M4 - Immunity Physical Defenses

Question 1

What is a pathogen

Answer 1

A pathogen is any organism which causes disease
Communicable diseases are always caused by pathogens

Question 2

Pathogen examples

Answer 2

Bacteria - tuberculosis
Virus - HIV, influenza
Protoctist - plasmodium causes malaria
Fungi - athletes foot

Question 3

Human body primary/non-specific defenses

Answer 3

• lysozymes which kill bacteria
• Skin is physical barrier - if wounded, repaired by outer layer of skin cells - opening fuses together by formation of collagen fibres
• blood clots form when blood vessels damaged
• trachea has goblet cells which trap pathogens and ciliates epithelial cells sweep towards stomach
• damage of tissue becomes inflamed - releases histamines which causes vasodilation increases blood flow and white blood cells arrive quicker

Question 4

Physical plant defences

Answer 4

• Waxy cuticle on a leaf’s surface provides physical barrier against entry of pathogens
• Past the waxy cuticle is cell wall - physical barrier
• of pathogens invade, plants release callouses between cell wall and plasma membrane, making it harder for pathogens to enter

Question 5

Plant chemical defences

Answer 5

• some plants produce antibiotic or fungicidal compounds - kill or inhibit growth of bacteria and fungi
• produce insecticides to reduce infection by viruses transmitted by insects