Assessment Questions on IMMUNOLOGY-AN OVERVIEW

                                         IMMUNOLOGY-AN OVERVIEW

1. Injection of anti-venom to a patient for snake bite is an example of

a Naturally acquired active immunity
b Artificially acquired active immunity
c Naturally acquired passive immunity
d Artificially acquired passive immunity

2. Newborns get their antibodies from mothers’ milk. This is an example of

a Naturally acquired passive immunity
b Artificially acquired passive immunity
c Naturally acquired active immunity
d Artificially acquired active immunity

3 Vaccination is an example of

a Naturally acquired active immunity
b Artificially acquired active immunity
c Naturally acquired passive immunity
d Artificially acquired passive immunity

4 Often patients are immune to diseases like chicken pox once infected. This immunity is an example of 

a Naturally acquired active immunity
b Artificially acquired active immunity
c Naturally acquired passive immunity
d Artificially acquired passive immunity

5 Skin is the largest organ in the body and protects us by preventing pathogen entry. This is an example of 

a Naturally acquired innate immunity
b Artificially acquired adaptive immunity
c Naturally acquired passive immunity
d Artificially acquired passive immunity

IMMUNOLOGY-AN OVERVIEW

 

IMMUNOLOGY-AN OVERVIEW

1 MARK QUESTIONS

1.      Immunity

The power of a versatile defence system that has evolved to protect animals from invading pathogenic microorganisms and cancer is called immunity. It is able to generate an enormous variety of cells and molecules capable of specifically recognizing and eliminating an apparently limitless variety of foreign invaders like pathogens or antigens

2.      Innate immunity

Innate immunity is the less specific component that provides the rapid, first line of defence against infection. Most components of innate immunity are present before the onset of infection. Phagocytic cells, such as macrophages and neutrophils, barriers such as skin, and a variety of antimicrobial compounds synthesized by the host all play important roles in innate immunity by recognizing and clearing frequently encountered pathogens.

3.      Acquired/adaptive immunity

Adaptive immunity is the quicker, stronger and specific immunity against an antigen within five or six days after the initial exposure to that antigen. Exposure to the same antigen sometimes in the future results in a memory response. It is more effective in neutralizing and clearing the pathogen by utilizing antibodies or cell mediated mechanisms.The major agents of adaptive immunity are lymphocytes and the antibodies and other molecules they produce.

4.      Components of innate immunity

Phagocytic cells (macrophages, neutrophils, monocytes), NK cells, barriers (skin), Microbial probionts, Surface secretions (acids, sweat, sebum, mucus, proteolytic enzymes, lactoperoxidase in milk), Mechanical action (Peristalsis, Washing effect of tears, saliva and urine) etc.

5.      Phagocytes

Phagocytes are some specialized cells, such as blood monocytes, neutrophils, and tissue macrophages which uptake materials from its environment. In phagocytosis, a cell’s plasma membrane expands around the particulate material, (an antigen or whole pathogenic microorganisms) to form large vesicles called phagosomes which are later lysed by proteolytic secretions of the lysosomes in the cell.

 6.      NK cells

These are large granular lymphocytes and one of the null cells thatlack surface antigens
(T-cell receptors or immunoglobulin incorporated in their plasma membranes). These cells display cytotoxic activity against a wide range of tumour cells in the absence of any previous immunization with the tumour. They distinguish infected cells and tumours from normal and uninfected cells and induce infected cells to undergo apoptosis (cell death) by releasing cytotoxic granules.

7.      Inflammation

Tissue damage caused by a wound or by an invading pathogenic microorganism induces a complex sequence of events collectively known as the inflammatory response for the clearance of the invader. The sequence of events include vasodilation and increased blood supply to the site of infection, increase in capillary permeability and an influx of lymphocytes and serum proteins from the engorged capillaries into the tissue, and the phagocytosis of antigens. Four cardinal signs of inflammation are rubor (redness), tumor (swelling), calor (heat), and dolor (pain).

