Defence mechanisms of the host, Biology

Assignment Help:

Defence mechanisms of the host


The healthy animal is protected from pathogenic organisms present in the environment by virtue of the effective immune mechanism present from birth. This innate resistance is non-specific in nature i.e. it is effective against most of the pathogens. The intact skin and mucous membranes of the body afford effective protection against pathogenic organism. Acidic pH of the gastro intestinal tract, lacrimation, ciliated mucous membrane of the nasal passage and sphincters of the natural orifices are some of the natural defence mechanisms. The reticuloendothelial system (RES) of an animal body provides an effective defence mechanism by engulfing and destroying the foreign particles like bacteria. Macrophages of Metchnikoff constitute the main cellular scavenging network of the body. Besides this, genetically a particular species could be resistant to a specific pathogen. This mechanism depends on many factors such as the absence of specific microbes binding receptors, body temperature and the animal habitat. Other type of resistance is acquired resistance which is acquired when an animal comes in contact with a particular organisms. It is of two types, viz. humoral immunity and cell-mediated immunity. The first one largely depends on the presence of antibodies in the tissue fluids and the later type is attributed largely by the phagocytic cells The acquired immunity also develops with the introduction of vaccines or toxoids in animal body.


Carriers:
Occasionally, a situation arises after recovery from a disease or because of the partial resistance of the host or the inability of the causal agent to produce the  disease syndrome in the host, the organism lives in the host without showing any symptoms of the disease, and the host itself is unable to completely get rid of the organism and cause disease in susceptible animals. The bacteria sometimes actively multiply and bring about a fresh outbreak of the disease as a result of breakdown in the balance between the host and the parasite under certain stress factors. The carriers could be classified as contact carriers, convalescent carriers and immune carriers.


Related Discussions:- Defence mechanisms of the host

Vitamins, Which vitamin is useful for the clotting of blood?

Which vitamin is useful for the clotting of blood?

Oxygen cycle, Oxygen is a major component of all living organisms. All the ...

Oxygen is a major component of all living organisms. All the organisms and plants required oxygen for aerobic respiration which they absorb from environment. Only plants release ox

Why is it significant that exact copies of dna, Why is it significant that ...

Why is it significant that exact copies of DNA are produced during replication? Producing exact copies make sure that when a cell divides, the offspring cells will receive the

Discuss the presence and occurrence of lactase persistence, Lactase non-per...

Lactase non-persistence is an example of a genetic trait that has been influenced by cultural factors.Domestication of animals by humans began approximately 10  000 years ago. Farm

Objective of ecological study, The main objectives of study of ecology are:...

The main objectives of study of ecology are: (i)              To study the distribution of biota local and geographical level. (ii)             To study the interrelationship

Describe the monomer unit of a protein, Describe the monomer unit of a prot...

Describe the monomer unit of a protein and how monomer units are assembled into peptides.

What are the illustrations of the criminal law, What are the illustrations ...

What are the illustrations of the criminal law? Illustrations of crimes' law: Illustrations of crimes are theft, reckless or murder behaviour. The major aim of illegal

How does the structure of a crab relate to its habitat, How does the struct...

How does the structure of a crab relate to its habitat? It's difficult exoskeleton protects it for most predators & keeps water off its flesh. The claws are used for mating due

Explain the lateral and the apical buds of the plants, What is the differen...

What is the difference between the lateral and the apical buds of the plants? Lateral buds are portions of meristematic tissue situated in the base of the shoots. Apical bud

Chloroplasts, CHLOROPLASTS Schimper (1883) coined the term chlorop...

CHLOROPLASTS Schimper (1883) coined the term chloroplastid for green plastids. Mayer called them Autoplast. Chloroplast name proposed by Erera. Green plastids wi

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd