Immune system

Question 1

Name some components of the innate immune system

Answer 1

The innate immune system is the first line of defence against infection. It protects from all foreign pathogens. But the protection is not-specific.

(List is not comprehensive)

Mechanical barrier – skin

Body fluids - gastric acid, tears

Cough reflex

Immune cells - macrophages, neutrophils

Proteins – complement

Question 2

What are the major benefits of the innate immune system?

Answer 2

Innate immune system is always “active” trying to prevent infection

If infection does occur, the innate immune system acts to clear the infection promptly, or stimulates the adaptive immune response for a more rigorous immune response

Question 3

What are the limitations of the innate immune system?

Answer 3

The innate immune system is non-specific, and so although it fights most invaders well, some pathogens will be able to evade these defences

There is no “memory” of any previous infections. Therefore an infection does not provide protection against any subsequent infections

Question 4

What is the adaptive immune response?

Answer 4

Second line of defence against infection.

After a pathogen has breached the innate defence system, then the adaptive immune system is stimulated.

This response consists of B-cells producing antibodies to neutralise pathogens, and T-cells activating to seek out and destroy invading pathogens

Question 5

What are the benefits of the adaptive immune system?

Answer 5

The pathogen triggers an immune response, which is targeted at that specific pathogen. So in theory, should be more effective at help clearing the infection

Memory - following an infection, memory B-cells are created. This means that any subsequent infection, by the same organism, should have a quicker and stronger immune response

Question 6

What are the drawbacks of the adaptive immune system?

Answer 6

This takes time to fully activate >1 week. During this intervening time, an infection can cause serious damage, and could potentially be fatal

Memory loss - the immune system can weaken over time due to aging, or due to drugs which cause immunosuppression. This can mean that infections that a person was previously immune to, can become susceptible again in the future