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HSC Biology > Module 7: Immunity > Flashcards

Module 7: Immunity Flashcards

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1
Q

What are the three lines of defence in the immune system?

A

Barriers to entry, the innate immune response, the adaptive immune response.

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2
Q

What are barriers to entry?

A

Structural and physiological adaptations that work to stop pathogens entering the body.

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3
Q

What is the innate immune response?

A

Non-specific mechanisms that try to destroy any pathogens that enter the body. This response is not improved with re-exposure to a pathogen.

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4
Q

What is the adaptive immune response?

A

Specific mechanisms that act to destroy a specific type of pathogen that has entered the body. This response is improved with re-exposure to the same pathogen.

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5
Q

What are the three types of barriers to entry?

A

External, internal, and chemical.

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6
Q

How does urination act as a barrier to entry?

A

During urination, muscle contractions and gravity help force urine down the urethra. The flow of urine flushes pathogens from the urethra, as they have trouble moving against the flow.

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7
Q

What are 5 innate antimicrobial molecules that aid in the destruction of pathogens?

A

IgA, lysozyme, mucus, defensins, enzymes.

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8
Q

What is IgA, and its role in the immune response?

A

It is present in present in tears, saliva, and mucous membranes, and aids the destruction of pathogens.

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9
Q

What are the two types of defensins?

A

Alpha defensins, and beta defensins.

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10
Q

What do beta defensins do?

A

Help epithelial surfaces to resist microbial colonisation. They can kill microbes by creating channels and disrupting the microbial cell membrane.

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11
Q

Where are alpha defensins found?

A

In macrophages, neutrophils, and intestinal paneth cells.

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12
Q

What does lysozyme do?

A

Has bactericidal properties; Present in sebum, perspiration, and urine. Paneth cells in the crypts of the small intestine produce lysozymes as well as phospholipase A and defensins.

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13
Q

Describe mucus as a chemical barrier to entry.

A

Has antiseptic peptides and works passively to prevent bacterial adhesion. The viscous nature of mucous traps bacteria, which can then be actively cleared by the mucociliary escalator in the lung or peristalsis of the gut. It is present in mucous membranes.

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14
Q

What are 2 examples of internal barriers to entry?

A

Mucous membranes and cilia.

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15
Q

Describe mucous membranes as a barrier to entry.

A

The digestive, respiratory, and genitourinary tracts are lined with these. They prevent microbes from entering tissues. The mucus they produce traps microbes and other particles.

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16
Q

Describe cilia as a barrier to entry.

A

Tiny, hair-like structures that help to move mucus upwards, plus any microbes or particles trapped in it.

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17
Q

Describe pH as a barrier to entry.

A

The acidity in the stomach and slightly alkaline conditions in the intestines kill many microbes. The skin’s acidity due to oils and sweat glands prevents the growth of many types of microbes.

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18
Q

Describe tears as a barrier to entry.

A

These liquid secretions in the body contain chemicals that harm microbes. For example, lysozyme enzymes, which break down bacterial cell walls.

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18
Q

Describe normal microflora as a barrier to entry.

A

These bacteria and fungi are not pathogenic. They are found on the skin, in the digestive tract and vagina, and on mucosal membranes. They reduce the ability of pathogens to access habitat and nutrients.

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19
Q

Describe fluid secretions as a barrier to entry.

A

Fluid secretions in the body contain chemicals that harm microbes. They contain chemicals that help to kill microbes.

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20
Q

Describe skin as a barrier to entry.

A

This provides an external barrier, strengthened by keratin proteins. It physically blocks the entry of microbial pathogens. It also regularly sheds outer layers, thus removing cells and pathogens.

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21
Q

What are defensins?

A

Defensins are small, cationic peptides with antimicrobial and antiviral properties, playing a crucial role in innate immunity.

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22
Q

What is an antigen?

A

Any particle that triggers the immune system to respond.

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23
Q

What are PAMPs?

A

Pathogen associated molecular patterns.

