Immunity/ week 2 Flashcards
Name 3 categories of pathophysiologic defense
- anatomic, biochemical barriers. IE: innate defense, things we are born with like skin, mucous membranes, coughing/sneezing reflex, GI/gut microbes
- inflammation, initiated when anatomic and biochem barriers are breached. Think laceration, infection, burn
- immune response. is specific, adaptive so NOT innate. results from inflammatory response, expose to invader. Think measles, chicken pox Can be natural response or intentional from vaccine. Consists both of Humoral and Cell-mediated response
Explain inflammatory response (brief)
Occurs when body barriers are breached. Blood vessels dilate so become more leaky/permeable. Movement of RBC, especially WBC, some fluids from blood to tissue when foreign invader is. WBC are activated by cytokines, become bound to internal vessel wall, squeeze through openings on cell wall. WBC now in tissue, can help macrophages attack invading microbes
Here is a 2 minute video: https://www.youtube.com/watch?v=iVCXRa8FdP0
Define chronic inflammation
Inflammation that last 2 weeks or longer (anything >2 weeks is chronic). Follows unsuccessful acute inflammatory response. Result: pus, incomplete wound healing. Can be related to type of bacteria present (gram (-) with tough lipid layer), toxins that survive macrophages, physical irritants/particulates like bad air pollution BUT also from autoimmune conditions like rheumatoid arthritis
Eventually, how does chronic inflammation harm the body?
Initial acute reaction continues to become chronic (vasodilation, inc blood flow, permeability and migration of WBC to infected tissue). Eventually WBC, macrophages and lymphocytes replace short-lived neutrophils. Ultimately area is dense with inflammatory cells (macrophages, lymphocytes, and plasma cells in tissue site) which produces inflammatory cytokines, growth factors, enzymes. Contributes to progression of tissue damage, fibrosis and granuloma formation
What is a cytokine?
Small protein involved in cell signaling. Due to size, cannot cross cell’s lipid bilayer, need a receptor on cel surface. Produced by immune cells like B-lymphocytes, T-lymphocytes, mast cells, macrophages. Have an role in immune system with healing, phagocytosis, controlling inflammation , cell differentiation. Can be made artificially, used to help body fight cancer, infections, diseases BUT over-secretion (“storm”) is dangerous, can lead to multi-organ failure, as seen in COVID deaths. Examples: interleukins, interferons
Name 3 plasma protein systems involved in immune response
- Complement: group of protein that cooperate, work in a cascade. Role in inflammatory cycle: Multiple functions including activating phagocytes, activating mast cells, inc enzyme activity.
- Coagulation: basically changes blood from liquid to a solid at site of injury by forming fibrin mesh. Role: Prevents spread of infection, forms clot, provides basis for wound repair
- Kinin: group of blood proteins assist inflammatory cells, most significant protein =bradykinin.
Role: Causes blood vessel dilation, smooth muscle contraction, inc vascular permeability.
CELLS IN IMMUNE SYSTEM: mast cells, basophils
(Note: basophils assumed to function very similar to mast cells)
Originate in bone marrow. Found in connective tissue, near skin surface and blood vessels. Can be activated physically, immune response, chemical injury to release inflammatory mediators such as histamine, cytokines, heparin
What occurs in mast cell degranulation?
When activated, can release selective or very rapid mediators that induce inflammation.
Large role in histamine release which causes constriction of large blood vessels, smooth muscle. Dilates venules. Histamine binds to 2 cell surface receptors, H1 and H2.
H1: Pro-inflammatory. In bronchi smooth muscle
H2: Anti-inflammatory. In gut patietal cells.
Big in allergies. Mast cell activation disorders seen as eczema, allergic conjunctivitis extreme example is anaphylactic reaction
Define: phagocytosis
Process by which cell ingests and disposes of foreign material via
1. adhere to bad guy
2. engulf
3. phagosome formation (makes a membrane surrounding engulfed particle )
4. fusion with lysosomal granules (pathogen is broken down into protein)
5. complete destruction of pathogen
Two significant phagocytes are NEUTROPHILS, MACROPHAGES
CELLS IN IMMUNE SYSTEM: Role of neutrophils?
Neutrophils, also known as polymorphonuclear neutrophils (PMNs)
First line of defense in innate immune response. Capture/destroy invaders via phagocytosis in addition to cleaning cellular debris, dead cells. SHORT LIVED. Dead neutrophils are in pus-filled drainage
CELLS IN IMMUNE SYSTEM: Role of monocytes and macrophages?
Monocytes: type of WBC. Made in bone marrow, circulate in blood 1-3 days then migrate to inflammatory site, develop into macrophage.
Macrophages: specialized in removing dead cells, debris. Kind of like professional phagocytes. Unlike monocytes, can live for months-years
2 phases of wound healing?
- Reconstructive
- Maturation
What are some causes of dysfunctional wound healing? What is the result?
B-cell vs T-cell, define both and state role
Both T and B lymphocytes are involved in adaptive immunity. Both made in bone marrow.
B-cells can transform into a) Plasmocytes (are responsible for producing antibodies).
b) Memory cells, allows for rapid immune response to a repeat foreign invader since is recognized.
T-cells mature in thymus (hence “T”).
a) T-helper cells activate B-cells via chemical messaging, thus initiating immune response.
b) Cytotoxic T-cells detect/destroy infected cells.
c) Memory T-cells remember invasion, help initiate fast response to identical invader.
**Humoral immune response deals with antigens, pathogen OUTSIDE cell, driven by B-cells via antibodies. Cellular immunity occurs INSIDE infected cells, driven by mature T-cells
