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MBBCh 2- PHSL2004A > 4. Immunology (1) > Flashcards

4. Immunology (1) Flashcards

1
Q

What is Immunology ?

A

The study of how the body defends itself against foreign organisms such as viruses, bacteria, parasites and fungi, as well as against foreign non-invasive cells, tissues, molecules.

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2
Q

What is a virus?

A

Small infectious agent that replicates only inside the living cells of other organisms.

  • Examples include:
    o influenza, common cold, coronavirus SARSov2 (COVID-19).
    o norovirus and rotavirus, common causes of viral gastroenteritis. o human immunodeficiency virus (HIV).
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3
Q
  • Humans and most other animals carry millions of bacteria. Most are in the gut, and there are many on the skin. Most of the bacteria in and on the body are harmless or rendered so by the protective effects of the immune system, and many are beneficial, particularly the ones in the gut.
  • However, several species are ________ and can cause disease.
  • The most common fatal bacterial diseases are _______ infections, for
    example tuberculosis and streptococcus pneumonia.
  • Antibiotics are used to treat bacterial infections.
A

pathogenic
respiratory

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4
Q
  • A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host.
  • 3 main classes of parasites that can cause disease in humans: ______, _______ and ______.
  • Of all parasitic diseases, malaria causes the most deaths globally.
  • Malaria is a ______-______ disease caused by any one of five malaria parasite species.
A

protozoa, helminths, and ectoparasites
mosquito-borne

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5
Q
  • There are millions of different fungal species on Earth, but only about _____ of those are known to make people sick.
  • Fungal diseases are often caused by fungi that are common in the environment. Fungi live outdoors in soil and on plants and trees as well as on many indoor surfaces and on human skin.
  • _______ = A common fungal skin infection that often looks like a circular rash.
  • ________ = candida is a type of yeast that normally lives in small amounts in places like your mouth, GIT and skin without causing any problems. But when the environment is right, the yeast can multiply and grow out of control.
A

300
Ringworm
Candidiasis

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6
Q

What is a pathogen? (4)

A
  • is any foreign organism (not a part of the body) that invades or is present inside the body.
  • can cause harm to the body and affects normal functioning.
  • can cause disease.
  • Examples would be bacteria, virus, fungi or parasites.
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7
Q

What is an antigen? (5)

A
  • antigen = antibody generator
  • is not an organism, but rather, a molecule attached to a foreign organism that activates an antibody response.
  • usually located in the cell walls of bacteria, or in the outer coating of other foreign organisms.
  • can also be an unusual peptide produced by a tumor cell.
  • may originate from within the body (“self-antigen”) or from the external environment (“non-self”).
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8
Q

Why is the immune system non-reactive against “self” antigens? (2)

A
  • The immune system is usually non-reactive against “self” antigens under normal homeostatic conditions due to negative selection of immune cells in the thymus and is supposed to identify and attack only “non-self” invaders from the outside world or modified/harmful substances present in the body under distressed conditions.
  • Negative selection deletes potentially self-reactive immune cells, thereby generating a repertoire of immune cells that is largely self-tolerant.
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9
Q

What are the physical barriers of protection? (7)

A
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10
Q
  • Infection occurs when viruses, bacteria, or other microbes enter your body and begin to ______.
  • In response to infection, your immune system springs into action.
  • Many of the _______ that make a person suffer during an infection—fever, malaise, headache, pain — result from the activities of the immune system trying to eliminate the infection from the body.
A

multiply
symptoms

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11
Q

What are the Jobs of the immune system? (9)

A
  • Communicate
  • Kill enemies
  • Cause inflammation
  • Activate other cells
  • Produce antibodies
  • Kill infected cells
  • Remember enemies
  • Mark/disable enemies I
  • Mark/disable enemies II
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12
Q

What are the cells of the immune system?

A
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13
Q

What are the features of monocytes and macrophages? (4)

A
  • Monocytes live for 1-3 days in blood
  • Macrophages live for a long time (months) in tissue
  • Phagocytes
  • Antigen presenting cells
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14
Q

How do monocytes and macrophages orchestrate immune responses?

A

Induce inflammation, secrete signaling proteins (cytokines) to activate lymphocytes and other phagocytes.

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15
Q

What are the features of dendritic cells? (4)

A
  • Live for days to weeks.
  • Phagocytes
  • Long finger like processes: ingest particles and extracellular fluid by macropinocytosis.
  • If they encounter a microorganism, they mature into cells capable of activating T lymphocytes = Antigen presenting cells
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16
Q

What are the features of neutrophils? (6)

A
  • Short-lived cells ~ 5 days
  • Phagocytes
  • Antigen-presenting cells to memory T helper cells.
  • Destroy microorganisms with granules (contain lysozyme & other degradative enzymes).
  • Release neutrophil extracellular traps (NETs).
  • Very effective at killing bacteria
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17
Q

What are the features of eosinophils? (4)

A
  • Involved mostly in defense against parasitic infections.
  • Secrete highly toxic proteins and free radicals that are highly effective in killing bacteria and parasites.
  • Phagocytes
  • Along with mast cells causes Inflammation and is involved in allergic responses.
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18
Q

What are the features of basophils? (7)

A
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19
Q

What are the main features of mast cells? (5)

A
  • Reside in tissue mainly near small blood vessels.
  • Function is similar and complementary to that of eosinophils and basophils.
  • Release histamine and heparin which are involved in inflammation.
  • Phagocytes
  • Are involved in allergic responses.
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20
Q
  • Each T-lymphocyte carries a different antigen receptor (T cell receptor) on its _______.
  • Selection of T cells with the correct T cell receptor happens in the _______.
A

surface
thymus

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21
Q

How is the T cell receptor from an immature T cell is tested against? (2)

A
  • The T cell receptor from an immature T cell is tested against major histocompatibility complex (MHC) from the self.
  • MHC is a group of genes that code for proteins found on the surfaces of cells that help the immune system recognize foreign substances.
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22
Q

What are the two major types of MHC protein molecules?

