Human Health and Disease 2 Flashcards
what is immunity
This overall ability of the host to fight the disease-causing organisms,
conferred by the immune system is called immunity.
what is innnate immunity
Innate immunity is non-specific type of defence, that is present at the time of birth. This is accomplished by providing different types of barriers to the entry of the foreign agents into our body.
4 types of barriers provided by innate immunity
(i) Physical barriers : Skin on our body is the main barrier which
prevents entry of the micro-organisms. Mucus coating of the
epithelium lining the respiratory, gastrointestinal and urogenital
tracts also help in trapping microbes entering our body.
(ii) Physiological barriers : Acid in the stomach, saliva in the mouth, tears from eyes–all prevent microbial growth.
(iii) Cellular barriers : Certain types of leukocytes (WBC) of our body like polymorpho-nuclear leukocytes (PMNL-neutrophils) and monocytes and natural killer (type of lymphocytes) in the blood as well as macrophages in tissues can phagocytose and destroy
microbes.
(iv) Cytokine barriers : Virus-infected cells secrete proteins called
interferons which protect non-infected cells from further viral
infection.
what is meant by acquired immunity? explain wrt primary and anamnestic response
Acquired immunity, on the other hand is pathogen specific. It is
characterised by memory. This means when our body encounters a
pathogen for the first time it produces a response called primary
response which is of low intensity. Subsequent encounter with the same
pathogen elicits a highly intensified secondary or anamnestic response.
This is ascribed to the fact that our body appears to have memory of the
first encounter.
The primary and secondary
immune responses are
carried out with the help
of two special types of
lymphocytes present in our
blood, i.e., B-lymphocytes and
T-lymphocytes.
who secretes antibodies
The B-lymphocytes produce an
army of proteins in response to
pathogens into our blood to fight
with them. These proteins are
called antibodies. The
T-cells themselves do not secrete
antibodies but help B cells to
produce them.
describe the structure of antibodies
Each antibody
molecule has four peptide chains,
two small called light chains and
two longer called heavy chains.
Hence, an antibody is represented
as H2L2 .
These two
heavy chains are held together by disulphide bonds in shape Y,
Different types of antibodies are produced in our body. IgA, IgM,
IgE, IgG are some of them.
what are the 2 types of immune responses
Based on these two types of lymphocytes there are 2 types of active immune
system-
1. CMIS (Cell mediated immune system) or Cellular Immunity (T-cells)- This immune system is based on T- cells (60-70 %).
* When pathogen first enter inside the body first macrophage interact with
them & activates TH cells by releasing cytokines or interleukins (ILs) or
monokines.
- AMIS (Antibody mediated immune system) or Humoral Immunity (B-cells)
Based on B-lymphocytes (10-20 %) and these B-lymphocytes secrete the
antibodies.
Why is it that the organs cannot be taken from just anybody? What is it
that the doctors check?
- Grafts from just any source – an animal, another primate, or any human
beings cannot be made since the grafts would be rejected sooner or
later. - Tissue matching, blood group matching are essential before undertaking any
graft / transplant and even after this the patient has to take immuno-
suppressants all his/her life. - The body is able to differentiate ‘self’ and ‘non self’ and the Cell-mediated
immune response is responsible for the Graft Rejection.
what is meant by active immunity
- When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host
body. This type of immunity is called active immunity.
-Active immunity is slow and takes time to give its full effective response.
-Injecting the microbes deliberately during immunisation or infectious organisms gaining access into body during natural infection induce active immunity.
what is meant by passive immunity
When ready-made antibodies are directly given to protect the body against foreign agents, it is called passive immunity.
The yellowish fluid colostrum secreted by mother during the initial days of lactation has abundant antibodies (IgA) to protect the
infant.
The foetus also receives some antibodies from their mother, through the placenta during pregnancy. These are some examples of
passive immunity.
principle of vaccination
The principle of immunisation or vaccination is based on the property of ‘memory’ of the immune system.
In vaccination, a preparation of antigenic
proteins of pathogen or inactivated/weakened pathogen (vaccine) are introduced into the body.
The antibodies produced in the body against
these antigens would neutralise the pathogenic agents during actual infection.
The vaccines also generate memory – B and T-cells that recognise the pathogen quickly on subsequent exposure and overwhelm the
invaders with a massive production of antibodies.
principle of passive immunisation
. If a person is infected
with some deadly microbes to which quick immune response is required
as in tetanus, we need to directly inject the preformed antibodies, or
antitoxin (a preparation containing antibodies to the toxin). Even in cases
of snakebites, the injection which is given to the patients, contain preformed
antibodies against the snake venom. This type of immunisation is called
passive immunisation.
rdna tech for vaccines
Recombinant DNA technology has allowed the production of antigenic
polypeptides of pathogen in bacteria or yeast. Vaccines produced using
this approach allow large scale production and hence greater availability
for immunisation, e.g., hepatitis B vaccine produced from yeast.
what is an allergy? why is it causeD?
The exaggerated response of the immune system to certain antigens present in the environment is called allergy.
The substances to which such an immune response is produced are called allergens.
The antibodies produced to these are of IgE type.
Common examples of allergens are
mites in dust, pollens, animal dander, etc.
Symptoms of allergic reactions
include sneezing, watery eyes, running nose and difficulty in breathing.
Allergy is due to the release of chemicals like histamine and serotonin
from the mast cells.
how is the cause of an allergy determined
For determining the cause of allergy, the patient is exposed to or injected with very small doses of possible allergens, and the
reactions studied.
The use of drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy.
Somehow, modern-day
life style has resulted in lowering of immunity and more sensitivity to
allergens – more and more children in metro cities of India suffer from
allergies and asthma due to sensitivity to the environment. This could be
because of the protected environment provided early in life.
