Preventing Entry of Pathogens and the Non-specific Immune Response

Question 1

What is a macrophage’s role? What is a macrophage? What is it involved in?

Answer 1

• a macrophage is a type of white blood cell that engulfs bacteria and other foreign matter in the blood and tissues (and initiating an immune response)
• it is a phagocyte (along with neutrophils)
• it is involved in innate immunity

Question 2

What is a neutrophil’s primary function? What is a neutrophil? What are they involved in?

Answer 2

• a neutrophil’s primary function is to prevent infections in the body by engulfing and destroying invading pathogens
• it is a phagocyte (along with macrophages)
• it is involved in innate immunity

Question 3

What is the definition of inflammation?

Answer 3

• inflammation is a local response to infection and tissue damage

Question 4

What does the inflammatory response help to do?

Answer 4

• the inflammatory response helps to destroy invading microbes

Question 5

What chemical do damaged white blood cells and mast cells release at the site of an inflammatory response? What does this chemical cause?

Answer 5

• damaged white blood cells and mast cells (found in the connective tissue below the skin and around blood vessels) release histamine
• histamine causes the arterioles in the area to dilate, increasing blood flow in the capillaries at infected site

Question 6

What do histamines increase? What does this cause? How does this lead to oedema? What does this result in?

Answer 6

• histamines increase the permeability of the capillaries
• this causes cells in the capillary walls to separate slightly, so the vessels leak
• plasma fluid, white blood cells and antibodies leak from the blood into the tissues causing oedema (swelling)
• this results in the infecting microbes to now be attacked by these intact white cells

Question 7

What is an interferon?

Answer 7

• interferons are (antiviral) proteins released by host cells in response to the presence of pathogens such as virus, bacteria, parasites or tumor cells

Question 8

What is phagocytosis?

Answer 8

• phagocytosis is a process wherein a cells binds to a particle it wants to engulf on the cell surface and draws the item inward while engulfing around it
• (phagocytosis / “cell eating” is the process by which a cell engulfs a particle and digest it)

Question 9

What is a lysozyme? Is it used in a specific or non-specific response? Suggest how a lysozyme might break down bacterial cell walls?

Answer 9

• a lysozyme is an enzyme that kills bacteria by breaking down their cell walls
• they are used in non-specific responses
• the enzyme lysozyme can break down bacterial cell walls by hydrolysing the polysaccharide

Question 10

What does oedema refer to? What is it caused by?

Answer 10

• oedema is the medical term for swelling
• it is caused by a build-up of fluid in the spaces between your cells

Question 11

What is the difference between non-specific and specific responses?

Answer 11

• non-specific responses help to destroy any invading pathogen, whereas specific immunity is always directed at a specific pathogen

Question 12

At the infected site, what attracts phagocytic white cells? What are first to arrive and what do they do? What arrives next and what do they do?

Answer 12

• chemicals released by bacteria and the cells damaged at the site of infection attract phagocytic white cells
• neutrophils are the first to arrive, they engulf between 5 and 20 bacteria before they become inactive and die
• the neutrophils are followed by macrophages. These larger, longer-lived cells each have the potential to destroy as many as 100 bacteria by phagocytosis

Question 13

What is innate immunity? Is it a specific or non-specific response?

Answer 13

• innate immunity response is the first line of defence against pathogens
• it is a non-specific response that occurs immediately

Question 14

What is an antigen?

Answer 14

• an antigen is a substance capable of stimulating an immune response
• they tell your body that something is foreign
• any molecule the body recognises as not being of it’s own self

Question 15

What is an antigen?

Answer 15

antigens are:
- chemicals on the surface of a cell such as proteins, glycoproteins or carbohydrates
- toxins made by bacteria
- whole microogranisms e.g. bacteria/ virus
- antigens identify a cell as either ‘self’ (your own cells) or ‘non-self’
- non specific immune responses recognise the difference between self and non-self cells and react against anything that is non-self