C3.2 Defence against Diseases

What are pathogens.

Pathogens refer to the living organisms that cause diseases.

What are primary defence of pathogens for humans

Skin and

Mucous membrane (moist, linner lining of a body which is exposed to outside, such as lungs, nose and stomach)

Mucous produced by the membrane contains many lysozyme enzyme which kills many bacteria

Explain the clotting process

1. The platelets are attracted to the wounded tissues,

2. The platelets releases clotting factors

3. The Clotting factors initiate a cascade of reactions (products of a reaction is an enzyme for the next reaction to take place)

4. This ensures that the clotting happens only when its neccesary and it happens rapidly.

5. The penultimate reactions produces thrombin

6. Thrombin converts fibrinogen (soluble plasma protein), into long protein fibre called Fibirin

7. Fibrin forms a mesh of fibres across wounds.

8. Blood cells are caught in the mesh and form semi-solid clot

9. When the clot is exposed to air, the clot forms scab which prevents pathogen from entering the body.

Compare and Contrrast innate immune system and adaptive immune system

Innate immune system is

• non-specific

• Chemical, physical and cellular defence

• fast and does not last long

Adaptive immune system is

• specific

• takes longer to acquire but lasts long

Describe the function of Phagocytes

1. Phagocytes are cells in innate immune system

2. Have amoeboid movement from blood to the site of infection.

3. Then the phagocytes detects pathogens and engulf them to by endocytosis.

4. The pathogens in phagocytes are digested with lysosomes.

Describe the function of lymphocytes 

Lymphocytes are in adaptive immune system that cooperate to produce Antibodies

Lymphocytes circulate in blood and contained in lymph nodes.

B-lymphocytes are abundant and used to produce many types of antibodies.

What is a function of Memory cell and Plasma cell produced from B - lymphocytes.

Memory cell’s function is to

remember

• the antigens

• how to produce respective antibodies.

Also to

• stay in body as long as possible.

Plasma cell’s function is to

• Produce as many antibodies as possible.

Explain How the immunity works in mammals.

1. B - lymphocytes are activated by T - lymphocytes 

2. Activated B-lymphocytes multiply and differenciate into clones of plasma cells and memory cells.

3. Once the pathogen is marked with antibodies, the pathogen such as bacteria is destroyed by phagocytes by phagocytosis.

How is HIV, transmitted and what are the effects of the HIV.

HIV is transmitted through body fluids such as

• Blood

• Salaiva

• Semen

• Breast Milk

Effects of HIV are

1. reduces the number of T- lymphocytes and

2. causes the loss of ability to produce antibodies

This leads to a Acquired immune deficiency syndrome(AIDS).

AIDS is characterized by immunosuppression that gives raise to

1. infection,

2. tumours

3. central nervous system degeneration.

What is antibiotics and explain how bacterium can develop the resistance to it.

How Antibiotic works

Antibiotics are chemicals produced by living organisms (fungi) or produced synthetically.

They block processes that occur in prokaryotes but not in eukaryotic cells.

How bacterium can develop resistance to them

some bacterium mutate and develop the resistance to said antibiotics. And due to the selection pressure, the bacterium with resistance survive and eventually the ones with resistance grow in numbers.

What is Zoonosis

Zoonoses are animal infections that can reach humans through different modes,

Such as COVID-19, Tuberculosis, Rabies and Japanese encephalitis.

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