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24
How do pathogens act as antigens?
Pathogens act as they trigger the immune system because they have PAMPs and lack the “self” protein markers associated with host cells.
25
What do PAMPs include?
Carbohydrates, polypeptides, and nucleic acids found on the surface of pathogens that are common to a range of bacteria, viruses, and parasites.
26
What happens when pathogens enter the body?
They trigger both the innate and adaptive immune responses, which can occur simultaneously and can interact with one another.
27
What are the 4 aspects of the innate immune repsonse?
Phagocytosis, inflammation, secretion of antimicrobial proteins, and apoptosis.
28
What are phagocytes?
Phagocytes are immune cells, also called white blood cells, that engulf and digest foreign substances, pathogens, and dead cells.
29
What are the two types of phagocytes?
Neutrophils and macrophages.
30
What role do phagocytes play in the innate immune response?
A phagocyte is able to engulf microbes via endocytosis, then fuses with a lysosome allowing chemicals and enzymes to destroy the microbe.
31
What is the difference between neutrophils and macrophages?
Neutrophils are short-lived, primarily reside in the bloodstream, and are the first responders to infection. Macrophages, are long-lived, reside in tissues, and have a broader role in both innate and adaptive immunity.
32
What is an antigen presenting cell (APC)?
A phagocyte that displays fragments of the antigen on their surface after phagocytosis.
33
What role do APCs play in the innate immune response?
They help trigger other white blood cells (T cells) to begin a specific attack on that specific antigen.
34
What are the side effects of inflammation?
Localised redness, heat, and swelling.
35
What is the role of inflammation in the innate immune response?
Inflammation is a crucial part of the innate immune response, acting as a rapid defence mechanism against threats like pathogens and tissue damage. It involves a complex interplay of immune cells, blood vessels, and molecular mediators to eliminate the source of injury, clear damaged tissue, and initiate repair.
36
How does the inflammatory response occur?
Injuries to body tissue cause the release of chemicals (e.g. histamines and prostaglandins) that trigger an inflammatory response.
37
What is vasodilation?
Where nearby blood capillaries dilate and become more permeable.
38
What is it called when nearby blood capillaries dilate and become more permiable?
Vasodilation.
39
What is the benefit of vasodilation?
It allows blood components to exit the capillary and enter tissues. E.g. phagocytes will enter the tissue to help clear cellular debris and any microbes present.
40
What is swelling also known as?
Oedema.
41
What is oedema?
Swelling as part of the inflammatory response.
42
Describe the secretion of antimicrobial proteins as part of the innate immune response.
The innate immune response includes the secretion of many different proteins that aid defence. Some of these proteins directly attack antigens, while others help trigger further immune responses
43
What are lysosomes?
Lysosomes are enzymes in bodily fluids that directly attack bacterial antigens by breaking down their cell walls.
44
What is cell lysis?
The bursting of a cell, due to the variety of proteins present in the complement system.
45
What is interferon?
Interferon is an important antimicrobial protein that is involved in the immune response to viruses.
46
What is the role of interferon in the innate immune response?
Cells that have been infected by a virus release interferon, which can act beneficially on neighbouring cells, thus hindering viral replication in them.
47
What are NK cells?
Natural killer cells are a specialised type of white blood cell that can recognise body cells infected with viruses.
48
What do natural killer (NK) cells do?
They attach to infected cells and release chemicals that cause the infected cell to undergo apoptosis.
49
What is apoptosis?
The process of programmed cell death (cell suicide).
50
What is the adaptive immune system?
This system is antigen specific and goes into action after the host has already been exposed to that particular antigen before.
51
What feature do cells in the adaptive immune response have that is unique to this system?
Cells of the adaptive immune system have immunological memories, which means they actually ‘remember’ a pathogen from its previous attack and thus have built up a response against it the next time that particular pathogen enters the body.
52
What are lymphocytes?
Lymphocytes are a type of white blood cell crucial for the immune system's adaptive responses. They include T cells, B cells, and natural killer cells.
53
Where do T cells mature?
In the thymus of bone marrow.
54
Where do B cells mature?
In the bone marrow.
