Non Specific Immune Reponse

Question 1

What is the secondary defence called?

Answer 1

Phagocytosis

Question 2

What are phagocytes?

Answer 2

White blood cells made in the bone marrow

Two types:
1. Neutrophils
2. Macrophages

Question 3

Describe neutrophils

Answer 3

• most abundant WBC in humans
• travel in the blood and can squeeze through the walls of blood vessels to get to sites of infection
• short lived tend to die after engulfing bacteria
• have a multilobed nucleus (so it’s flexible to move to site of infection)
• numbers rise as a result of infection

Question 4

Describe macrophages

Answer 4

• long lived - survive after engulfing bacteria
• able to “present” specific antigens of pathogens it has digested
• mostly found in the lymph nodes, spleen, lunge and liver
• important in the initiation of B and T cell responses because of their role in antigen presentation

Question 5

Describe phagocytosis

Answer 5

1. Chemical products of pathogens or dead and abnormal cells act as attractants, causing phagocytes to move towards pathogen
2. Phagocytes have several receptors on their cell surface membrane that can attach to pathogens
3. They engulf the pathogen to form a phagosome
4. Lysosomes move towards and fuses with the phagosome to form a phagolysosome
5. Lysozymes hydrolyse the pathogen into soluble products that are absorbed in the cytoplasm
6. In cases of macrophages, some of the products are presented on the cells surface membrane (antigen presentation). This is important in the initiation of a T or B cell response