3 Microbiology: Innate and Adaptive Immunity Flashcards
0
Q
What is innate immunity?
A
Refers to the basic resistance to disease that an individual is born with.
1
Q
Immune response falls into what two categories?
A
Innate Immunity 1st (no memory- general) natural nonspecific
Adaptive Immunity 2nd (memory- specific)
2
Q
What is adaptive immunity?
A
the response of ANTIGEN-SPECIFIC LYMPHOCYTES to antigen, including the development of IMMUNOLOGICAL MEMORY
3
Q
Most micro organisms that encounter a healthy individual (or animal) are cleared in about how much time and by what kind of response?
A
usually cleared within a few days by INNATE defense mechanisms
4
Q
When invading microorganisms elude the innate host defense mechanisms and persist in host, what response is enlisted?
A
ADAPTIVE immune response
5
Q
What are the INNATE defense mechanisms?
A
epithelial barriers (i.e. skin)
Phagocytes
NKC (Natural Killer Cells)
6
Q
What are the ADAPTIVE defense mechanisms?
A
B Lymphocytes —> Antibodies
T Lymphocytes —> Effector T cells
7
Q
What provides the first line of defense against invading pathogens?
A
INNATE defense mechanisms
until an adaptive immune response develops
8
Q
What are three important factors about INNATE IMMUNITY? (true all the time)
A
Present in ALL individuals at ALL times
does not increase exposure to a given pathogen
does not discriminate between pathogens
9
Q
What are the components of INNATE IMMUNITY?
A
anatomic barriers (epithelial)
physiological barriers
inflammation
phagocytosis
10
Q
What are the body’s first line of defense against infection?
A
The skin and mucous membranes
results in both MECHANICAL and CHEMICAL FACTORS
11
Q
What is the skin composed of and describe them.
A
dermis (thick layer)
epidermis (thin layer) consists of several layers of tightly packed epithelial cells that prevent the penetration of most pathogens.
12
Q
What are two ways for pathogenic organisms to get past the skin?
A
breaks in the skin (even small ones)
penetration by biting arthropods (introduce pathogens as they feed if they are harboring pathogenic organisms)
13
Q
What are SEBACEOUS GLANDS?
A
they are associated with the hair follicles and produce an oily secretion called SEBUM
14
Q
What is SEBUM?
A
consists of LACTIC and FATTY ACIDS
maintains the pH of skin between 3 AND 5
15
Q
what is the pH that is inhibitory to the growth of most organisms?
A
between 3 and 5 (acidic)
16
Q
What do mucous membranes line?
A
gastrointestinal, respiratory, and genitourinary tracts
17
Q
What layers does the mucous membrane consist of?
A
epithelial layer and an underlying connective tissue layer
18
Q
mucous membranes provide what kind of protection compared to the skin?
A
LESS protection
19
Q
What are GOBLET cells?
A
cells in the epithelial layer of a mucous membrane that secrete a viscous fluid, mucus
20
Q
What does mucus do?
A
prevents the tracts from drying out
entraps foreign microorganisms that enter the respiratory and gastrointestinal tracts (?genitourinary tract {female}?)
21
Q
what covers the LOWER RESPIRATORY tract and why?
A
covered with CILIA (hairlike processes)
by moving synchronously, the cilia propel inhaled DUST and MICROORGANISMS that have become trapped in mucous, upward toward the throat to be swallowed (or coughed?)
22
Q
What is another mechanical factor that prevents microbial colonization in the GENITOURINARY tract?
A
cleansing the URETHRA by the flow of URINE
23
Q
What are NORMAL FLORA and what do they do?
A
they are nonpathogenic organisms that tend to colonize the epithelial cells of mucosal surfaces.
they generally outcompete pathogens for ATTACHMENT SITES on the epithelial cell surface and for necessary NUTRIENTS.
they may also secrete BACTERIOCINS that INHIBIT OR KILL INCOMING PATHOGENS. yay :)
24
What are the physiologic barriers that contribute to innate immunity?
temperature
pH
oxygen tension
various soluble factors (eg, complement proteins)
25
How does TEMPERATURE contribute to innate immunity?
many species are not susceptible to certain diseases due to the fact that their body temperature inhibits pathogen growth.
26
What causes a FEVER and what is its purpose?
The most frequent cause is infection from bacteria (and their toxins especially ENDOTOXIN) or viruses.
it inhibits the growth of some pathogens.
27
How does low pH (acidity) help protect the body from infections, and where does it come from?
