Unit 4 - Immune System PART A Flashcards
Main function of the immune system organs/tissues/cells is to maintain homeostasis by:
a. recognizing and removing abnormal self-cells.
b. removing dead or damaged cells
c. preventing or limiting infections due to viruses, bacteria, fungi, parasites (protozoans and worms), allergens, etc.
Immune cells must be able to recognize cells that…
belong to the body (SELF), cells that are DEFECTIVE (e.g. cancerous cells) and cells that are not part of the body (NON-SELF).
“Self” cells
body’s normal cells
Defective cells
e.g. cancerous cells
Non-Self cells
viruses, bacteria, parasites, allergens, & other disease-causing PATHOGENS in addition to any of our own cells that have become defective & threaten to do harm, such as become cancer
First line of defense:
Physical, chemical and mechanical barriers.
- such as skin, tears, mucus & stomach acid
- attempt to keep pathogens from entering the ECF but…if pathogen gets past first line of defense barriers, next steps occur
If pathogen gets past first line of defense barriers, next steps are:
a. DETECTION and IDENTIFICATION of pathogen.
b. COMMUNICATION with other immune cells.
c. RECRUITMENT of assistance and COORDINATION of response.
d. DESTRUCTION or SUPPRESSION of pathogen.
Immunogens
substances that trigger the body’s immune response
Immunogens that react with products of the immune response are known as…
antigens
Internal response is carried out by _______ that communicate using _______ (which act as autocrine, paracrine and in a few cases hormonal signals)
LEUKOCYTES
CYTOKINES
Internal response is carried out by leukocytes that communicate using cytokines (which act as autocrine, paracrine and in a few cases hormonal signals). The internal response involves:
a. Macrophages (monocytes)
b. Dendritic Cells
c. Microglia (in the central nervous system)
d. Neutrophils
e. Mast Cells (from basophils)
f. Eosinophils
g. Natural Killer Cells
h. Lymphocytes (T and B Lymphocytes)
Cytokines
protein signal molecules released by 1 cell that affect the growth or activity of another cell
Immune system is also the primary user of ___________ that occurs when surface receptors on 1 cell recognize & bind to surface receptors on another cell
contact-dependent signaling
There are two major divisions of immune responses:
a. Innate immunity
b. Adaptive Immunity
Innate immunity
body’s EXISTING defenses that provide an IMMEDIATE, NON-SPECIFIC response (i.e. acts on anything identified as non-self) that is rapid acting (MINUTES to HOURS).
- Involves barriers to pathogens (physical, chemical, mechanical)
- Cellular responses that directly destroy or suppress the pathogen
- Characterized by INFLAMMATION
- Formation of antigen-presenting cells (macrophages and dendritic cells) which are required for both innate responses and adaptive responses.
- Not remembered by immune system (NO memory cells).
Inflammation
visible on the skin as a red, warm, swollen area
Cells responsible for the rapid innate response are…
circulating & stationary leukocytes that are genetically programmed to respond to a broad range of material that they identify as foreign
Some types of phagocytes display bits of digested pathogen on their cell surface to attract cells involved in the adaptive immune response –>
antigen-presenting cells (APC’s)
Describe this sentence in INNATE immunity: “Not remembered by immune system (NO memory cells)”
an innate response to a pathogen is NOT remembered by the immune system & must be triggered anew with each response
Adaptive Immunity (AKA acquired immunity)
LEARNED response to a SPECIFIC PATHOGEN/ANTIGEN; is SLOWER acting (days to weeks), but provides LONG LASTING IMMUNITY (MEMORY CELLS)
- Cell-mediated immunity
- Antibody-mediated (humoral) immunity
(both overlap; interconnected parts of a single process)
Describe this sentence ADAPTIVE immunity: “…but provides long lasting immunity (MEMORY cells)”
upon reexposure certain immune cells (MEMORY cells) “REMEMBER” their prior exposure to the pathogen & react more rapidly
Cell-mediated immunity (AKA humoral immunity)
contact dependent signaling (cytotoxic T-cells)
- uses ANTIBODIES
Antibody-mediated (humoral) immunity
production of antibodies by B lymphocytes and plasma cells
Antibodies
proteins secreted by immune cells, to carry out the immune response
- bind to foreign substances to disable them or make them more visible to the cells of the immune system
NOT all pathogens can be destroyed by the body’s immune system
- sometimes can just control the damage & keep the invader from spreading
ex: bacterium that causes tuberculosis, malaria parasite & the herpes viruses
Immunity
the body’s ability to protect itself
