a beating motion
- moves particles to exits to be removed
7
Q
how do acids work as an external defense?
A
- stomach juices
- kills consumed bacteria
- vagina = acid secretions that reduce micro-organism growth
- urine and sweat are also acidic
8
Q
how does lysozyme work as an external defense?
A
- enzyme that kills bacteria
- eyes are protected by tears flushing
- found in saliva, sweat, secretions of nose + tissue fluid
9
Q
how does cerumen work as an external defence?
A
- acidic
- contains lysozyme
- ear wax
- protects ear of infection
10
Q
how does the movement of fluid work as an external defence?
A
- flushin action keeps area
- urine through the urethra
- prevents bacterial growth
- stops bacteria breaching certain organs
11
Q
what are the 4 protective reflexes?
A
- sneezing
- coughing
- vomiting
- diarrhoea
12
Q
define a reflex
A
- automatic, involuntary response to a stimulus
