AnswEr KEY 1 (a) 2 (b) 3 (d) 4 (d) 5 (b)
SHORT ANSWER TYPE QUESTIONS
4. Write the four differences between blood plasma and serum.
7. ANSWERS
Part - I
1. (d) 2. (d) 3. (c) 4. (d) 5. (a) 6. (a) 7. (a) 8. (b) 9. (c) 10. (a) Part - II 1. (d) 2. (a) 3. (c) 4. (a) 5. (d) 6. (d) 7. (a) 8. (c) 9. (c) 10. (a) 11. (c) 12. (b) 13. (a) 14. (b) 15. (a) 16. (b) 17. (b) 18. (a) 19. (d) 20. (b) 21. (a) 22. (b) 23. (d) 24. (b) 25. (a) 26. (c) 27. (c) 28. (b) 29. (b) 30. (c) 31. (a) 32. (d) 33. (b) 34. (c) 35. (b) 36. (c) 37. (b) 38. (a) 39. (a) 40. (c) 41. (d) 42. (c) 43. (c) 44. (d) 45. (d) 46. (a) 47. (a) 48. (d) 49. (b) 50. (b) 51. (c) 52. (b) 53. (c) 54. (d) 55. (b) Part - III 1. (c) 2. (a) 3. (c) 4. (b) 5. (d) 6. (c) Part - IV
1. (i) conjugate, globin (ii) Erythropoietin (iii) Basophils (iv) megakaryocytes (v) Prothrombinase
2.
Erythrocytes Leucocytes
1. They are smaller, more numerous and longer lived cells than the leucocytes.
They are larger, fewer, shorter-lived cells than erythrocytes.
2. They have a fixed form. RBCs of man are circular, biconcave and enucleated.
They are rounded but can change their shape.
3. They occur only in blood vessels.
They can escape from capillaries into the tissues (diapedesis).
4. They lose cell organelles (ER, mitochondria, ribosomes, centrioles) during development.
They retain cell organelles (ER, mitochondria, ribosomes, centrioles).
5. They have haemoglobin. They lack haemoglobin. 3. Blood clotting or blood coagulation process can be
described under three major steps.
− First step : At the site of an injury, the blood platelets disintegrate and release a phospholipid, called platelet factor-3 (= Platelet thromboplastin). Injured tissues also release a lipoprotein factor called thromboplastin. These two factors combine with calcium ions (Ca++)
and certain protein of the blood plasma to form an enzyme called prothrombinase.
Second step :
− Prothrombinase catalyzes breakdown of prothrombin (inactive plasma protein) into an active protein called thrombin and some small peptide fragments.
− Third step : Thrombin acts as enzyme and first brings about depolymerization of fibrinogen (a soluble plasma protein) into its monomers. Later thrombin stimulates repolymerization of these monomers into long insoluble fibre-like polymers called fibrin. The thin, long and solid fibres of fibrin form a dense network upon the wound and trap blood corpuscles (RBCs, WBCs and platelets) to form a clot. The clot seals the wound and stops bleeding.
4.
Blood plasma Blood serum
1. It is the fluid minus blood
corpuscles. It is liquid minus clotting elements. 2. It is faint yellow in colour. It is pale yellow.
3. It has fibrinogen and other clotting materials.
It does not have fibrinogen and other clotting materials. 4. It takes part in blood
clotting.
It does not take part in blood clotting.
nn
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February ’13 49 Analysis of various PMTs from 2007-20122012
AIIMS BHU AFMC AMU
2011
AIPMT AIIMS BHU AFMC
2010
AIIMS BHU AFMC AMU AIPMT
2009
AIIMS BHU AFMC AMU AIPMT
2008
AIPMT AIIMS BHU AFMC AMU AMU 2007 1 2 5 3 4 6
AIPMT AIIMS BHU AFMC
AMU AIPMT 1 2 5 3 4 6 1 2 5 3 4 6 1 2 5 3 4 6 1 2 5 3 4 6 1 2 5 3 4 6 BAcTerIAL DIseAses
bacteria are microscopic single-celled organisms at least
•
1 micron long.
body tissues and systems can be damaged by pathogenic
•
bacteria in two ways - true infections and effects of toxins.
Types of bacterial diseases are typhoid, pneumonia,
•
dysentery, plague, diphtheria, anthrax, tuberculosis, whooping cough, cholera, leprosy and tetanus.
