ملخص علوم بالانجليزى الدرس الثانى والاخير للصف الثالث الاعدادى

Science For Third Prep - Term Two - Lesson 2 : Immunity

Lesson (2)
Immunity

Immunity:
* The immune system of the human body:

- Is a specific defense system by which man can live in natural environment without attacking of microbes.
* The function of the immune system:
- To recognize any Microbes the body and to get rid of it.
* The immune system includes:
A- Natural immunity
B- Acquired immunity.

[A] Natural immunity:

- depend on the means of body:
1- The horny layer of the skin with sweat and fat excretions.
2- Cilia that cover the inner surfaces in the respiratory system.
3- The body excretions such as tears, mucus, acidic juice and some enzymes.
4- The white blood cells, they engulf or kill microbes.

- Factors that support natural immunity:
1- The genetic factors.
2- The breast feeding of new-borns, because the mother's milk contains antibodies.
3- Balanced complete nutrition.
4- Rest and sleeping.

- Factors that reduce natural immunity:
1- Exposure to radiations.
2- Drugs and alcohol.
3- Smoking.

Acquired Immunity:
A- Natural acquired immunity:
- It originates after the body is subjected to a disease.
- The body produces antibodies and cells which attack the microbe "Lymphocytes".
- Some of which produce antibodies and the others activate other blood lymph cells until the immune system is activated.

B- Artificial acquired immunity:
- Immunity can be acquired through vaccination by:
- Vaccine.
- Serum.

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

* Antibiotics:
- They are chemical compounds produced by living micro-organisms to stop the growth or cause death of some other micro-organisms.

- How are antibiotics applied?
- Antibiotics are applied after number of experiments and tests of their effect range on.
1- The white blood cells.
2- The body tissues.
3- The biological process such as "respiration and blood circulation".

- The side effects of using antibiotics:
1- Sensitivity like itching and skin rash.
2- Disturbance in the nervous system.
3- Symptoms of toxication with overdoses.

- Some other uses of antibiotics:
1- Food preservation in concentrations which are not harmful to man's health.
2- For controlling plant diseases by spraying their solutions on fruit crops.

* Side effects of using antibiotics without prescription:
1- Decreasing of the natural immunity against microbes.
2- Production of antibiotic resistance strains of the microbe, this well make treatment ineffective.
3- Over sensitivity on various body systems.
4- Using more than one antibiotic at the same time may result in one of them stopping the effect of the other