Test: Human Health & Disease - NEET MCQ

A healthy person acquires the infection by inhaling the droplets/aerosols released by an infected person or even by sharing glasses and utensils with an infected person.

Paroxyms a sudden attack or outburst of a particular emotion or activity. Quotidian malaria in which the febrile paroxysms occur daily. In P. malariae infection, the relapses occur once every 72 hours and it is called Quartan malaria.

Male Anopheles mosquito do not have piercing and sucking type of mouth parts. So, they can not inject malarial parasite into man.

Malaria is caused by Plasmodium whose sexual phase occurs in the mosquito Anopheles. When female Anopheles feed on blood, they can serve as vector host for malarial parasite.

Diarrhoeal disease conditions include frequent and excessive discharge of watery material from the bowel. Such diseases mostly result from ingestion of harmful germs with food and water. E. coli, Shigella sp. & salmonella sp. causes diarrhoea. Diarrhoea caused by virus, bacteria or parasites possesses two characteristics- firstly, the offending organisms colonise the intestine and as a consequence cause inflammation of the intestine or enteritis; and secondly, they upset the balance of intestinal fluid absorption and secretion mechanism, often enhancing the latter very considerably, which is then manifested as watery stool discharged frequently in large volumes. Shigella sp, Salmonella sp. are quite closely related genera that are responsible for diarrhoeal diseases. Dehydration is common to all types of diarrhoeal diseases & adequate supply of fluids & electrolytes that provides ions, should be ensured.

Rabies (hydrophobia) is caused by rabies virus. Its vectors are raboid animals especially dogs. It leads to encephalitis, fear of water (hydrophobia), high fever, severe headache, spasm of throat & chest, leading to death.

Human infection is direct and oral. It occurs by eating raw or under-cooked measly pork (Pig muscle with cysticerus larvae of Taenia). Infection in vegetarians occurs through improperly washed vegetable. So proper cooking of pork and properly washed vegetable to avoid Taenia infection.

Endoparasite lives inside its host. Bovine endoparasites may be divided into three categories: nematodes, or roundworms; cestodes, or tapeworms; and trematodes, or flukes.

If a giardia infection is present, the parasite or its cysts can be seen when the stoolis looked at under a microscope. If giardiasis is suspected, an antigen test may be done on the stool or a sample of the fluid from the small intestine (duodenal contents). Giardia is a genus of anaerobic flagellated protozoan parasites of the phylum Sarcomastigophora that colonise and reproduce in the small intestines of several vertebrates, causing giardiasis.

On November 16, 2002, an outbreak of what is believed to be severe acute respiratory syndrome (SARS), began in the Guangdong province of China, which borders on Hong Kong. China is the most populated country in the World.

B-cells work chiefly by secreting soluble substances called antibodies into the body's fluids or humors. Antigens are proteins that are found on the surface of the pathogen. Antigens are unique to that pathogen. When an antigen enters the body, the immune system produces antibodies against it.

Virus infected cells secrete proteins called interferons, which protect non-infected cells from further viral infection.

Immunoglobulins, also known as antibodies, are glycoprotein molecules produced by plasma cells (white blood cells). The Ig monomer is a "Y"-shaped molecule that consists of four polypeptide chains; two identical heavy chains and two identical light chains connected by disulfide bonds.

Innate immunity refers to nonspecific defense mechanisms that come into play immediately or within hours of an antigen's appearance in the body. Four barriers are physical, physiological, cellular and cytokine barriers.

Cell-mediated immunity (CMI) is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, antigen-specific cytotoxic Tlymphocytes, and the release of various cytokines in response to an antigen. The immune response to a transplanted organ consists of both cellular(lymphocyte mediated) and humoral (antibody mediated) mechanisms. Although other cell types are also involved, the T cells are central in the rejection of grafts.

Humans are exposed to large number of infectious agents, However, only a few of these exposures result in disease due to the fact that the body is able to defend itself from most of these foreign agents. This overall ability of the host to fight the disease-causing organisms conferred by the immune system is called immunity

Acquired immunity is pathogen specific, it is characterised by memory. When our body encounters a pathogen for the first time it produces a response called primary response which is of low intensity. Subsequent encounter with the same pathogen elicits a highly intensified secondary or anamnestic response. This is ascribed to the fact that our body appears to have memory of the first encounter.

Innate immunity is non-specific type of defence, that is present at the time of birth. This is accomplished by providing different types of barriers to the entry of the foreign agents into our body. Skin on our body is the main barrier which prevents entry of the micro-organisms. Mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts also help in trapping microbes from entering our body.

Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection. Interferons are a group of related low molecular weight regulatory cytokines produced by certain eukaryotic cells in response to a viral infection. Besides defending against viruses, they also help to regulate the immune response.

Some transplanted tissues do not stimulate an immune response. For example a transplanted cornea is rarely rejected because lymphocytes do not circulate into the anterior chamber of the eye. Thus, this site is considered as immunologically privileged site.