HUMAN HEALTH AND DISEASE
- Improper functioning of one or more organs or systems of the body is adversely affected, gives rise to various signs and symptoms i.e we have disease.
- Diseases which can easily transmit from one person to other by any means are called infectious or communicable diseases.
- Diseases which can not be transmitted from one person to another are called non-infectious or non-communicable diseases.
- Disease causing organisms are said to be pathogen.
TYPHOID:
Pathogen: Salmonella typhi (bacterium)
Organs affected: small intestine, migrate to other organs through blood.
Method of transmission: contamination of food and water.
Symptoms:
- Sustained high fever (39o to 40o C)
- Weakness, stomach pain, constipation, headache and loss of appetite.
- Intestinal perforation and death may occur.
Test: Typhoid fever could be confirmed by Widal test.
PNEUMONIA:
Pathogen: Streptococcus pneumoniae and Haemophilus influenzae.
Organs affected: Alveoli of lungs, alveoli get filled with fluid.
Method of transmission: inhaling the droplets/aerosols released by infected person. Sharing glasses and other utensils.
Symptoms:
- Fever, chills, cough and headache.
- In severe cases the lips and finger nails turn gray to bluish colour.
COMMON COLD:
Pathogen: Rhino viruses.
Organs affected: nose and respiratory passage
Method of transmission:
- Direct inhalation of droplets from infected person.
- Through contaminated objects like pen, books, cups, computer key board.
Symptoms:
- Nasal congestion and discharge, sore throat, hoarseness, cough.
MALARIA:
Pathogen: Plasmodium. (P. vivax, P. malariae, P. ovale, P. falciparum)
Malignant malaria caused by P. falciparum is fatal.
Organs affected: liver, RBC.
Method of transmission: by biting of female anopheles mosquito (vector)
Symptoms: high fever and chill, fever occurs on every alternate day, vomiting.
life cycle of malaria parasite:
- Life cycle of plasmodium starts with inoculation of sporozoites (infective stage) through the bite of infected female Anopheles mosquitoes.
- The parasite initially multiplied within the liver cells and then attack the red blood cells (RBCs) resulting in their rupture.
- There is release of a toxic substance called hemozoin from the ruptured RBCs which responsible for the chill and high fever.
- From the infected human the parasite enters into the body of Anopheles mosquito during biting and sucking blood.
- Further development takes place in the body of Anopheles mosquitoes.
- The female mosquito takes up gametocytes with the blood meal.
- Formation of gametes and fertilization takes place in the intestine of mosquito.
- The zygote develops further and forms thousands of sporozoites which migrated into the salivary gland of mosquito.
- When the mosquito bite another human sporozoites are injected.
- The malarial parasite requires two hosts – human and Anopheles, to complete their life cycle.
CBSE Biology (Chapter Wise) Class XII ( By Mr. Hare Krushna Giri )
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