Typhoid (Enteric fever)
Typhoid is a common bacterial disease caused by a rod-like
•
bacterium, Salmonella typhi, which is commonly found in the intestine of man.
Incubation period varies from 1-3 weeks,
• average 2
weeks.
Typhoid spreads through
• food and water contaminated
with faeces of the patient. House flies may carry the pathogens from the faeces to the food, milk and water.
Th
• is disease is characterised by the inflammation of ileum and colon, liver and spleen also become enlarged, abdominal pain, pea soup diarrhoea which may become haemorrhagic, constant fever, extreme weakness, vomiting, rash of rose coloured sporst called rose spots on the upper abdomen and sore throat.
It is diagnosed by
• Widal Test.
Certain humans function as carriers without suffering from it.
•
Mary Mallon nicknamed
• Typhoid Mary was a cook by
profession and was a typhoid carrier who continued to spread typhoid for several years through the food she prepared.
TAB vaccine
• provide immunity for about 3 years.
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February ’13losses are replaced, recovery occurs within 7-10 days; antibiotics may be given to eliminate the bacteria. Plague (Black death)
Plague is caused by a rod shaped non-motile bacterium
•
called Pasteurella/Yersinia pestis and is transmitted by the bite of infected rat flea, Xenopsylla cheopis.
Pasteurella pestis
• is endoparasite of gut of rat flea (which is an ectoparasite of rat and mouse).
Head louse
• (Pediculus) and bedbug (Cimex) may also transmit the germ from man to man.
It is of 3 types–
• bubonic plague, septicemic plague and
pneumonic plague.
Bubonic plague
• (black death) has an incubation period of 2 - 6 days. Pathogen multiplies in lymph nodes, especially armpit and groin which swell up into painful buboes. Other
• symptoms are high fever, chill, delirium, exhaustion and haemorrhages which turn black. The patient dies thereafter. Hence, plague is also called black death. Plague reached In
• dia for the first time in 1895
from Hong Kong. In
• septicemic plague buboes do not occur. It is characterised by sepsis, severe headchae, rapid pulse, fever, chill, nausea, vomiting and delirium leading to death within two days.
Pneumatic or pneumonic plague
• infects lungs causing
pulmonary oedema, fever, anoxia, delirium and death within 24 hours.
anti-plague vaccine, spray of insecticides, killing of rats,
•
and high cots (rat flea can jump upto 45 cm) are some preventive measures.
Plague is confirmed by
• Wayson stain test.
Diphtheria
Diphtheria is an acute infectious disease of mostly children
•
characterized by the development of a grey adherent false membrane over the upper respiratory tract
or throat.
It is caused by toxigenic
•
strains of Corynebacterium diphtheriae (Gram +ve
bacterium). Incubation period is • of 2-5 days. Endotoxin • pro- duced by pathogen causes nasal diphtheria, pharyngeal diphtheria and laryngotracheal diphtheria. Symptoms
• are fever, sore Pneumonia
Pneumonia is c
• aused by Streptococcus pneumoniae or Diplococcus pneumoniae, and Haemophilus influenzae, having an incubation period of 1-3 days.
It is a serious disease of lungs characterised by
• accumulation
of mucus/fluid in alveoli and bronchioles to that extent that breathing becomes difficult.
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. Pneumonia is of two types :
•
Lobar pneumonia
– affects whole lobes and is usually caused by Streptococcus pneumoniae.
Lobular pneumonia
– refers to multiple patchy
shadows in a localized or segmental area. When these multiple shadows are widespread, the term
bronchopneumonia is used. In this the infection starts in bronchi and spreads in a patchy manner into the alveoli.
The onset of pneumonia is usually sudden with a single
•
shaking chill, followed by fever, pain with breathing on the side of lung involved, increased pulse and respiratory rates and cough.
In severe cases the lips and fing
• er nails turn grey to bluish
in colour. Dysentery
Dysentery is an infection
• of the intestinal tract causing
severe diarrhoea with blood and mucus.
amoebic dysentery (amoebiasis) is caused by the protozoan
•
Entamoeba histolytica.
