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microbiology Flashcards

1

1
Q

What is the function of the epithelial barrier in the immune system?

A

Harbors harmless commensal microorganisms, collectively called the microbiome, that inhabit distinct niches.

The microbiome competes for nutrients and evolves antimicrobial strategies to coexist and defend the niche.

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2
Q

What is the role of innate immune cells?

A

They respond when the barrier has been breached, acting as the second line of defense, with phagocytes being the most important cells.

Phagocytes are crucial for detecting and eliminating foreign material and debris.

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3
Q

What are macrophages?

A

Tissue macrophages reside in normal tissue and are the first cells to encounter foreign material.

They play a critical role in initiating the immune response.

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4
Q

What is the function of neutrophils in the immune response?

A

They migrate into damaged tissue and contribute to inflammation.

Neutrophils are often among the first responders to sites of infection.

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5
Q

What is the role of dendritic cells?

A

They carry away microbial material to nearby lymphoid tissues, where they activate the adaptive immune response.

Dendritic cells are key in linking innate and adaptive immunity.

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6
Q

Fill in the blank: The first step of an immune response is that innate immune cells recognize _______ material.

A

foreign

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7
Q

What components of the innate immune arm detect foreign material?

A

Certain carbohydrates or lipids on the surface of microorganisms (LPS).

These components are crucial for the recognition of pathogens.

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8
Q

What are pattern recognition receptors (PRRs)?

A

Receptors that recognize a molecular pattern called a pathogen-associated molecular pattern (PAMP) present on the surface of many microbes.

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9
Q

True or False: Innate immune cells need a highly specific receptor for each individual microbe strain.

A

False

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10
Q

What are Toll-like receptors (TLRs)?

A

Extracellular pattern recognition receptors that play a significant role in the innate immune response.

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11
Q

What are NOD-like receptors (NLRs)?

A

Intracellular pattern recognition receptors involved in detecting pathogens.

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12
Q

What happens if there are mutations in the genes encoding pattern recognition receptors?

A

They result in a failure to recognize pathogens and predispose to severe bacterial, viral, and fungal infections.

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13
Q

What occurs after recognition of a pathogen by innate immunity?

A

Innate immunity is activated to increase production of pro-inflammatory signals that have three key effects:
* To kill invaders and recruit other immune cells to the area
* To block the infection from causing disease beyond the local site of inflammation
* To aid in repairing the damaged barrier.

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14
Q

What types of cells exert the functions of the innate immune response?

A

Antigen-presenting cells (APCs), granulocytes, and innate lymphocytes called NK cells.

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15
Q

What is immunology?

A

The study of the immune system or immunity.

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16
Q

What is immunology?

A

The study of immune system or immunity.

It encompasses all aspects of host defense against infection.

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17
Q

What are antigen presenting cells (APCs)?

A

Monocytes and macrophages that present antigens to T cells.

The most abundant professional APCs are myeloid cells called macrophages.

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18
Q

What are the three main functions of tissue-resident macrophages and monocyte-derived macrophages?

A
  • Phagocytosis
  • Antigen presentation
  • Cytokine production
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19
Q

What is phagocytosis?

A

The process by which macrophages, neutrophils, and dendritic cells ingest bacteria, viruses, and foreign particles.

Phagocytes have receptors for C3b and immunoglobulins that enhance the uptake of microbes.

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20
Q

What are opsonins?

A

Factors such as complement and immunoglobulins that bind to microbes and enhance phagocytosis.

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21
Q

What happens after ingestion of a microbe by a phagocyte?

A

The phagosome containing the microbe fuses with a lysosome.

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22
Q

What occurs during antigen presentation?

A

Fragments of antigen are presented on the macrophage cell surface in conjunction with class II MHC proteins.

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23
Q

What stops the degradation of foreign proteins during antigen presentation?

A

When the fragment associates with the MHC protein in the cytoplasm.

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24
Q

What are the major cytokines produced by macrophages?

