HUMAN HEALTH AND DISEASE

 

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 (39^o to 40^o 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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