Immune system Flashcards
Assaults on the body
- external: microorganisms, protozoans, bacteria, and viruses
- internal: include abnormal cells that reproduce and form tumors that may become cancerous and spread
Immune system organization
- Antigens
- Self vs no self
- Innate immunity / non specific
- Adaptive immunity / specific
QAntigens
q- a protein marker on the surface of cells to identify them
- stimulate the production of antibodies
- immunocompetence: the ability to activate an effective response to a foreign antigen
Self markers
Molecules on the surface of human cells that are unique to an individual, thus identifying the cells as self to the immune system
- MHC: major histocompatibility complex
Non-self markers
Molecules on the surface of foreign or abnormal cells or particles that identify the particle as “non-self” to the immune system
Self-tolerance
The ability of our immune system to attack abnormal or foreign cells, but spare our own normal cells
Innate immunity / nonspecific
Present at birth
- built in and ready for action providing the initial defense mechanism
Adaptive immunity / specific
Mechanisms that develop in response to specific threatening agents or specific abnormal cells
Cytokines
Broad and loose category of small proteins that are important in cell signaling
- they are released by cells and affect the behavior of their cells or the cells that release them
- regulate or initiate innate and adaptive immunity
- ex: interleukins, leukotrienes, and interferons, growth factors
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Innate immunity: mechanical and chemical barriers
First line of defense is the skin and mucous membranes
- sebum, mucus, enzymes, and hydrophobic acid in the stomach
Innate immunity: inflammatory response
Provides a second line of defense
- tissue damage - release of inflammation mediators (histamine, kinins, prostaglandins, leukotrienes, and interleukins)
- many of these mediators are chemotactic factors: substances that attract WBCs to area (chemotaxis)
Innate immunity: inflammation
Due to increased blood flow and vascular permeability in the affected region, which help phagocytosis WBCs reac the general area and enter the affected tissue
- redness - warmth - pain - edema
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Innate immunity: phagocytosis
- a major component of second line of defense (but also plays role in adaptive immunity)
- the ingestion and destruction of microorganisms or their small particles by phagocytes
- cells that perform this funciton are called antigen-presenting cells
APC
Antigen-presenting cells
- phagocytes that ingest foreign particles, isolate protein segments (peptides), and display them as antigens on their surfaces
- these peptides are then recognized by cells of the adaptive immune response by a specific (adaptive) immune cell
Neutrophils
Most numerous; first responder
Macrophages
Large eaters
- phagocytes monocytes that have grown to several times their original size after migrating out of the blood stream
Dendritic cells
Cells with many extensions
- found in many body tissues that are in contact with the external environment, such as the skin and mucous membranes