A
  • Interleukin (IL)-1
  • IL-6
  • Tumor necrosis factor-alpha (TNF-alpha)
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25
What role do dendritic cells play in the immune system?
They are main inducers of the primary adaptive immune response and serve as a bridge between innate and adaptive immunity.
26
Where are dendritic cells primarily located?
In barrier tissues, including the skin and the mucosa of the gastrointestinal, respiratory, and genitourinary tracts.
27
What is the significance of neutrophils in innate host defenses?
They are important components, and severe infections can occur if they are too few or deficient in function.
28
How do neutrophils assist in phagocytosis?
They have surface receptors for IgG, which facilitates the phagocytosis of opsonized microbes.
29
True or False: Neutrophils display class II MHC proteins on their surface.
False.
30
Fill in the blank: The physiological mechanisms that enable the body to recognize materials as foreign and to eliminate them is the study of _______.
Immunology.
31
What do granulocytes like eosinophils do in response to parasitic diseases?
The eosinophil count is elevated in parasitic diseases, especially those caused by tissue invading nematodes and trematodes, and hypersensitivity diseases such as asthma. ## Footnote Eosinophils play a critical role in the immune response to parasites.
32
Do eosinophils present antigens to helper T cells?
No, eosinophils do not present antigen to helper T cells. ## Footnote This is in contrast to macrophages, which are both phagocytes and antigen-presenting cells (APCs).
33
What cytokine stimulates the growth and differentiation of eosinophils?
Interleukin-5 (IL-5) stimulates the growth and differentiation of eosinophils. ## Footnote Eotaxin is a chemokine that attracts eosinophils from the blood into tissues.
34
Where do basophils circulate compared to mast cells?
Basophils circulate in the bloodstream, while mast cells are fixed in tissues, especially under the skin and in the mucosa of the respiratory and gastrointestinal tracts. ## Footnote Mast cells are similar to basophils in many ways.
35
What receptors do basophils and mast cells have?
Basophils and mast cells have receptors on the cell surface for the Fc portion of the heavy chain of IgE. ## Footnote This allows them to mediate allergic responses.
36
What do natural killer (NK) cells do?
NK cells kill virus-infected cells and tumor cells and produce IFN-γ that activates macrophages to kill bacteria. ## Footnote NK cells are considered 'natural' because they do not recognize their target cells by detecting antigens.
37
How do NK cells kill target cells?
NK cells kill virus-infected and tumor cells by secreting cytotoxins (perforins and granzymes). ## Footnote These cytotoxins induce apoptosis in target cells.
38
What are the classic symptoms of local inflammation?
The classic symptoms of local inflammation are pain, redness, warmth, and swelling. ## Footnote These symptoms arise as an effort to recruit leukocytes to the area and limit the spread of infection.
39
What are some innate signals of tissue damage?
Innate signals of tissue damage include lipid mediators (e.g., prostaglandins and leukotrienes), histamine, activated complement, and components of the coagulation cascade. ## Footnote These signals lead to redness, warmth, and swelling through vasodilation and vascular leak.
40
What role does nitric oxide (NO) play in inflammation?
Nitric oxide is produced by macrophages and neutrophils and causes vasodilation, contributing to hypotension seen in septic shock. ## Footnote NO is a crucial mediator in the inflammatory response.
41
What causes the release of bradykinin, and what effects does it have?
Bradykinin causes vasodilation, vascular leak, and pain. ## Footnote It is involved in the inflammatory response and can amplify pain signaling.
42
What are cytokines used for in the immune system?
Immune cells use cytokines to communicate with each other and with other cells of their environment. ## Footnote Cytokines are critical for coordinating immune responses.
43
Can cytokines be produced by various cell types?
Yes, cytokines can be produced and sensed by numerous cell types in different locations. ## Footnote This versatility allows for a broad range of immune responses.
44
What are cytokines?
Cytokines are signaling molecules produced and sensed by numerous cell types in different locations.
