Infectious disease - responses to pathogens

Question 1

response of a named Australian plant to a named pathogen

Answer 1

THE EUCALYPTUS CALOPHYLLA

The named Australian Plant - eucalyptus callophylla
The named pathogen - phytophthora cinnamoni is a soil-borne pathogen that attacks root and collar of several Australian plant species.

Response - When exposed to the water mould the pathogen produces extra lignin in the root cells and the pathogen is unable to penetrate the cells and cause harm.

Question 2

brief description of the lines of defense

Answer 2

1. The bodies 1st line of defence against pathogens consists of barriers to entry. These may be physical (skin), chemical (tears), or biological (sphincters).
2. When a barrier is breached the 2nd line of defence is activated – it involves a non-specific chemical response and is characterised by the process of inflammation.
3. Adaptive immunity is the 3rd line of defence that is a specific defence mechanism consisting of specialised cells that act if the pathogen persists.

Question 3

First line of defense - physical barriers example

Answer 3

Skin: Dry, waterproof surface. Limits pathogen growth and prevents entry. Secretions from sebaceous glands inhibit pathogen growth

Question 4

First line of defense - chemical barriers example

Answer 4

Anti-microbial secretions from skin, stomach wall, mucous membranes, and vagina are acidic with high PH levels that reduce microbe growth and kill microbes.

Question 5

Chemical responses

Answer 5

FIP
Fever - The body’s temperature begins to rise as a result of the other chemical responses and this slows down/kills the production of pathogens.

Inflammation - When the pathogen breaks the first line of defense, mast cells release histamine that causes dilation of the blood vessels (vasodilation). This increases the concentration of phagocytes allowing for phagocytosis and increases the temperature making the environment inhospitable.

Phagocytosis - Inflammation attracts phagocytes that engulf and breakdown the pathogen.

Question 6

Cell-mediated response

Answer 6

Effective against intracellular pathogens and predominantly T-cells

Question 7

Antibody-mediated (Humoural) response

Answer 7

Extracellular pathogens (in body fluids) and predominantly B-cells