Bacillary dysentery
• is caused by bacteria such as
Shigella dysenteriae, Escherichia coli, Campylobacter and Salmonella and is spread by contact with a patient or carrier or through food or water contaminated by their faeces.
epidemics are common in overcrowded
•
insanitary conditions. Symptoms,
• which develop
1-6 days after infection, include diarrhoea, nausea, cramp, and fever and they persist for about a week.
an attack may vary from
•
mild diarrhoea to an acute infection causing serious dehydration and bleeding from the gut.
In most cases, provided fluid
•
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February ’13 51throat, sometimes vomiting, headache, epithelial necrosis by endotoxin and oozing of semisolid material in the throat
which develops into a grey false but tough membrane. The membrane chokes the air passage. Sometimes,
•
bacterium infects the heart leading to fatal heart blockage.
In severe cases, respiratory tract is blocked causing difficulty
•
in breathing and even death due to choking.
The germs are present in the discharges from the nose and
•
throat of patients and also of healthy people who act as the “carriers”.
The patients and the carriers spread the disease through
•
acts like kissing, talking, coughing and sneezing. DPT vaccine -
• diphtheria, pertussis and tetanus vaccine is given as immunization within six weeks of birth.
‘Schick test’
• tests the presence of antitoxin and the state of hypersensitivity to diphtheria toxin.
Anthrax (Biowar disease) anthrax is an
• acute infectious disease caused by air-borne, spore-forming, rod-like, nonmotile bacterium, Bacillus anthracis.
It most commonly occurs in wild and domestic lower
•
vertebrates (cattle, sheep, goats, camels, antelopes, and other herbivores), but it can also occur in humans when they are exposed to infected animals or tissues from infected animals.
Infected animals shed in the discharges from the mouth,
•
nose and rectum a large number of bacilli (bacteria) which sporulate in the soil. These spores are source of infection. It requires thousands of spores to cause human infection.
•
anthrax does not spread from human to human.
anthrax infection can occur in three forms:
• cutaneous
(skin), gastrointestinal (by ingestion) and pulmonary (by inhalation).
In
• cutaneous anthrax bacteria enter through skin cuts and wounds.
a skin lesion begins as a
• papule and soon becomes a vesicle and breaks, discharging bloody serum.
The seat of this vesicle, in about 36 hours, becomes a
•
bluish-black necrotic mass (dead tissue). It consists of minute particles rich in spores.
Gastrointestinal anthrax
• is caused by taking under-
cooked meat of infected animals. Patient experiences chill, hi
• gh fever, body aches, nausea,
vomiting, bloody diarrhoea, loss of appetite, and frequently haemorrhages from the mucous membranes and in the skin.
Pulmonary anthrax
• is acquired by inhaling dust
containing B. anthracis. Initial symptoms
• resemble those of common cold. Later there is difficulty in breathing, cough, fever, fast pulse and cardiovascular collapse.
Pulmonary anthrax is often called wool-sorter’s disease. •
If left untreated, anthrax in all forms can lead to
•
septicemia and death.
Death is apparently due to oxygen depletion, secondary
•
shock, increased vascular permeability, respiratory failure and cardiac failure.
Bacillus anthracis
• can be easily grown in the laboratory.
anthrax spores can be produced in a dry form which can be stored as particles.
These particles can be used in
• biological warfare.
Spores are infective in dry form, not in wet form. Tuberculosis
Tuberculosis (Tb), also called
• Koch’s disease is caused by rod
shaped Gram +ve bacteria, Mycobacterium tuberculosis.
The bacterium releases a toxin,
• tuberculinwhich destroys
the organs it infects.
It affects the lungs, lymph nodes, bones and joints.
•
It spreads through sneezing, coughing, contaminated food
•
and water.
Incubation period is 3 to 6 weeks or may be years.
•
Constant cough and in severe cases sputum with blood,
•
pain in chest while coughing, loss of body weight, failure of appetite, slight rise of temperature in the evening are the symptoms of lung T. b.
bCG (bacillus Calm
• ette Guerin) vaccine for Tb was obtained from bovine bacillus by Calmette and Guerin in 1921. Sputum, tuberculin, X-ray
• and gastric analysis are
carried out to diagnose tuberculosis. Tuberculin test is also called
• Mantoux test.
Direct observation treatment
• (DOT) is a programme
under WHO for treatment of Tb across the world. Whooping cough (Pertussis)
Who
• oping cough is caused by Bordetella pertussis and is a common childhood disease affecting the respiratory system.
It spreads by droplet infection or by direct contact.