Comes from gastric juices created by the stomach.
| the pH ranges from 1.2-3 and it destroys many viruses, bacteria and most bacterial toxins.
28
What is mixed in gastric juice?
hydrochloric acid
enzymes
mucus
29
What is one reason newborns are susceptible to some diseases that do not affect adults?
Their stomach contents are less acidic than that of adults
30
How can enteric pathogens enter the body?
They are protected by FOOD PARTICLES and MILK and can enter the intestines via the GI tract
31
How does OXYGEN TENSION protect the body?
Inhibits the growth of obligate anaerobes, especially in the lungs, where oxygen tension is very high
32
How does IRON-BINDING PROTEINS help protect the body?
proteins in the blood such as TRANSFERRINS, inhibit bacterial growth by reducing the amount of available iron.
33
How does too much iron affect the body?
It suppresses chemotaxis and phagocytosis.
It is needed by bacterial for the synthesis of CHYOCHROMES and certain ENZYMES therefore increases the risk of infection
34
What is the purpose of LYSOZYME and where are they found?
It cleaves the PEPTIDOGLYCAN LAYER of bacterial cell wall, rendering the bacterial cell susceptible to OSMOTIC LYSIS.
It is a HYDROLYTIC ENZYME found in MUCOUS SECRETIONS, TEARS, NASAL SECRETIONS, BLOOD, etc.
35
What does INTERFERONS do to cells?
It compromises a group of proteins produced by VIRUS-INFECTED CELLS.
They bind to neighboring cells and induce a generalized ANTIVIRAL STATE.
36
What is the COMPLEMENT SYSTEM?
is a group of blood proteins that circulate in an INACTIVE PROENZYME state.
These proteins can be activated by a variety of mechanisms that convert the INACTIVE PROENZYMES INTO ACTIVE ENZYMES.
Damage to membrane of pathogenic organism (LYSIS) or Facilitates PHAGOCYTOSIS (through chemotaxis)
37
The activated complement components participate in what?
In a controlled enzymatic cascade that results in damage to the membranes of pathogenic organisms, either destroying the pathogens or facilitating their clearance via phagocytosis.
38
What is the process INFLAMMATORY RESPONSE?
Tissue damage caused by a wound or by invasion by a pathogenic microorganism induces the sequence of events that concentrates the cells of the immune system and their products at the site of the injury or infection.
39
What are the four cardinal signs of inflammation?
```
redness (RUBOR)
heat (CALOR)
pain (DOLOR)
swelling (TUMOR)
loss of function (FUNCTIO LAESA) [added later in addition to the four]
```
40
What does the MICROVASCULATURE consist of?
the afferent arterioles
the capillary networks
the efferent venules
41
Where does the initiation of the inflammatory response mostly occur following tissue injury?
mostly at the level of the CAPILLARY and POSTCAPILLARY VENULES
42
The cardinal signs of acute inflammation reflect what three major events that occur at the level of the microvasculature during an inflammatory response?
Vasodilation
Capillary Permeability
Influx of phagocytes
43
What is VASODILATION and why does it occur?
It is an increase in the diameter of vessels.
This occurs because the blood vessels carrying the blood away from an affected area CONSTRICTS, resulting in engorgement of the capillary network.
44
Following vasodilation, what are the engorged capillaries responsible for?
They are responsible for TISSUE REDNESS (erythema) and an INCREASE IN TISSUE TEMPERATURE
45
What happens to CAPILLARY PERMEABILITY from an inflammatory response and why?
It is increased due to a retraction of the endothelial cells.
This allows PLASMA and PLASMA PROTEINS (soluble mediators of immunity) to reach the site of infection.
Accumulation of this exudate contributes to tissue swelling (EDEMA)
46
INFLUX OF PHAGOCYTES and other cells into the tissue is facilitated by what?
the INCREASED PERMEABILITY of CAPILLARY VENULES.
47
What happens in the earliest stages and later stages of inflammation regarding the influx of phagocytes?
Earliest stages- NEUTROPHILS are predominant
| later stages- MONOCYTES and LYMPHOCYTES also
48
Chemical mediators are from what sources?
derived from invading microorganisms.
released from damaged cells in response to tissue injury
generated by various plasma enzyme systems
products of various white blood cells
49
What is the principle mediator of the inflammatory response?
HISTAMINE
50
What is HISTAMINE and what does it do?
It is a chemical released by BASOPHILS and MAST CELLS in response to tissue injury.
