Part 2

Question 1

What are the differences and similarities between the innate and adaptive immune system?

Answer 1

• Similarities:
• has both cell-mediated and secreted components
• Differences:
• innate occurs in all animals
• adaptive occurs only in vertebrates.
• Innate is a rapid response
• adaptive is a slow response
• innate is a generic response to pathogens
• adaptive is a specific response against pathogens
• in innate cells, type of response does not vary when infections reoccur ( no adaptions
• in adaptive cells, response occurs more rapid and efficient when infections reoccur (adaptation and memory)

Question 2

What are examples of anatomical barriers and what is their purpose?
- first line of defense

Answer 2

• skin, sclera, cornea, digestive track, epithelia tissues that are composed of lots of cells packed together. These are held together by close cell to cell contact, located on top of the basal lamina.
• epidermis is also multilayered and has dead cells (viruses can only infect live cells) on its outermost layers.
• the structure of epithelia tissues makes it a very good barrier to outside pathogens, fluid, etc.

Question 3

What are examples of physiological barriers?

- first line of defense

Answer 3

• tissues that secrete chemicals that serve as barriers to infection.
• EX: epithelial cells that secrete thick, sticky, mucous. This potentially traps any pathogens before that can reach the tissue. Then these are ciliated to be expelled through the mouth or digested in the stomach.
• Eyes secrete lysozyme, which is an enzyme that has antibacterial properties.

Question 4

What are examples of the second line of defense?

Answer 4

• granulocytes and phagocytes of the innate immune system that act as rapid cellular barriers to infection.
• Mast cells: their granules are full of histamines, that when released cause blood vessels to dilate and allow for increase blood flow.
• by delivering more blood to the sight of infection, you are in turn delivering more immune cells to the sight of infection
• Neutrophils:
• can do a little bit of both of these.
• technically granulocytes, but are also phagocytic.
• very good at using phagocytosis to kill potential pathogens, but they also contain granules that contain chemicals used for killing pathogens
• Macrophages:
• classic phagocyte, very good at recognizing bacteria and viruses in the environment and then using phagocytosis to deliver them to the lysosomes for degradation.

Question 5

Use the inflammatory response to demonstrate how the different lines of defense in the immune responses can interact with each other?

Answer 5

• Begins when a breach occurs in the epithelial tissues. (ex like a cut to the skin)
• Platelets begin the clotting process, but it is likely that some bacteria was able to get in the cut.
• the damaged cells in the area of the cut/infection attract macrophages to the sight, by sending out chemical signals-chemokine. Then the macrophages begin to secrete more chemicals which are more potent attractors to immune cells in that region.
• Some of these cells that will be drawn by the macrophages chemicals are Mast cells- release histamines which help dilate blood vessels and turn them more permeable.
• Neutrophils will also be attracted to the sight of infection and will remove pathogens via phagocytosis and degradation.
• Other leukocytes that arrive will mature and develop into new macrophages that again will assist in phagocytosis and the secretion of signaling molecules to the area that bring more signaling molecules to the area.

Question 6

Which phagocytic leukocytes carry out phagocytosis?

Answer 6

neutrophils, macrophages, dendritic cells.

Question 7

How do the phagocytic cells mentioned in lecture carry out phagocytosis without injuring normal cells?

Answer 7

• it has to do with their ability to bind to a wide variety of pathogen-associated molecular patterns (PAMPS)-molecules found on the surface of a broad category of pathogens that cells of the immune system recognize as foreign.
  ( EX: in bacteria, their cell walls are composed of peptidoglycan, eukaryotic cells don’t produce it, so if it is in their environment… good chance that it is bacteria.)
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Question 8

How do the phagocytic cells mentioned in lecture identify PAMPS?

Answer 8

• (PRRs) Pattern Recognition Receptors= classes of receptors found on innate immune cells and that recognize a particular category of PAMP
• ex: Toll-like receptors (TLRs)

Question 9

Describe the TLR4 example seen in class?

Answer 9

• TLR4 receptors are found in the plasma membrane of macrophages recognize LPS ( lipopolysaccharide, which is component of bacterial cell walls)
• So the TLR4 recognizes the PAMP or LPS and binds to it. This in turns creates a signaling response in the cell which then triggers the change in behavior.

Question 10

What is the complement system?

Answer 10

• composed of approximately 3 dozen proteins, many of which are produced by the liver then enter the blood stream. Most of the time these proteins don’t do much, but in response to a pathogen encounter they will secrete signals to activate any complement protein in that area.
  when activated:
• bind to pathogen, and make it a better target
  2.) they can attract more innate immune cells to the area
  3.) they can also basically attack the pathogen directly