innate immune system

Question 1

three levels of defence against pathogens

Answer 1

1) anatomical/physiological barriers
2) innate responses
3) adaptive responses

Question 2

What makes up the anatomical and physiological barriers?

Answer 2

Structural defences: Epithelial tissue that create a barrier between the internal cavities of the body and the external environment:ex: Skin, gastrointestinal tract, urogenital and respiratory tracts, ciliated epithelial cells

Biochemical defenses: Examples: The skin is dry, and is a high salt environment. Anti-microbial peptides and proteins: Secretion of defensinproteins, cationic peptidesThe stomach secretes acid, lysozyme produced in saliva and tears; gastrointestinal and respiratory tracts secrete mucous.

Question 3

What is the function of primary lymphoid organs, what are they, and why they are different than secondary lymphoid organ?

Answer 3

• where leukocytes develop and mature
  bone marrow: platelets, RBCs, innate immune cells, B cells
  thymus: T cells
• primary lymphoid organs develop immune cells, secondary lymphoid organs bring blood in contact with lymphocytes and scans for infections

Question 4

What is the function of secondary lymphoid organs, what are they, and why they are different than primary lymphoid organ?

Answer 4

Spleen:
•Major function is to bring blood into contact with lymphocytes so that any blood-borne infections are noticed

Lymph nodes: include tonsils, adenoids, “glands”
•Bring contents of the lymph(extracellular fluid) into contact with lymphocytes, so that any infections in the tissues are noticed

Question 5

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

Answer 5

• innate is immediate and fast, non specific; adaptive is slower, but specific and more effective

Question 6

How are microbes recognized to initiate the immune response?

Answer 6

answer this

Question 7

The immune system comprises a network of cells including: (list the components of the innate and adaptive immune system)

Answer 7

Innate: neutrophils, macrophages, dendritic cells
Adaptive: T-cells and B-cells
(all derive from the hematopoietic stem cell)

Question 8

list the steps of the immune response:

Answer 8

1. Inflammation begins with damage to the tissue. Mast cells release histamine, which increases the permeability of blood vessels
2. Cells, proteins and fluid leak out
3. Pathogens activate macrophages, which release alarm cytokines and recruit more cells from the blood
4. Macrophages and neutrophils phagocytose & destroy pathogen
5. Coagulation proteins seal off the inflamed area, and complement proteins increase recruitment, phagocytosis and pathogen destruction

Question 9

phagocytosis

Answer 9

engulfment and internalization of materials such as microbes for their clearance and distinction

Question 10

What are cytokines?

Answer 10

small soluble proteins rapidly secreted by one cell that can alter the behaviour or properties of the cell itself or another cell (ex IL-2)

Question 11

What is a sign of a PAMP?

Answer 11

1. cell wall contains LPS or peptidoglycans
2. flagella
3. nucleic acid properties commonly found in bacteria or viruses

Question 12

Signs of a non-self microorganism?

Answer 12

1. not found in the host
2. present in pathogens
3. not frequently mutated
4. recognized by PRRs

Question 13

What does complement do?

Answer 13

1. Increases phagocytosis
   •“opsonization” –process where proteins “decorate” the bacteria to signal that it should be eaten!
   •C3b sticks to the bacteria and triggers phagocytes to eat it!

2.Lyses bacteria
•Membrane Attack Complex (MAC)
•C5b also sticks to the bacteria and initiates MAC formation

3. Recruits more cells to the infection site
   •Enhance blood vessel permeability
   •Promote histamine and TNFalpha secretion from mast cells and Macs
   •C3a and C5a products do this
   •C5a is also a neutrophil ‘chemoattractant’ (sticky)