Innate Immunity

Question 1

Innate Immunity

Answer 1

Nonspecific immune response made of defenses against infection that can be activated immediately once a pathogen attacks; made up of barriers that aim to keep viruses, bacteria, parasites and other foreign materials out of your body or limit the spread throughout the body
- anything identified as foreign or non-self is a target for this response; activated by the presence of antigens and their chemical properties

Question 2

What is the innate immune system composed of?

Answer 2

Physical barriers: skin, GI tract, respiratory tract, nasopharynx, cilia, eyelashes, and other body hair
Defense mechanisms: secretions, mucous, bile, gastric acid, saliva, tears and sweat
General immune responses: inflammation, complement, and non-specific cellular responses

Question 3

Antigen

Answer 3

anything that causes an immune response. Antigens can be entire pathogens, like bacteria, viruses, fungi, and parasites, or smaller proteins that pathogens express. Antigens are like a name tag for each pathogen that announce the pathogens’ presence to your immune system. Some pathogens are general, whereas others are very specific

Question 4

Cytokines

Answer 4

molecules that are used for cell signaling, or cell-to-cell communication. Cytokines are similar to chemokines, wherein they can be used to communicate with neighboring or distant cells about initiating an immune response. Cytokines are also used to trigger cell trafficking, or movement, to a specific area of the body

Question 5

Chemokines

Answer 5

type of cytokines that are released by infected cells. Infected host cells release chemokines in order to initiate an immune response, and to warn neighboring cells of the threat

Question 6

What is the inflammatory response?

Answer 6

Actively brings immune cells to the site of an infection by increasing blood flow to the area

Question 7

Complement

Answer 7

Immune response that marks pathogens for destruction and makes holes in the cell membrane of the pathogen

Question 8

Complement cascade

Answer 8

mechanism that complements other aspects of the immune response; made of a variety of proteins that, when inactive, circulate in the blood. When activated, these proteins come together to initiate the complement cascade

Question 9

What are the steps of the complement cascade?

Answer 9

1. Opsonization
2. Chemotaxis
3. Cell lysis
4. Agglutination

Question 10

1. Opsonization

Answer 10

A process in which foreign particles are marked for phagocytosis. All of the pathways require an antigen to signal that there is a threat present. Opsonization tags infected cells and identifies circulating pathogens expressing the same antigens

Question 11

2. Chemotaxis

Answer 11

The attraction and movement of macrophages to a chemical signal. Chemotaxis uses cytokines and chemokines to attract macrophages and neutrophils to the site of infection, ensuring that pathogens in the area will be destroyed

Question 12

3. Cell lysis

Answer 12

Lysis is the breaking down or destruction of the membrane of a cell. The proteins of the complement system puncture the membranes of foreign cells, destroying the integrity of the pathogen. Destroying the membrane of foreign cells or pathogens weakens their ability to proliferate, and helps to stop the spread of infection

Question 13

4. Agglutination

Answer 13

Agglutination uses antibodies to cluster and bind pathogens together; by bringing as many pathogens together in the same area, the cells of the immune system can mount an attack and weaken the infection.

Question 14

Cells of the innate immune system:

Answer 14

Leukocytes (WBCs) that protect and defend the human body; travel via the circulatory system

Question 15

Phagocytes

Answer 15

Circulate throughout the body looking for threats (bacteria/viruses) to engulf and destroy; security guards on patrol

Question 16

Macrophages

Answer 16

Efficient phagocytic cells that can leave the circulatory system by moving across the walls of capillary vessels. The ability to roam outside of the circulatory system is important, because it allows macrophages to hunt pathogens with less limits. Macrophages can also release cytokines in order to signal and recruit other cells to an area with pathogens.

Question 17

Mast cells

Answer 17

Found in mucous membranes and connective tissues, and are important for wound healing and defense against pathogens via the inflammatory response. When mast cells are activated, they release cytokines and granules that contain chemical molecules to create an inflammatory cascade. Mediators, such as histamine, cause blood vessels to dilate, increasing blood flow and cell trafficking to the area of infection. The cytokines released during this process act as a messenger service, alerting other immune cells, like neutrophils and macrophages, to make their way to the area of infection, or to be on alert for circulating threat

Question 18

Neutrophils

Answer 18

Phagocytic cells that are also classified as granulocytes because they contain granules in their cytoplasm. These granules are very toxic to bacteria and fungi, and cause them to stop proliferating or die on contact; typically the first cells to arrive at the site of an infection because there are so many of them in circulation at any given time

Question 19

Eosinophils

Answer 19

Granulocytes target multicellular parasites. Eosinophils secrete a range of highly toxic proteins and free radicals that kill bacteria and parasites. The use of toxic proteins and free radicals also causes tissue damage during allergic reactions, so activation and toxin release by eosinophils is highly regulated to prevent any unnecessary tissue damage; only make up 1-6% of the white blood cells, they are found in many locations, including the thymus, lower gastrointestinal tract, ovaries, uterus, spleen, and lymph nodes

Question 20

Basophils

Answer 20

Granulocytes that attack multicellular parasites. Basophils release histamine, much like mast cells. The use of histamine makes basophils and mast cells key players in mounting an allergic response

Question 21

Natural Killer (NK) cells

Answer 21

do not attack pathogens directly. Instead, natural killer cells destroy infected host cells in order to stop the spread of an infection. Infected or compromised host cells can signal natural kill cells for destruction through the expression of specific receptors and antigen presentation

Question 22

Dendritic cells

Answer 22

antigen-presenting cells that are located in tissues, and can contact external environments through the skin, the inner mucosal lining of the nose, lungs, stomach, and intestines. Since dendritic cells are located in tissues that are common points for initial infection, they can identify threats and act as messengers for the rest of the immune system by antigen presentation. Dendritic cells also act as bridge between the innate immune system and the adaptive immune system