45
What are chemokines?
A group of cytokines that attract leukocytes and help them migrate to where they are needed.
46
What role do chemokines play in leukocyte movement?
Chemokines bind to selectins on the endothelial cell surface, enabling leukocytes to roll and migrate.
47
What is the approximate number of identified chemokines?
Approximately 50 chemokines have been identified.
48
Which cells do alpha-chemokines generally attract?
* Neutrophils * Monocytes * Dendritic cells * NK cells
49
What is the role of beta-chemokines?
Beta-chemokines attract macrophages and monocytes and are produced by activated T cells.
50
What is the acute-phase response?
A rapid, systemic increase in various plasma proteins in response to innate inflammation.
51
What are common symptoms of the acute-phase response?
* Fever * Malaise * Elevated heart rate * Loss of appetite
52
What cytokines are produced by macrophages in response to IL-1?
* IL-6 * TNF-a
53
What characterizes adaptive immunity?
Occurs after exposure to an agent, improves upon repeated exposure, and is specific.
54
What cells mediate adaptive immunity?
* B lymphocytes * T lymphocytes
55
What is the ratio of T cells to B cells in the adaptive immune system?
Approximately 3:1.
56
What are the two main functions of B cells?
* Differentiate into plasma cells that produce antibodies * Become long-lived memory B cells for rapid response to reinfection
57
What are antibodies made of?
Glycoproteins made up of light and heavy polypeptide chains.
58
What is the antigen-binding fragment of an antibody called?
Fab
59
How many classes of antibodies are there?
* IgM * IgD * IgG * IgE * IgA
60
What is the role of CD4+ T lymphocytes?
They help B lymphocytes produce antibodies and assist phagocytes in destroying ingested microbes.
61
What is the function of regulatory T lymphocytes?
They prevent or limit immune responses.
62
What do effector CD4+ T cells produce?
Cytokines that activate B cells, macrophages, and other cell types.
63
What distinguishes CD8+ T lymphocytes?
They are cytotoxic and capable of suppressing other T cell responses.
64
How do CD8+ T lymphocytes perform cytotoxic activities?
They are first converted to effector cytotoxic T lymphocytes.
65
What are CD8+ T lymphocytes converted into for cytotoxic activities?
Effector cytotoxic (CTL) lymphocytes ## Footnote Converted by IL-2 and IFN-γ.
66
What type of immunity is present at birth and does not require prior exposure to microbes?
Innate immunity ## Footnote Characterized as nonspecific.
67
What are the primary functions of innate immunity?
Host defenses such as barriers to infectious agents and clearing away dead cells ## Footnote Includes skin, mucous membranes, macrophages, NK cells, and complement.
68
What is the difference between innate and adaptive immunity regarding memory?
Innate immunity has no memory, while adaptive immunity has long-term memory.
69
Name the primary lymphoid organs.
* Bone marrow * Thymus
70
What is the role of bone marrow in the immune system?
Maturation site of B lymphocytes, NK cells, and myeloid lineage cells.
71
What is the role of the thymus in the immune system?
Maturation site of T lymphocytes ## Footnote It is the only lymphoid organ without antibody synthesis.
72
List the secondary lymphoid organs.
* Spleen * Lymph nodes * MALT (Mucosa-associated lymphoid tissue)
73
What are the components of the innate immune system?
* Mechanical barriers * Chemical barriers * Biological barriers
74
What is an example of a mechanical barrier in the innate immune system?
Skin and epithelial cells ## Footnote Sweat secretion limits microorganism attachment.
75
What is an example of a chemical barrier in the innate immune system?
Epithelial cells produce chemicals that inhibit microbes ## Footnote Includes hydrochloric acid in the stomach.
76
What is lysozyme and where is it found?
An enzyme in saliva and tears that breaks down bacterial cell walls.
77
Fill in the blank: Innate immunity responds _______ and targets molecular patterns that are widely shared among microbes.
rapidly
78
What are antimicrobial peptides such as defensins produced by?
Produced throughout the skin and mucous membranes ## Footnote Create pores in the lipid membranes of bacteria, fungi, and some viruses.

microbiology introduction (1 decks)

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