Question

Note the following
(A) Skin (B)Phagocytes (C)B-cells (D)Inflammation (E)Antibodies (F) T-cells (G)Fever (H)Complementary proteins (I)NK cells (J) Secretions
Identify the factors involved in the second line of defence.
A. (B) (D) (G) (H) and (I)
B. (B) (C) (E) and (I)
C. (D) (F) (H) and (J)
D. (C) (E) (G) and (H)

Answer 1

The second line of defence is nonspecific resistance that usually kills attackers without attacking particular individuals.

Complete Answer:
- Innate immune response, which has two main attributes, is the second layer of defence against pathogenic invasion:
1. It is non-specific (it does not distinguish between particular microorganisms)
2. It is non-adaptive (each time generates the same answer-in other words, it does not have memory)
- The innate immune system's cellular defences identify the cell types used along with the processes initiated by these cells.
- Inflammation (by mast cells), phagocytosis, fever and coagulation (by platelets) are included in these defences.

Inflammation: The inflammatory response is the way the body responds when cells are damaged by pathogens. When tissue damage occurs, a chemical called histamine is released by mast cells, causing local vasodilation and increased capillary permeability. To combat the infection, it also activates chemotactic variables that recruit wandering macrophages (phagocytes) to the damage site. Although inflammation is required to allow the access of immune cells to infected tissue, redness , swelling, heat and pain are side effects. It can be either short-term (acute) or long-term ( chronic) inflammation.

Phagocytosis: Phagocytic leukocytes (macrophages) circulate in the blood, but in response to infection they may pass into body tissue (extravasation). Because of the release of chemicals (such as histamine) from damaged body cells, they focus on sites of infection. Pathogens are engulfed and then fuse as cellular extensions (pseudopodia) surround the pathogen, sequestering it in an internal vesicle. To digest the pathogen, the vesicle can then fuse with the lysosome. In order to help promote antibody development, some of the pathogenic antigenic fragments may be presented on the surface of the macrophage. This endocytosis process is dubbed phagocytosis ('cell-eating').

Fever: Fever is an abnormally elevated infection-related body temperature and is caused by the release of prostaglandins. By growing the growth rate of pathogens (via the inactivation of enzymes and toxins needed by the invader), fever may help fight infection. It can also increase body cell metabolic activity and activate heat shock proteins to improve the overall immune response. Fever can be effective up to a certain extent, but it can destroy the body's own enzymes beyond a tolerable level.

Complementary proteins: Macrophages, monocytes and other body cells (particularly liver cells) produce complementary proteins. These proteins are usually inactive in the blood, but they cause a cascade of reactions that help protect the body in response to immune activation.In the following ways, activation of the complement system can provide protection:
Assisting in the elimination of pathogenic species by destroying cell membranes. Attracting phagocytes to the infection site (chemotaxis). Assisting in the detection of pathogens (opsonization).

Interferons: Interferons are a particular cytokine class that protects against viruses and tumour cells.
Infected cells release interferons which alert the surrounding cells (e.g. by activating antiviral agents) to reduce their susceptibility to infection. Interferons also recruit natural killer cells (NK cells) that target infected cells and kill them.

The correct answer is option A, (B) (D) (G) (H) and (I).

Note: The second line of defence becomes active if the pathogens are able to get through the first line of defence, for example, through a cut in your skin, and an infection occurs. The immune system targets these pathogens in a series of steps called the immune response.