Immunology 1

Question 1

What is the function of the immune system? (2)

Answer 1

• It is the system that eliminates harmful micro-organisms such as viruses and bacteria
• It is the system that eliminates harmful substances such as toxins.

Question 2

What is variolation?

Answer 2

The administration of an organism that causes disease by an alternative method of administration, to provide immunity.

Question 3

Name the organs or anatomical structures activated in the “first line of defence” response. (5)

Answer 3

• Lymph nodes
• Spleen
• Lymphatics
• Bone marrow
• Skin

Question 4

Name the cells activated in the “first line of defence” response. (5)

Answer 4

• Neutrophils
• Monocytes/Macrophages
• Eosinophils
• Mast cells
• Lymphocytes

Question 5

Name the proteins involved in the “first line of defence” response. (6)

Answer 5

• Immunoglobulins
• Complement
• Cytokines
• Mucous
• Stomach acid
• Commensal bacteria

Question 6

What features of skin make it an effective barrier to infection?

Answer 6

• Tightly packed, highly keratinised, multilayered cells make it an effective physical barrier
• Low pH, most pathogens are sensitive to acidic environment
• Low oxygen tension
• Presence of sebaceous glands.

Question 7

What features do sebaceous glands possess in preventing infection, and describe these features? (4)

Answer 7

• Secrete hydrophobic oils to repel water and microorganisms.
• Lysosymes- Enzymes that destroy the structural integrity of bacterial cell walls.
• Ammonia- Anti bacterial properties
• Antimicrobial peptides such as defensins.

Question 8

What are the features of mucous in preventing infection and describe them? (4)

Answer 8

• Physical barrier to trap invading pathogens
• Secretory IgA antibodies that prevent bacteria and viruses attaching to and penetrating epithelial cells.
• Contains enzymes (e.g lysozymes), defensins and antimicrobial peptides to kill pathogens.
• Cilia trap pathogens and sweep mucous away to be removed (e.g by coughing or sneezing)

Question 9

Name some external factors that lead to breach of these constitutive barriers.

Answer 9

• Insertion of hardware (such as IV lines, catheters, NG tubes)
• Antibiotics which eradicate the norma flora in he body.
• Anti-acid medication used in gastro-oesophageal reflux and heartburn.
• Nasal decongestants which decrease mucous production
• Anti-bacterial wipes.