8.      Pus

During inflammation, as phagocytic cells (neutrophils and monocytes) accumulate at the site of infection and begin to phagocytose antigens or pathogens, phagocytes release lytic enzymes which can damage nearby healthy cells. The accumulation of dead cells, digested material, and fluid forms a substance called pus.

9.      Active immunity

Active immunity is the form of immunity that is induced in an individual by exposure to a foreign antigen either naturally or artificially. It is so called because the immunized individual plays an active role in responding to the antigen by eliciting his acquired immunity (proliferation of antigen-reactive T and B cells resulting in the formation of memory cells).

e.g., Normal immune response to an infection (natural) and immunity attained by vaccination (artificial)

10.  Passive immunity

The immunity against a particular antigen/pathogen conferred on an individual by transferring serum or lymphocytes from an immunized individual is called passive immunity. It is so called because the individual does not play active role in attaining immunity but he receives preformed antibody from another organism.

e.g., Immunity attained by maternal antibodies obtained through breast milk (natural) and immunity obtained by antivenom against snake bite (artificial).

11.  Vaccines

Vaccines are either killed or live attenuated pathogens or toxoids (inactive toxins). These are administered to individual either orally or through injections. These vaccines cannot actively infect cells or produce any harmful products but are soon neutralized by the acquired immunity of the individual because vaccines are killed or weakened pathogens or inactive toxins. During this immune response the individual develops memory cells which will later identify the same pathogen up on further exposure and neutralize it in a very short period of time.e.g., vaccines against typhoid, cholera, pertussis, plague, rabies, polio etc.

12.  Humoral immunity

Immunity provided by specific chemical substances called antibodies that are synthesised by plasma cells derived from B lymphocytes is called humoralimmunity. It is so called because the antibodies secreted circulate in the body fluids (humor) such as blood plasma and lymph.

13.  Cell-mediated immunity

Immunity provided by T cells and their secretions like cytokines and lymphotoxins is called cell-mediated immunity. Upon antigenic stimulation, effector T cells are generated. Both activated T_H cells and cytotoxic T lymphocytes (CTLs) serve as effector cells in cell-mediated immune reactions. T_H cells secretecytokines which can activate various phagocytic cells, enabling them to phagocytose and kill microorganisms more effectively. Cytokines also activate T_C cells to CTLs which kill altered self-cells (infected cells), virus infected cells and tumour cells.

 

   

2/4 MARK QUESTIONS

1.      Explain various levels of innate immunity

i. Species level-Immunity shown to a pathogen by all members of a species.
eg.,            1. Salmonella, Vibrio choleraeand Treponema pallidum are humanpathogens. But we are resistant to Rinderpest, which is pathogenic to cattles.

ii. Racial level-Immunity shared by most of the members of a genetically related population.
eg., 1. Algerian race sheep is resistant to anthrax. 2. Negroes in Central Africa resistant to falciparum malaria

iii. Individuallevel- Immunity shown to a pathogen by an individual within a given race and not shared by most other members of the race or species.

eg.,      1. Homozygous twins show similar degree of resistance to leprosy or tuberculosis

1.      Briefly explain inflammation

Tissue damage caused by a wound or by an invading pathogenic microorganism induces a complex sequence of events collectively known as the inflammatory response for the clearance of the invader. The sequence of events include vasodilation and increased blood supply to the site of infection, increase in capillary permeability and an influx of lymphocytes and serum proteins from the engorged capillaries into the tissue and phagocytosis of antigens.

Vasodilation and an increase in capillary permeability facilitates an influx of fluid and cells from the engorged capillaries into the tissue. An increase in the diameter of blood vessels and accumulation of exudate contribute to tissue redness (erythema) and tissue swelling (edema) and thereby an increase in tissue temperature. As phagocytes influx(chemotaxis)from the capillaries into the tissues at the site of infection and begin to phagocytose pathogens, they release lytic enzymes,which can damage nearby healthy cells.The accumulation of dead cells,digested material,and fluid forms a substance called pus.

