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. What is tubal pregnancy? Many times fecundation takes place in the Fallopian tubes in general the newly formed zygote is taken to the uterus where nidation and the embryonic

Equine influenza Equine influenza is a highly contagious, epizootic disease, which affects equines of all age groups and is caused by influenza virus A/equine virus of family

State in brief about the soil horizon A  soil horizon may be defined as "a horizontal layer of regolith, approximately parallel to the soil surface, and possessing relatively

Determine the significance of Mesoglea. The jellylike layer found between endodermal and ectodermal cell layers of diploblastic organisms. It acts as a type of cement holding t

What is the Echocardiogram ? When doubts persist whether a patient has CHD or not despite a thorough clinical exam and chest X-ray, ECG, and hyperoxia test, an echocardiogram s

Advances in neurodiagnostic techniques Major scientific and technology advances have made it easier to correlate behaviours suspected as having a neurological basis with actual

Q. Reasons for increasing popularity of dental implants? There are various reasons for increased popularity of dental implants. With the rapid development and evolution of impl

Failure to organize proper adjusting entries causes net income and the balance sheet to be in error. Using Micro Train Company as an instance this section has discussed and illustr

Long-term Follow-up Results :  To evaluate the long-term results of surgery, one has to take into consideration the natural history, results of medical treatment and that of PTCA.

Define Water as a medium and solvent? Water is the medium of all cell fluids, including digestive juices, lymph, blood, urine, and perspiration. All the physiochemical reaction