Pathogens and the host: Innate immunity

Question 1

What is the role of the immune system?

Answer 1

To provide defence against foreign microorganisms

Question 2

What are 2 disadvantages of the immune system?

Answer 2

• cause discomfort to the host (inflammation)

- damage to self (autoimmunity) by recognising own cells as foreign

Question 3

What is the difference between the innate and adaptive immune system?

Answer 3

Innate: first line of defence, non specific, rapidly evoked
Adaptive: slow activation, specificity, memory

Question 4

Give 4 examples of innate mechanisms

Answer 4

1. anatomic resisting barriers such as skin (microbes killed by naturally produced antibiotics) and mucus
2. physiological barriers such as temp and pH
3. phagocytosis
4. inflammatory defensive barriers such as vasodilation

Question 5

Give 4 examples of soluble factors and what each does:

Answer 5

1. lysozyme - breaks bacterial wall
2. acute phase proteins - opsonisation, attraction of phagocytes, increased blood flow
3. complement proteins - opsonisation
4. interferons - toxic to viruses by cytokines (antiviral resistance)

Question 6

How are the cells of the innate immune system split?

Answer 6

the myeloid cells are split into granulocytic cells and monocytes cells.
Granulocytic include: Neutrophils, basophils and eosinophils
Monocytes include: Macrophages, Langerhans, Kupfer cells and dendritic cells

Question 7

Describe the monocyte:

Answer 7

large WBC with a horseshoe shaped nucleus and faint azurophilic granules

Question 8

Describe the macrophage:

Answer 8

they engulf (scavengers) and are APCs. Once stimulated, they exhibit increased levels of phagocytosis. Also involved in tissue repair

Question 9

Describe the Neutrophil:

Answer 9

They uptake. Most abundant WBC and relatively large with a lobed nucleus and lysosomes.

Question 10

Describe the Basophil:

Answer 10

should be a very small number in healthy humans. They have deep violet-blue coloured granules and are active in allergic reactions. releasing histamines.

Question 11

Describe the eosinophil:

Answer 11

these gather wherever there is an infection or an allergic reaction and release their toxins (which are in the granules). they are, just like basophils, important in allergic reactions and histamine.

Question 12

What are natural killer cells?

Answer 12

they recognise virus infected cells by secreting their own chemicals so don’t need to be activated by antigens

Question 13

What is the role of release factors?

Answer 13

to increase blood flow, bringing components of immunity to the site of infection such as neutrophils, phagocytes etc

Question 14

Which organism is resistant to phagocytosis?

Answer 14

Pneumococcus