3. Nonspecific Defenses and Inflammation

Question 1

Why is the skin considered both a physical and a chemical barrier?

Answer 1

Skin provides a protective barrier over the entire surface of the body to inhibit the entry of microbes = physical barrier. There are also secretions of sweat glands and sebaceous glands in the skin that secrete lactic acids and fatty acids which lower pH inhibiting microbial growth = chemical barrier.

Question 2

Where is lysozyme found, and how does it act as a chemical barrier?

Answer 2

• found in tears, saliva, and mucous

- it is an enzyme that lyses cell walls of certain bacteria = chemical barrier

Question 3

What is the effect of histamine in the inflammatory response?

Answer 3

• a vasoactive mediator released from mast cells and basophils. Its effects are vasodilation and increase in vasopermeability

Question 4

What is the role of cytokines in inflammation?

Answer 4

• induce increased vascular permeability, coagulation, expression of adhesion molecules

3 major inflammatory cytokines = Interleukin-1, interleukin-6, and Tumor Necrosis Factor alpha

Question 5

What are selectins and integrins?

Answer 5

Selectins = a cell surface protein on vessal walls of endothelial cells that mediate initial binding of leukocytes and subsequent rolling down the vessel wall.

Integrins = cell surface proteins on wbc that strengthen binding of leukocytes by causing them to spread on vessel wall

Question 6

What is chemotaxis, and how is it initiated?

Answer 6

• the migration of wbc’s through the vessels to the site of inflammation
• attracted by products of bacteria, wbc, and complement

Question 7

What is the order of migration of various cell types to the site of inflammation?

Answer 7

in 30 - 60 min 1. PMN’s (polymorphonuclear cells) = neutrophils, eos, and basos
in 4-5 hours 2. monocytes
in Few days 3. lymphocytes and plasma cells

Question 8

Which acute phase reactant is the most sensitive indicator of inflammation?

Answer 8

C- reactive protein