Body Defences

Question 1

What are body defences?

Answer 1

• non-specific (innate) 1st and 2nd line

- specific (adaptive) - 3rd line of defence

Question 2

What are self cells?

Answer 2

• recognised by the immune system as being a normal part of the body by unique markers

Question 3

What are non-self cells?

Answer 3

• eg. pathogens, cancer cells, transplant tissue)

- contains markers or antigens that result in an immune reaction

Question 4

What is an antigen?

Answer 4

• anything that are recognised as ‘non-self’ by the immune system and so can cause a response
• eg. pathogens or part of the pathogens that are considered ‘antigenic’

Question 5

What are the general properties of non-specific?

Answer 5

• do not distinguish between threats
• react same each time as first time
• present at (before) birth
• 2nd line defences respond to tissue damage by pathogens or mechanical means

Question 6

Skin and skin glands.

Answer 6

• sebum inhibits growth of bacteria
• sweat can feed bacteria
• sensible perspiration contains an antibiotic agent
• CO2 changes pH of skin to acidic

Question 7

Interferons (IFNs).

Answer 7

• cytokines
• small proteins from macrophages and tissue cells infected by viruses
• signal other cells to defend themselves
• can be drugs - alpha-interferon

Question 8

Complement.

Answer 8

• proteins which kill bacteria

Question 9

Fever.

Answer 9

• high body temp (>37.2)
• speeds up defences
• slows down bacterial growth and viral replication

Question 10

Phagocytes.

Answer 10

• 2nd line of defence
• inside tissues
• fixed phagocytes reside in tissues
• free phagocytes move through blood (macrophages)

Question 11

Lymphatics.

Answer 11

• phagocytes travel through lymph vessels to lymph nodes

Question 12

Inflammation.

Answer 12

• non-specific defence mechanism

Question 13

Adaptive (specific) defence system

Answer 13

• 3rd line of defence - mounts attack against particular foreign substances

Question 14

What protects the body against antigens?

Answer 14

T cells and B cells

Question 15

What are T cells?

Answer 15

• manage the immune response

- attack and destroy foreign cells and infected cells

Question 16

What are B cells?

Answer 16

• produce plasma cells which secret antibodies

- antibodies immobilize antigens

Question 17

What are interleukins?

Answer 17

• increases T cell sensitivity
• stimulate B cell activity, plasma formation, antibody production
• enhance non-specific defences
• moderate the immune system

Question 18

What is TNF?

Answer 18

• tumour necrosis factors

- slows tumour growth

Question 19

What is CSF?

Answer 19

Colony Stimulating Factors

Question 20

What are 2 ways to activate B cells?

Answer 20

• phagocytes (APC) engulfs bacteria and presents antigens to helper T cells
• antigen attaches to antibodies on surface of B cells

Question 21

What is antibodies?

Answer 21

• made against antigens
• stay in blood and lymph nodes or attached to B cells
• can be measured in blood - titer
• 1 antibody type for each antigen

Question 22

What is IgG?

Answer 22

• major immunoglobulin in the blood

- able to enter tissue spaces; works efficiently to coat pathogens speeding destruction by other cells in immune system

Question 23

What us IgD?

Answer 23

• found inserted into the membrane of B cells where it somehow regulates the cell’s activation

Question 24

What is IgE?

Answer 24

• normally present in only trace amounts, but is responsible for the symptoms of allergy

Question 25

What is IgM?

Answer 25

• largest and first antibody to appear during the primary immune response

Question 26

What is immune memory?

Answer 26

• first exposure activates B and T cells
• memory cells formed
• memory cells react fast on second exposure - defeating antigen before disease

Question 27

What is vaccination?

Answer 27

• introduces antigen but not disease
• activates both arms - B and T cells
• response forms antibodies and memory cells