7: Innate Immune System (2nd Line of Defence)

Question 1

2nd line of defence consists of (4)

Answer 1

• inflammation response
• phagocytosis
• lymph system
• cell death to seal off pathogen

Question 2

2nd LOD - inflammation resp (overview)

Answer 2

1. When cells are infected/injured, mast cells release histamines
2. Histamines cause blood vessels to dilate (vasodilation) -> increase blood flow to SOI -> red, hot + swollen (may kill path)
3. Hist also makes capillary wall more permeable to phagocytes so they can engulf invading path

Question 3

2 types of phagocytes are

Answer 3

• neutrophils
• macrophages

Question 4

neutrophils in 2nd LOD

Answer 4

• first ones to be called upon + move to SOI to inactivate path
• short acting self-destruct after a few days
• used by body to fight acute (short, severe) infections

Question 5

macrophages in 2nd LOD

Answer 5

• long-lasting - can either stay in the tissues or travel from the blood vessels into the infected tissues
• used by the body to fight chronic, long lasting infections
• after the macrophage has destroyed the foreign particle, parts of the antigen are displayed on the surface of the macrophage

Question 6

2nd LOD phagocytosis

Answer 6

1. Phagocytes recognise pathogens
2. Engulf path + destroys them with lysosomes

Question 7

lymph syst 2nd LOD

Answer 7

• Bacteria + other microbes picked up in lymphatic fluid and trapped inside lymph nodes
• In LN: attacked + destroyed by macrophages (swollen lymph nodes glands are a good indicator of infection)

Question 8

expl behind cell death in 2nd LOD

Answer 8

If a wall of dead cells surrounds the infected cells, it prevents the infection from spreading to other areas and infecting them

Question 9

comp innate vs adap imm syst

inn

Answer 9

• non-specific response
• no memory
• 1st and 2nd LOD
• rapid response rate

Question 10

mast cell

Answer 10

• induces inflammation through release of histamines + heparin -> dilates blood vessels

Question 11

basophil

Answer 11

• responsible for defense against parasites
• releases histamines that cause inflammation + may be responsible for allergic reactions

Question 12

eosinophil

Answer 12

releases toxins that kill bacteria + parasites
but
also causes tissue damage

Question 13

2nd LOD inflammatory resp (the full)

Write out

Answer 13

1. First line of defence breached + pathogens enter
2. Mast cells send out histamine molecules → causes vasodilation → increased blood flow to site of infection → red + hot
3. Histamines + other inflammatory chemicals increase permeability of nearby capillary walls/blood vessels → easier for phagocytes to enter + nearby capillaries release protein-rich fluids → swelling
4. Leaked protein helps clot blood + form scabs (clotting elements)
5. Lymphatic system sucks up + filters extra fluid before it goes back into the bloodstream
6. If more foreign invaders than WBCs + macrophages can handle, they let loose pyrogen chemicals that tap the hypothalamus + raise the body’s temperature → fever = burn everything