2: CELLS - NON-SPECIFIC IMMUNE RESPONSE

Question 1

What are the 2 types of primary defenses?

Answer 1

• physical barriers
• chemical barriers

Question 2

What are some examples of physical barriers?

Answer 2

• skin
• eyelashes
• mucus membranes and cilia
• reflexes (sneezing/coughing/blinking)

Question 3

What are some examples of chemical barriers?

Answer 3

• tears (contain lysozymes which are antibacterial and destroy cell walls)
• sebum (oily substance on skin made up of fatty acids which is antimicrobial)
• acids (eg: HCL in the stomach)

Question 4

What are the 3 secondary defences?

Answer 4

• blood clotting
• phagocytosis
• inflammatory response

Question 5

Why does blood clot?

Answer 5

damaged blood vessels sealed with localised clot formation to prevent significant bleeding

Question 6

What is phagocytosis?

Answer 6

the process of phagocytes ingesting pathogens and subsequently destroying the ingested pathogens by lysozymes

Question 7

Describe the process of phagocytosis?

Answer 7

• the phagocyte ingests the pathogen
• a membrane called a phagocytic vacuole/phagosome forms around the pathogen
• a lysosome (containing lysozymes) moves towards the phagocytic vacuole
• the lysosome fuses with the phagocytic vacuole/phagosome to form a phagolysosome
• lysozymes hydrolyse the pathogen
• digested pathogen released by exocytosis as soluble debris

Question 8

Describe inflammatory response

Answer 8

• aims to localise and eliminate the pathogen and remove damaged tissue components so that the body can begin to heal
• chemicals cause blood vessels to leak fluid into the tissues, causing swelling. This helps isolate the foreign substance from further contact with body tissues

Question 9

What are the differences between neutrophils and monocytes?

Answer 9

• neutrophils have lobed nuclei whilst monocytes have bean shaped nuclei
• neutrophils are granulocytes (have granules containing proteins) whereas monocytes are agranulocytes (don’t have granules)