2.      Describe briefly Four characteristic attributes of adaptive immunity

Adaptive immunity displays four characteristic attributes: 

1) Antigenic specificity, 2) Diversity, 3) Immunologic memory and 4) Self/nonself recognition.

The antigenic specificityof the immune system permits it to distinguish subtle differences among antigens. Antibodies can distinguish between two protein molecules that differ in only a single amino acid. The immune system is capable of generating tremendous diversityin its recognition molecules, allowing it to recognize billions of unique structures on foreign antigens. Once the immune system has recognized and responded to an antigen, it exhibits immunologic memory; that is, a second encounter with the same antigen induces a heightened state of immune reactivity. Because of this attribute,the immune system can confer life-long immunity to many infectious agents after an initial encounter.Finally,the immune system normally responds only to foreign antigens, indicating that it is capable of self/non-self recognition. The ability of the immune system to distinguish self from non-self and respond only to non-self molecules is essential, for the outcome of an inappropriate response to self-molecules can be fatal.

3.      Distinguish between innate immunity and adaptive immunity.

Innate immunity is the less specific component that provides the rapid, first line of defence against infection by the components which are present in the body before the onset of infection. Phagocytic cells, such as macrophages and neutrophils, barriers such as skin, and a variety of antimicrobial compounds synthesized by the host all play important roles in innate immunity by recognizing and clearing frequently encountered pathogens.

Adaptive immunity is the quicker, stronger and specific immunity against an antigen within five or six days after the initial exposure to that antigen.Exposure to an antigen will induce T cells to synthesize and secrete cytokines which in turn activates B cells to secrete antibodies (humoral immunity) and Tc cells to secrete lymphotoxins (cell mediated immunity). Antibodies bind neutralize antigens and lymphotoxins destroys the infected cells. Exposure to the same antigen sometimes in the future results in a memory response by retaining activated B cells (Memory cells) during prior infection. Memory cells can identify the antigen at once during later infections and bring about humoral immunity immediately after the infection. Because of this attribute,the immune system can confer life-long immunity to many infectious agents after an initial encounter.

Protect the vanishing vultures, the scavengers..

http://www.facebook.com/jasinrahman

Hornbills too on the verge of extinction

Hornbills are important flagships of the tropical Asian forests and their ecological importance as seed dispersers is well known. These magnificent birds with specialised nesting and feeding habits are threatened due to habitat loss, fragmentation, and hunting.



The Western Ghats biodiversity hotspot in India is threatened by habitat loss and fragmentation due to deforestation for timber, plantation and buildings

Hornbills are a group of peculiar, large-bodied birds found only in the 'Old World tropics' that have been the focus of much conservation attention. Of the 54 species of hornbills known from the world nine occur within India and four occur in the Western Ghats:Malabar Pied Hornbill Anthracoceros coronatus and Indian Grey Hornbill Ocyceros birostris (endemic to Indian subcontinent), Malabar Grey Hornbill Ocyceros griseus

(endemic to Western Ghats), and the Great Hornbill Buceros bicornis.
(Indebted to M. Divya and S. Raman, NCF)

Will continue.....

Is cheetah programme of Govt. of India sound?

Do we want the cheetah back? 
A recent assessment conducted by the MoEF, the Wildlife Institute of India and the Wildlife Trust of India has identified the Kuno-Palpur and Nauradehi Wildlife Sanctuaries in Madhya Pradesh and the Shahgarh Landscape in Jaisalmer for the introduction of cheetah.
An estimated 300 crore will be spent initially on the project and potential sources for the animals are also being explored. It s quite likely that the cheetahs, if they come, will be either from Namibia or South Africa. 




Why is Cheetah to be back?