55
When are B and T cells activated?
When they bind to a specific antigen.
56
What are the 4 types of T cells?
Helper T cells, cytotoxic T cells, immunosuppressive T cells, memory T cells.
57
What do helper T cells do?
Coordinating the adaptive immune response. They activate other immune cells, like B cells and cytotoxic T cells, to fight infections. They do this by releasing signalling molecules called cytokines and by direct cell-to-cell interactions.
58
What do cytotoxic T cells do?
Use chemicals to kill any antigen-presenting cells.
59
What do immunosuppressive T cells do?
Inhibit immune cells at the end of an immune response.
60
What do memory T cells do?
Allow a more effective response if re-exposure occurs.
61
What are the 2 main types of B cells?
Plasma B cells and memory B cells.
62
What do plasma B cells do?
Produce many antigen-specific antibodies.
63
What do memory B cells do?
Responsible for long-term immunity against specific pathogens. They are specialised B cells that remember previous encounters with antigens and are primed to rapidly respond to future infections with the same antigen.
64
What are antibodies?
A blood protein produced in response to and counteracting a specific antigen. Antibodies combine chemically with substances which the body recognises as foreign, such as bacteria, viruses, and foreign substances in the blood.
65
What is humoral immunity?
The immune response involving B cells and their antibodies, which can extend to extracellular antibodies.
66
What type of response are B cells involved in?
Humoral immune response.
67
What type of response are T cells involved in?
Cell-mediated immune response.
68
What is cell-mediated immunity?
Cell-mediated immunity is a type of adaptive immunity that relies on the action of immune cells, particularly T lymphocytes (T cells), to directly target and destroy infected or cancerous cells, rather than relying on antibodies like humoral immunity
69
What part of a plasma B cell produces antibodies?
Ribosomes.
70
Why is the secondary immune response faster and with greater antibody production?
Memory B and T cells are formed following a primary exposure to an antigen. These memory B and T cells recognise an antigen upon re-exposure, thus allowing a more rapid, stronger response.
71
What type of cell releases antibodies?
Plasma B cells.
72
What types of cells do activated B cells form?
Plasma B cells and memory B cells.
73
Why would a memory B cell become activated?
Re-exposure to the same antigen.
74
Why do cytotoxic T cells fight against viral infections better than plasma B cells.
Viruses need to invade cells in order to replicate, and plasma B cells can only respond to extracellular antigens. However, cytotoxic T cells can recognise and kill cells that have been invaded by viruses.
75
What are the 4 steps involved with helper T cells?
(1) Helper T cell binds antigen-presenting cell. (2) Both cells release chemicals called cytokines. (3) Cytokines help stimulate the helper T cell to clone itself. (4) The cloned T cells produce different cytokines that activate B cells and cytotoxic T cells.
76
What type of cell initially stimulates a helper T cell?
Antigen presenting cell (APC).
77
What innate immune cells can form APCs?
Phagocytes.
78
What are the 4 steps involved with cytotoxic T cells?
(1) Cytotoxic T cell detects an infected cell and releases perforins and granzymes. (2) Perforins create pores in the cell membrane. Granzymes then enter the cell and break down proteins. (3) The damage to the infected cell causes it to die via apoptosis.
79
What are the 2 types of chemicals released by cytotoxic T cells?
Granzymes and perforins.
80
What role do granzymes play in the cell-mediated immune response?
They enter the pores in a cell created by perforins and break down proteins.
81
What role do perforins play in the cell-mediated immune response?
Create pores in an infected cell's membrane.
82
What triggers apoptosis in the cell-mediated immune response?
Damage from the perforins and granzymes.
83
How do helper T cells assist cytotoxic T cells?
Helper T cells produce cytokines that are needed to activate cytotoxic T cells.
84
Why does an injury site become red and swollen?
The inflammatory response has occurred, with increased blood flow and white blood cells entering the tissue.
85
What are cytokines?
Any of a number of substances, such as interferon, interleukin, and growth factors, which are secreted by certain cells of the immune system and have an effect on other cells.
86
What role do cytokines play in the immune system?
Cytokines are crucial signalling molecules in the immune system, acting as messengers that regulate immune responses. They control the growth and activity of immune cells and other cells involved in inflammation.

HSC Biology (11 decks)

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