It binds to receptors on nearby CAPILLARIES and VENULES, causing VASODILATION and INCREASED PERMEABILTY
51
What are other mediators of the inflammatory response?
prostaglandins
complement proteins
bradykinin
lipopolysaccharide (LPS)
52
Emigration of phagocytes is controlled by what, and why does this occur?
controlled by the ADHESION of the cells to the endothelial wall of the inflamed tissue (MARGINATION or PAVEMENTING).
This occurs because adhesion molecules on the surface of leukocytes interact with corresponding molecules on the activated endothelium
53
In the emigration of phagocytes, what follows after the adhesion of the cells to the endothelial wall?
followed by their emigration between the endothelial cells into the tissue (DIAPEDESIS or EXTRAVASATION)
54
What follows the emigration of phagocytes between the endothelial cells into the tissue?
The migration through the tissue to the site of the inflammatory response (CHEMOTAXIS)
55
What is CHEMOTAXIS?
Is the directional migration of cells UP CONCENTRATION GRADIENTS of chemotactic molecules.
56
In CHEMOTAXIS, what do the chemotactic agents do?
The agents diffuse from the site of inflammation to the adjoining VENULES, causing passing phagocytes to adhere to the endothelium.
57
In CHEMOTAXIS, what do the passing phagocytes do?
They insert pseudopodia between the endothelial cells and dissolve the basement membrane. They then pass out of the blood vessels and move up the concentration gradient of the chemotactic mediators in the direction of the site of inflammation.
58
What is PHAGOCYTOSIS?
Is the internalization of particulate matter such as bacteria, protozoa, fungi, etc. by "professional phagocytes" (neutrophils and macrophages)
59
What are the steps involved in PHAGOCYTOSIS?
Leukocyte adherence to vascular endothelium and extravasation.
Chemotaxis and membrane attachment.
Engulfment and ingestion of microorganisms.
Intracellular killing and digestion of microorganisms.
60
Neutrophils are the most abundant WBC in circulation of what species?
Humans and domestic animals EXCEPT pigs and cattle
61
In most species how long does it take for the bone marrow to produce a mature neutrophil?
In most species it takes 3 to 6 days
62
What are band neutrophils? What does it indicate if they are present in blood?
A neutrophil that is released from the bone marrow before it is mature (IMMATURE) and it will have a HORSEHOE NUCLEUS WITHOUT SEGMENTATION.
This indicates an increased demand for neutrophils beyond what the bone marrow can supply in mature neutrophils.
63
What do neutrophil granules (LYSOSOMES) contain?
contain DIGESTIVE ENZYMES that can destroy microorganisms that have been engulfed.
64
What is the average time a neutrophil spends in the circulation before it enters the tissue? How long does it stay in the tissue?
average of 4-8 hrs in circulation until it enters tissues.
once in tissues DOES NOT RETURN into circulation.
lives in tissues for 4-5 days.
65
In peripheral blood, what are the two pools that mature neutrophils are found?
the circulating pool
| the marginal pool
66
The CIRCULATING POOL of neutrophils is contained where?
contained in the blood as it flows through blood vessels. It is located in the lumen of vessel. Blood samples that are obtained for lab analysis contain neutrophils from this pool.
67
The MARGINAL POOL of neutrophils is composed of neutrophils from where?
composed of neutrophils that line the walls of small blood vessels.
These are NOT CIRCULATING and are not contained in blood samples obtained for lab analysis
68
The particular range of neutrophils is controlled by what factors?
Release of mature neutrophils from the storage pool in the bone marrow into the peripheral blood. (usually 5-DAY SUPPLY)
Rate of escape from peripheral blood into tissue. (rate depends on the need in tissue)
Increased production of neutrophils from PPSCs (usually 3-6 DAYS to mature)
69
What is NEUTROPHILIA?
INCREASE in the number of circulating neutrophils (LEUKOCYTOSIS)
70
What is NEUTROPENIA?
REDUCTION in the number of circulating neutrophils (LEUKOPENIA)
71
How do neutrophils bind to microorganisms?
may bind to microorganisms by way of their non-specific cell surface receptors.
Alternatively, if organism is OPSONIZED with a COMPLEMENT PROTEIN (C3b) and/or ANTIBODY (IgC), attachment will be through the neutrophil's MEMBRANE RECEPTORS for C3b and/or Fc portion of IcG.
It then extends pseudopodia around it which fuse and the microorganism is internalized (ENDOCYTOSED) in a membrane vesicle (PHAGOSOME)
72
What happens after there is a newly formed PHAGOSOME?
