Defence mechanisms of the host, Biology

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.

Posted Date: 9/17/2012 5:31:24 AM | Location : United States







Related Discussions:- Defence mechanisms of the host, Assignment Help, Ask Question on Defence mechanisms of the host, Get Answer, Expert's Help, Defence mechanisms of the host Discussions

Write discussion on Defence mechanisms of the host
Your posts are moderated
Related Questions
Q. Show the Artificial Keys? These are based on the resemblances and differences of some prominent characters in the taxa. These are based on the phylogenetic relationship b

Q. What is proteinuria? Why is proteinuria a sign of glomerular renal injury? Proteinuria means losing of proteins through urine under normal conditions proteins are too big to

Kyasanur forest disease Kyasanur forest disease (KFD) was first recognized in 1957 as a new disease entity affecting man and monkeys in Karnataka, India. The disease is named

Elaborate the term - Gill slits. Lateral opening in the wall of pharynx which allows water to enter into mouth and exit through the pharynx. This is one of the ancestral charac

Q. What is bathing in Cerebro-Spinal Fluid? The CNS is bathing in Cerebro-Spinal Fluid (or CSF):  similar to plasma, less protein, rich in ascorbic acid, different in ions Na+

Trichomonas vaginalis - Protozoan This cosmopolitan protozoan lives exclusively in the female vagina and male urethra or prostate. It causes a mild disease called trichomonas

What are all teh parts of a simple ciliated columnar epithilial cell?

Discuss the biological importance of Imidazole. Bring in examples of biomolecules that contain this group. Please be as thorough as possible.

If dimples may be considered a single-gene dominant trait, and 64% of the population features dimples, calculate the frequencies of heterozygotes and both types of homozygotes, ass

W A TER Occurence Water is the most abundant substance, covering 70% of earth's surface. It constitutes 60-90% of living cells.              5-6% in tooth e