•
It has an incubation period of 10 - 16 days.
•
It causes constant cough leaving the child breathless, tired
•
and red in face. L
• ater the voice becomes hoarse and the cough gives a whoop or a loud crowing sound while inhaling.
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February ’13The child usually vomits and there is frothy discharge from
•
his mouth and nose.
There may be complications like vomiting, convulsions and
•
pneumonia.
Immunisation of the diseas
• e is done by DPT vaccination.
Cholera
Cholera commonly calle
• d haiza is a water-borne disease
caused by the bacterium, Vibrio cholerae.
robert Koch discovered this disease. •
Incubation period varies from a few
• hours to 2–3 days.
It spreads through contaminated food and drinks.
•
The causative bacterium secretes cholera toxin,
•
enterotoxin which induces excessive secretion of an isotonic electrolyte solution by the intestinal mucosa. This solution is lost in stool.
Cholera is mainly characterized by sudden onset of
•
profuse, effortless, rice-water like stools, vomiting and rapid dehydration, loss of minerals and muscular cramps.
Fluid and salt lost is restored by
• oral rehydration solution (OrS). It is water with a small amount of sugar and salt. Cholera vaccine is effective for six months only.
•
Proper
• sanitation and hygienic conditions are the best methods of prevention.
Leprosy (Hansen’s disease) Leprosy is a
• contagious chronic bacterial disease caused by Mycobacterium leprae which is characterised by the chronic infection of the skin and other tissues.
The incubation period is very long and averages 2-5
•
years.
Infection occurs by prolonged contact with leprosy
•
patients.
The bacilli leave the body in nasal discharge, from the
•
throat during coughing, sneezing and even speaking and through broken skin lesions.
Symptoms of leprosy include appearance of
• light coloured
patches on the skin, thickening of the nerves, partial or total loss of sensation in the affected parts of the body.
These are accompanied by fever, pain, ulcers and skin
•
eruptions. Deformities of toes and fingers may also develop.
It is of two types :
• tuberculoid leprosy involving
tuberculoid granulosus formed by aggregation of macrophages and lepromatous leprosy characterised by nodular aggregates of lipid laden macrophages, lepra cells.
Presence of lepromin
• in skin test can indicate the
appearance of leprosy.
Tuberculoid leprosy gives
• positive test with lepromin
while lepromatous leprosy is negative to lepromin test. Leprosy is curable. No vaccine is available
•
Tetanus (Lock jaw)
Lock jaw disease is caused by the spores of
• Clostridium
tetani that enter through wounds.
Its infection is acquired by contamination of wounds with
•
tetanus spores as these infected spores are abundant in the soil manured with animal dung.
Spores may survive for 60 or more years in contaminated
•
soil.
Incubation period is of 3-25 days during which the
•
bacterium secretes a powerful exotoxin tenanospasmin
into the tissue, and blood carries it to the central nervous system and brings about tetanus of muscles.
The
• symptoms are painful muscular spasms especially of neck and jaw.
Lock jaw
• condition occurs when the patient cannot open the mouth, convulsions and paralysis of muscles, difficulty in chewing and swallowing, fever and headache also occur.
all wounds should be treated carefully and cleaned
•
with iodine solution. Tetanus toxoid injection should be administered in case of an injury.
Immunisation of infants by
• DPT or triple vaccine helps
in immunity against diphtheria, pertussis and tetanus. PrOTOzOAn DIseAses
Protozoans are diverse gro
• up of eukaryotic, unicellular
organisms.
Human diseases caused by protozoa are relatively few, but
•
are individually of devastating consequences. Types of protozoan diseases are
• amoebiasis, malaria,
african sleeping sickness, kala-azar, ciliary dysentery etc. Amoebiasis or Amoebic dysentery
amoebiasis is a
• protozoan infestation of upper part of large intestine which is caused by monogenetic protozoan (having one host) known as Entamoeba histolytica.
There is one host
• i.e., man.
The infection occurs by the cysts of
• Entamoeba present in
the stool of infected person.
Inside the intestine, the cyst germinates and releases
•
4-8 Entamoebae where they secrete an enzyme called cytolysin.
The enzyme partially dissolves the wall of large intestine.
•
The feeding stage of parasite is called
• trophozoite or
magna. It stops feeding prior to cyst formation.