As per ministry it is to regain a part of the lost glory and
history of this country. The magnificent cheetah that was once a living, bounding part of this nation's reality must be brought back. The other, as has been pointed by some wildlife experts, is that the cheetah, like the tiger, is the apex species of the grassland habitat and it s presence would, both, indicate and ensure the health of this badly abused ecosystem.
M K Ranjitsinh, doyen of Indian wildlife conservation and a prime mover of the cheetah reintroduction project has argued that, The cheetah restoration will be part of a prototype for restoration of original cheetah habitats and their biodiversity, helping to stem the degradation and rapid loss of biodiversity. He also noted that re-introducing the cheetah will help to save other threatened grassland-scrub-open woodland species such as the caracal, Indian wolf, the desert cat, the Great Indian Bustard and the Lesser Florican.  Prima facie the arguments seem valid, but if looked at carefully, both have
serious problems.

What is the reality?

It seems that introducing the Chettah from Africa is meaning less and sheer waste of time and money. The African species is different from the Asian Chettah which became extinct in
1948. 
And therefore this will be a foreign element in our ecosystem.
It is like introducing Eucalyptus tree from Australia in our country.
It is a bad project.
To protect grasslands, we don't need Chettah.
These projects are just to displace more people from their homelands and nothing else. 
Why spend so much money on introducing a foreign animal in our ecosystem? 
What has the forest department done to our grasslands? 
Just see Ranebennur Black Buck Sanctuary in Karnataka which has some of the remaining Great Indian Bustard left. 

This bird is like a aeroplane, it needs to run to take off. Introducing Eucalyptus on these grasslands has resulted in these birds not able to run to take off. They often hit the trees and die or fall prey to wolves. Now Chettah also needs huge grasslands to run, we dont have such big grasslands like the African Savannah forests. 
The Indian Chettah lived in the scrubs and grasslands and was
more adapted to this region. This African Chettah will not be able to do so,eventually it will die, but in the process the government will successfully relocate poor people from their homelands and grab those lands in this era of Climate change. 
Introducing Lion from Gir to other forests in India however is not a bad idea. Since we had Lions all over the country once upon a time. And in Gir we have hardly 200-300 Lions which are the last of Asian Lions. THis can adapt since it belongs to our region. That could be tried in other forest regions in the country. Not this Cheetah. 

It amazed me with its charming chime!!!!

Malabar Whistling Thrush 

The Malabar Whistling  Thrush   (Myophonus horsfieldii) is a Whistling Thrush in the thrush family Turdidae. They are also known locally by the name of 'Whistling Schoolboy' for the whistling  calls that they make at dawn with a very human quality. The species is a resident in the Western Ghats and associated hills of peninsular India including central India and parts of the Eastern Ghats. This is a bold species and is often found close to human habitation. 

The male sings its varied and melodious whistling song from trees during summer. They may sing for long early at dawn but at other times of the day they often utter sharp single or two note whistles. They were once popular as cage birds, because of their ability to learn entire tunes. They bathe frequently in water usually in the morning and evening but at mid day during hot weather.

People often mistake it as 'kuyil' (koel). Koel or Cuckoos are in the family of Cuculidae, but Malabar Whistling Thrush belongs to Turdidae. Also it shows parental care which is lacked by Cuckoos. To see the parental care of Malabar Whistling Thrush visit http://www.youtube.com/watch?v=GdVLnef6lHU&feature=fvw 

Importance of wild life conservation

What is meant by wild life and what is its importance?

Wild life refers to all living organisms in their natural habitat other than cultivated plants and domesticated animals.

Due to indiscriminate deforestation, nature lovers are becoming alert to protect the endangered species of wildlife as well as those that are on the verge of extinction and thus save the world from running out its green heritage and natural balance.

The wild life is important in view of following facts:

Wild life maintains ecological 'balance of nature' and continuity of food chain and nature cycles. It helps in maintaining the balanced living systems of earth, which consequently ensures survival of life.

Wild life has got economic value in terms of natural products like gum, honey, dead wood timber and medicinal plants.

Water bodies, the 'elixir of life' originate from forests and flow down hill to support the life of all living organisms.

Wild life offers large gene pool for the scientists to carry out breeding programmes in agriculture, animal husbandry and fishery.

It provides aesthetic value to man. By their unique way of existence, wild creatures exaggerate the natural beauty of the earth.

Wild life of a country is its heritage and cultural asset.