Overview of the immune system

Question 1

What is the immune system?

Answer 1

Immune system is body’s ability to resist or eliminate potentially harmful foreign materials (pathogens)

Question 2

What is the meaning of immunity?

Answer 2

Protection from infectious diseases

Question 3

What is a pathogen?

Answer 3

Any microorganism that causes harm

Question 4

What are the two main branches of immunity?

Answer 4

Innate
Acquired

Question 5

What is acquired immunity?

Answer 5

Production of antibodies.
Retain memory of pathogen invasion.

Question 6

What is innate immunity?

Answer 6

Ability to take action as soon as pathogen will infect us.

Question 7

What are some external barriers?

Answer 7

skin

mucus

flushing action

Epithelial cells of nasal passages and bronchi

Stomach

sweat

tears/salivia

Question 8

Differences between innate and adaptive immunity?

Answer 8

Innate- always present (ready to attack);
many pathogenic microbes have evolved to resist innate immunity
Adaptive- stimulated by exposure to microbe; more potent

Question 9

What are examples of components of innate?

Answer 9

phagocytes, complement and NK cells /natural killer cells

Question 10

Examples of components of adaptive immunity?

Answer 10

include mainly antibodies that are produced by B lymphocytes, and Cytotoxic cells that are differentiated from T cells

Question 11

Difference in response of innate immune response and adaptive immune response?

Answer 11

Innate:
Non-specific
Distinguishes between human cells and pathogens, but not between different types of pathogen
Fast and immediate: first to come into play
No memory: will produce the same response

Adaptive:
Highly specific
Distinguishes between different pathogens based on shapes on the surface – called antigens
Slower: Can take few days to develop
Immunological memory: memory cells remember

Question 12

What branches can we divide innate immunity into?

Answer 12

Cellular - Phagocytes, Eosinophils, mast cells and basophils

humoral - complement and cytokines

Question 13

What are phagocytes?

Answer 13

Phago: eating
Cyte = cell

are the cells of the immune system that track down, engulf and destroy bacteria, other pathogens as well as own damaged or dead cells.

Question 14

Describe characteristics of neutrophils?

Answer 14

Most abundant White Blood Cells (WBCs) (8x106/ml~50-60%)
Track down, engulf and destroy pathogens,
They contain granules that are filled with many destructive enzymes such peroxidases, alkaline and acid phosphates which are responsible for kill and destroy bacteria and other pathogens

Question 15

Describe characteristics of macrophages?

Answer 15

~5% of WBCs, larger than neutrophils
Can engulf much more
Macrophages (big eaters)
Break down pathogens, process specific components of these pathogens called antigens and present these processed antigens to the cells of the adaptive immunity to produce specific immune response in the form of Ab and cytotoxic T cells
Antigen Presenting Cells (APCs)

Question 16

Steps of phagocytosis?

Answer 16

Movement of the phagocyte toward the microbe

Attachment of microbes to phagocyte surface

Endocytosis of microbe and formation of phagosome

Fusion of phagosome with lysosome

Killing of microbe through digestion by enzymes

Discharge of waste materials