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February ’13 53 The nonfeeding pre-cystic stage is called• minuta form.
amoebiasis
• results in ulceration of the intestines and occasionally in the formation of abscesses in the liver (amoebic or tropical abscesses), lungs, testes, or brain. Symptoms
• appear days or even years after infection and include pain in abdomen, diarrhoea, indigestion, loss of weight, and anaemia.
To prevent the infection, the sanitary disposal of faecal
•
matter and cleanliness in the preparation of food should be carefully done.
Malaria
Malaria is caused by a
• digenetic (have two hosts to complete its life cycle) and triphasic(having three phases of life cycle) protozoan parasite known as Plasmodium. The primary host is female
• Anopheles mosquito and
secondary host is man. Sir Ronald Ross
• (1897), a doctor in Indian army, established that malarial parasite is transmitted by the bite of a female Anopheles mosquito for which he got Nobel Prize in 1902.
The malarial parasite,
• Plasmodium enters the human
body as sporozoites (infectious form) through the bite of infected female Anopheles mosquito.
The sporozoites reach the liver cells
• via blood where they
initially multiply. These then attack the red blood cells (rbCs) resulting in their rupturing.
The rupture of rbC is associated with the release of
•
haemozoin, a toxin which causes the chill and high recurring fever every three to four days.
The female
• Anopheles mosquito when bites an infected
human being, the malarial parasites enter into the mosquito’s body and undergo further development to form sporozoites that finally move to the salivary glands of the insect.
The bite of these mosquitoes introduces the sporozoites
•
inside the body, thus initiating the above mentioned cyclic process again.
The attack of malaria is preceeded by yawning, tiredness,
•
headache and muscular pain. There are four species of
• Plasmodium which causes four
main types of malaria in human. They are
Plasmodium vivax
– : Benign tertian malaria in
which fever recurs after every 48 hours.
P. malariae
– : Quartan malaria in which fever appears after every 72 hours, and often produces persistent subclinical malaria.
P. falciparum
– : Cerebral malaria or malignant tertian malaria where fever recurs after every 48 hours.
P. ovale
– : Causes mild tertian malaria. The incubation period of
• Plasmodium ovale and P. vivax is
about 14 days, 12 days for P. falciparum and 28 - 30 days for P. malariae.
black water fever ca
• used by infection of P. falciparum results in the excretion of haemoglobin in urine.
Malaria is
• characterised by fever at intervals, sudden acute chilliness (cold or rigor stage) accompanied by shivering followed by rise in temperature.
Peak fever (hot or febrile stage) is 41.1°C or 106°F which
•
persists for 3-6 hours. after 2-4 hours of fever, there is profuse sweating (sweating or defervescent stage) which lowers the body temperature to near normal.
Malaria is also accompanied by nausea, headache,
•
laziness and muscular pains. It also results in anaemia and splenomegaly.
Clinical fever in malaria is due to
• erythrocytic schizogony.
Drugs like
• chloroquin and primaquin are administered to treat malaria.
Other drugs like
• quinine obtained from the bark of
Cinchona plant, camoquin, daraprim and artemesenin obtained from Artemesia annua (is effective against cerebral malaria) are also used to treat malaria.
Spreading areas with
• DDT, BHC and other insecticides.
introducing Utricularia, ducks and larva eating fishes like
Gambusia, stickle back minnow and trout in larger water reservoirs, putting oil (kerosene) in the water ponds can help to protect against the breeding of mosquitoes. African sleeping sickness (Trypanosomiasis)
Trypa
• nosoma is a flagellate protozoan whose different species causes different types of trypanosomiasis. It is of two types :
•
Gambian (W. african) sleeping sickness
– caused by
Trypanosoma gambiense by the bite of the blood sucking tse tse fly, Glossina palpalis.
rhodesian (e. african) sleeping sickness
– caused by
Trypanosoma rhodesiense by the bite of the tse tse fly, Glossina palpalis and Glossina morsitans. Trypanosoma
• is a protozoan which is digenetic having two hosts : Primary host – : man. antelope as – reservoir host. Secondary host
– : tse tse fly, Glossina palpalis.
The parasite lives in the blood stream and in the lymph, it
•
invades the cerebrospinal fluid of the CNS causing fever, anaemia, lethargy and death.
The infection is initiated by the bite of tse tse fly which
•
harbours the infective metacyclic forms in the lumen of its salivary glands.