Question

List the names of five parts of your first line of defense IN DETAIL.

Answer 1

First line of defence is innate immunity.

INNATE IMMUNITY
Innate or natural immunity is the inborn capacity of the
body to offer resistance to pathogens and their toxic
products. It is due to genetic and constitutional make up
of an individual.
It may be specific (against a particular organism) or
non-specific.
Mechanisms of innate immunity
1. Mechanical barrier against invading microorganism is
provided by the intact skin and mucosa in the body.
2. Surface secretions constitute one of the important
mechanisms of innate immunity. These include:
Secretions from the sebaceous glands of skin contain
both saturated and unsaturated fatty acids that kill
many bacteria and fungi.
Saliva, constantly produced in the mouth cavity, has
an inhibitory effect on many micro-organisms.
Gastric juice and highly acidic environment of stom-
ach may hydrolyze microbial invaders.
Tears poured in the conjunctival sac mechanically
wash away the particles and a hydrolytic enzyme,
lysozyme present in the tears can destroy most of the
micro-organisms.
3. Humoral defence mechanisms provide innate immu-
nity by the non-specific microbicidal substances present
in the body fluids. A few examples are:
Lysozyme is found in high concentration in most tis-
sue fluids except cerebrospinal fluid, sweat and urine.It is a mucolytic enzyme which kills micro-organisms
by splitting sugars of the structural mucopeptide of
their cell wall.
Basic polypeptides containing non-specific microbi-
cidal activity include leukins, arginine and lysine con-
taining proteins protamine and histone.
Complements have lytic and several other effects on
the foreign substances .
Interferons are antiviral substances produced by the
cells stimulated by live or killed viruses. The α and β
interferons are part of the innate immunity.
4. Cellular mechanisms of defence, which provide non-
specific innate immunity are:
Phagocytes, i.e. neutrophils and the monocyte–
macrophage system cells constitute the most impor-
tant non-specific cellular defence against the invading
micro-organisms.
Natural killer (NK) cells refer to a subpopulation of lym-
phocytes which provide non-specific cellular defence
against viruses, tumour cells and other infected cells.
Eosinophil granules contain enzymes and toxic mol-
ecules that act against larvae of helminths.