The newly formed phagosome fuses with the lysosomal granules of the neutrophil to form the PHAGOLYSOSOME.
This exposes the phagocytosed microorganisms to a barrage of enzymatically produced highly reactive molecules derived from the METABOLISM OF OXYGEN such as H2O2 (peroxide), SUPEROXIDE (O2), HYPOCHLORITE (HOCl), as well as to a concentrated mixture of LYSOSOMAL HYDROLASES, resulting in the digestion of the microbes. **PHAGOCYTOSIS**
73
What do neutrophils contain that chelates IRON and prevents some bacteria from obtaining this vital nutrient?
LACTOFERRIN
74
What are the largest WBCs in circulation and what is the percentage of them circulating in domestic animals?
MONOCYTES
| make up 5-6%
75
How are MONOCYTES different then NEUTROPHILS?
They mature faster in the bone marrow (within 24-36 hours)
They circulate in blood longer (10-20 hours)
When in tissues (as a macrophages) they are LONG-LIVED CELLS
76
Once monocytes LEAVE the bloodstream what happens to them?
Monocytes mature into MACROPHAGES. (which together with neutrophils are the main "professional phagocytes")
77
What is MONOCYTOSIS?
An INCREASED number of monocytes in peripheral blood.
| often associated with a CHRONIC INFLAMMATORY CONDITION, possibly an infection
78
What is MONOCYTOPENIA?
DECREASED number of monocytes in peripheral blood
79
What are the functions of MACROPHAGES?
They ingest foreign substances, including viruses, bacteria, protozoa, fungi, etc. (because they are larger than neutrophils they can engulf structures beyond the capacity of neutrophils such as dead neutrophils and senescent RBCs).
Clean up cellular debris that remain after inflammation or infection clears up.
process and present PROTEIN ANTIGENS to helper T CELLS.
secrete more than one hundred products, including CLOTTING FACTORS, COMPLEMENT PROTEINS, ANGIOGENESIS FACTOR, PROSTAGLANDINS, etc.
80
How much of the total WBC count is EOSINOPHILS, and how long does it take for them to mature?
5% or less of the total WBC count
| 2-6 days to mature in bone marrow
81
What is the half-life of EOSINOPHILS?
in tissues is 12 days
82
Where/what are sites of eosinophils, such as storage?
The bone marrow has a good reserve.
| there are circulating and marginal pools of eosinophils as well.
83
How long do EOSINOPHILS circulate in peripheral blood?
not very long, migrate into tissues in a few hours.
| They DO NOT reenter circulation once they leave blood vessels.
84
What is EOSINOPHILIA?
INCREASED numbers of eosinophils in peripheral blood.
| It is seen during ALLERGIC REACTIONS and certain PARASITIC INFECTIONS
85
WHat is EOSINOPENIA?
DECREASED numbers of eosinophils in peripheral blood.
86
What are the functions of EOSINOPHILS?
They have minimal phagocytic and bactericidal functions, (are not protective against most bacterial functions.)
They destroy some helminth parasites.
They modulate allergic inflammatory responses. (granules contain antiinflammatory enzymes that are released at the site of the allergic reaction.)
Secrete many pro-inflammatory mediators, including PLATELET-ACTIVATING FACTOR, LEUKOTRIENES, and PROSTAGLANDINS that contribute to VASODILATION, BRONCHOCONSTRICTION, and MUCUS PRODUCTION observed in anaphylactic reactions.
87
What is the least often seen WBC in circulation?
Basophils
| only 0.5%- 1% of leukocyte population
88
What are characteristics of BASOPHILS?
most often have a two- to three-lobed nucleus.
share some characteristics with TISSUE MAST CELLS.
granules contain HISTAMINE and HEPARIN.
89
What does HISTAMINE do?
helps initiate inflammatory reactions and acute ANAPHYLACTIC reactions (i.e. pollen allergy, penicillin allergy, ragweed, etc.)
90
What does HEPARIN do?
acts as a localized ANTICOAGULANT to keep blood flowing to an injured or damaged area.
91
Which LYMPHOCYTE is part of the INNATE immune response?
NKC Natural Killer Cells
92
In some species, NK cells appear as what?
LARGE GRANULAR LYMPHOCYTES (LGLs)
93
Why is NK Cell part of innate immune response and not adaptive?
An NK Cell LACKS AN ANTIGEN RECEPTOR that is typicl for either B or T cells, therefore it cannot be activated by a specific antigen.
94
What do NK Cells do?
kill some type of TUMOR CELLS and VIRUS-INFECTED CELLS.
