DEFENCE MECHANISMS Flashcards

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1
Q

what is a pathogen

A

microorganism with the potential to cause disease

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2
Q

what is an infection

A

invasion and multiplication of pathogenic microbes

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3
Q

what is disease

A

when infection causes damage to the individuals vital functions

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4
Q

what is the first line of defense

A

prevents pathogens from entering the body

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5
Q

first line of defense examples

A

skin - physical barrier. if broken platelets form a scab acting as a physical barrier
skin - chemical barrier - lysozymes found in tears / mucus destroys peptidoglycan in cell walls of bacteria
stomach - hcl destroys bacteria
cilia - beat to move mucus up and out

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6
Q

which pathogens can pass through the first line of defense

A

malaria
bubonic plague
influenza

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7
Q

cell recognition

A

self - body’s own cells and molecules
non-self - any foreign material / cell

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8
Q

what is an antigen

A

molecule / protein that stimulates an immune response and is found on the surface

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9
Q

what can antigens recognise

A

pathogens
non-self material
toxins
tumor cells

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10
Q

describe phagocytosis

A

1.Pathogen is recognised as foreign
2. Phagocyte moves to it (chemoattractants
present)
3. Phagocyte attaches to pathogen by surface
receptors
4. Pathogen is engulfed by phagocyte (endocytosis)
5. A phagosome (membrane bound vesicle
containing pathogen) forms inside phagocyte
6. Lysosomes (with hydrolytic enzymes) fuse into
phagosome & release lysozymes into phagosome
7. Pathogen is completely digested- harmless
products excreted / used
8. Phagocyte displays antigenic components on its
external surface (antigen presentation), for

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11
Q

effects of phagocytosis

A

causes inflammation at infection site
swollen area contains dead bacteria and phagocytes (pus)
damaged tissues release histamines causing dilation of blood vessels
increasing rate of antibody and WBC delivery to site of infection

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