Shailesh Koirala 
The lungs remain protected from various inhaled particles, microorganisms and toxic gases by the respiratory defense mechanism. There are various ways by which this mechanism works such as filtration of the air, the muco-ciliary clearance system, the cough reflex, reflex broncho-constriction and alveolar macrophages. A) Filtration of air Presence of nasal hairs keeps the inspired … Read more
An infectious disease which is caused by Mycobacterium tuberculosis is called tuberculosis. It is a primary cause of death worldwide that is a potentially curable infectious disease. Death of HIV patients is mostly due to the secondary infection i.e. tuberculosis. The incidence of TB worldwide was decreased until the mid-1980s when HIV disease emerged. There … Read more
Fluid spacing is a term that describes the distribution of water present in a body. There are different types of fluid spacing where first spacing means the normal distribution of fluid in ICF (Intra-cellular Fluid) and ECF (Extra-cellular Fluid) compartments. Second spacing means an abnormal accumulation of interstitial fluid in body (i.e., edema). Third spacing … Read more
The domestic sewage or liquid industrial waste that cannot be discarded in untreated form into water sources like lakes or streams due to public health, economic, environmental and aesthetic considerations is called wastewater. The treatment of wastewater relies on industrial scale use of microorganisms for bio-conversion. Wastewater enters a treatment plant and following the treatment, … Read more
Beers and ales are alcoholic beverages that are popular and produced worldwide by the fermentation of grains and other sources of starch. Grape and other fruit juices are not used for these products as they are fermented for the production of wine. Although both the brewing and wine industries uses yeast to catalyze the fermentation … Read more
Chemical and physical state of the environment greatly affects the activities of the microorganisms. Many environmental factors can be considered among which four key factors control the growth of all microorganisms: temperature, pH, water availability and oxygen. Some other factors can also potentially affect the growth of microorganisms like pressure and radiation. Temperature It is … Read more
The oral cavity is one of a complex, heterogeneous microbial habitat. Saliva contains microbial nutrients, but it is not an especially good growth medium because the nutrients are present in low concentration. Also the saliva contains antimicrobial substances. Saliva contains an enzyme lysozyme that cleaves glycosidic linkages in peptidoglycan present in the bacterial cell wall, … Read more
These bacteria carry out an-oxygenic photosynthesis. Thus, unlike the cyanobacteria oxygen is not released by these groups. These bacteria are a morphologically diverse group and their classification has been established along phylogenetic, morphological and physiological lines. Different genera fall within the Alpha-, Beta-, or Gammaproteobacteria. Bacteriochlorophylls and carotenoid pigments are present on them. Due to … Read more
Many microorganisms including prokaryotes and eukaryotes respond to adverse conditions by forming spores. When the good condition returns once, the spore germinates and the microorganism returns to its normal life cycle. Among the bacterial group, the genus Bacillus is well known for the formation of endospores which means the spores formed inside the mother … Read more
It is a special type of diffusion, which involves the movement of water through a semi-permeable membrane (differentially permeable membrane). The movement of molecules takes place from the region of higher concentration of water (dilute solution) to the region of lower concentration of water (stronger solution) until the equilibrium. It can also be defined as … Read more