Infiltration Of Neutrophils

Question 1

What is chemotaxis?

Answer 1

Directional movement towards a chemical along a conc gradient

Question 2

Name some examples of chemotaxins

Answer 2

Spilled blood, bacterial products, injured tissues, leukocyte products

Question 3

What is endotoxin?

Answer 3

A lipopolysaccharide from the outside of gram negative bacteria

Question 4

What is activation? (In infiltration of neutrophils)

Answer 4

1: chemotaxin binds to cell. 2: Na+ and Ca2+ rush into cell. 3: causes cell to reorganise cytoskeleton in direction of stimulus.

Question 5

What is margination?

Answer 5

This is where instead of neutrophils being in the centre of flow, they congregate at the edges. The neutrophils stick to the walls of venules and roll along, they then ‘get stuck’/adhese and then ‘crawl’ out of vessel.

Question 6

What molecules are involved in adhesion?

Answer 6

Selectins- when they roll. Integrins- when the stick. (Their number is increased by inflammatory response)

Question 7

What is diapedis?

Answer 7

When the neutrophils ‘dig’ their way out of a venule

Question 8

How does diapedis come about?

Answer 8

The neutrophils produce collagenase which digests the basement membrane and once in the extra-cellular space, they pull themselves along fibres.

Question 9

What is recognition/attachment of neutrophil infiltration?

Answer 9

Opsonins make it easier to recognise eg foreign body and phagocytose them

Question 10

What are the stages of phagocytosis?

Answer 10

Recognition, contact, engulf, internalisation, degranulation of phagosome.

Question 11

What stages are there in the infiltration of neutrophils?

Answer 11

Chemotaxis, Activation, Margination, Diapedis, Recognition/Attachment, Phagocytosis then killing mechanisms