A

There are two major types of MHC protein molecules—class I and class II. Class I MHC molecules span the membrane of almost every cell in an organism, while class II molecules are restricted to cells of the immune system called antigen-presenting cells.

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23
Q
  • Immature T cells that recognize self-MHC and bind weakly to them receive signals for survival and will progress to become a ____ _____ T cell.
  • If the immature T cell doesn’t bind or if it binds too much with the self MHC then it is removed by _____ (a form of programmed cell death that occurs
    in multicellular organisms).
A

single positive
apoptosis

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24
Q
  • If the T cell receptor binds to an MHC class I-presented antigen then it is a _______________.
  • If the T cell receptor binds to an MHC class II-presented antigen then it is a ______________.
A

Killer/Cytotoxic T Cell (TC)
Helper T Cells (TH)

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25
Q

What are Killer/Cytotoxic T Cell (TC)?

A

Destruction of host cells infected with viruses or other intracellular pathogens

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26
Q

What are Helper T Cells (TH)?

A

Directs immune system by secreting cytokine

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27
Q

What are Memory T Cells (TM)?

A

Provide long–lasting immunity

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28
Q

What are Suppressor/Regulator T Cells (TS/R)?

A

Suppress activity of other lymphocytes to control immune responses

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29
Q

What are Suppressor/Regulator T Cells (TS/R)?

A

Suppress activity of other lymphocytes to control immune responses

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30
Q

How are B lymphocytes activated? (5)

A
  • Each B cell carries a different antigen receptor (B cell receptor) on its surface.
  • B cell receptor (BCR) is a surface antibody (or immunoglobulin)
  • When BCR binds to its antigen it activates the B lymphocyte
  • Activated B cells multiply and differentiate into plasma cells or memory cells.
  • Plasma cells produce antibodies
31
Q

What are the features of natural killer cells? (6)

A
  • Involved in the early phase of host defense to pathogen.
  • Have the capacity to recognize the surface changes that occur on a variety of
    tumor and virally infected cells.
  • Unlike killer T cells, they do not have antigen-specific receptors.
  • “Killing” method same as that of Killer T cells.
  • Release granules that kill some virus-infected cells by causing lysis of the infected cell. Lysis refers to the disintegration of a cell by disruption of its
    plasma membrane.
  • Secretes cytokines
32
Q

What is lymphoid tissue?

A

Lymphoid tissue = produce, store and process lymphocytes

33
Q

What is the function of primary/central lymphoid tissue?

A
  • Primary/Central lymphoid tissue sites are where lymphocytes mature into naïve cells in the absence of foreign antigen.
  • T Lymphocytes mature in the thymus.
34
Q

Bone marrow =

A

T + B Lymphocytes develop and B Lymphocytes mature.

35
Q

What is secondary/peripheral lymphoid tissue?

A
  • Secondary/Peripheral lymphoid tissue sites are where lymphocytes are exposed to foreign antigen, multiply and are activated.
36
Q

What are the causes of mononucleosis? (4)

A
37
Q

How is a lymph node processed? (4)

A
  1. Microbe is transported alone or in dendritic cell.
  2. Microbe is transported alone or in dendritic cell.
  3. Carries activated T and B lymphocytes and plasma B cells.
  4. Vein carries blood from the lymph node
38
Q

Type of lymphoid tissue: Bone marrow
Function: (2)

A
  1. Origin of all blood cells.
  2. Site of maturational processing of B lymphocytes.
39
Q

Type of lymphoid tissue: Lymph nodes, tonsil, adenoids, appendix, GALT
Function: (3)

A
  1. Exchange lymphocytes with the lymph (remove, store, produce and add them).
  2. Resident lymphocytes produce antibodies and activated cells, which are released into the lymph.
  3. Resident macrophages remove microbes and other particulate debris from the lymph.
40
Q

Type of lymphoid tissue: Spleen
Function: (3)

A
  1. Exchanges lymphocytes with the blood (removes, stores, produces and adds them).
  2. Resident lymphocytes produce antibodies and activated cells, which are released into the blood.
  3. Resident macrophages remove microbes and other particulate debris, most notably worn-out red blood cells, from the blood.
41
Q

Type of lymphoid tissue: Thymus
Function: (2)

A
  1. Site of maturational processing for T lymphocytes.
  2. Secretes the hormone thymosin (stimulates the development of T cells).
42
Q

What is innate immunity? (3)

A

Innate immunity: general protection against the ‘non-self’:
* Immediate defence against pathogens
* Does not confer long-term immunity
* Innate consists of cells and proteins that are always present and ready to
mobilize and fight microbes at the site of infection.

43
Q

What is adaptive immunity? (4)

A

Adaptive immunity (against specific pathogens, specific proteins that are recognized):
* Develops during the lifetime of an individual
* Takes a few days-weeks to develop
* Can create long-term immunity against a pathogen
* Adaptive immune system is called into action against pathogens that are able to evade or overcome innate immune defences.

44
Q

What is adaptive immunity? (4)

A

Adaptive immunity (against specific pathogens, specific proteins that are recognized):
* Develops during the lifetime of an individual
* Takes a few days-weeks to develop
* Can create long-term immunity against a pathogen
* Adaptive immune system is called into action against pathogens that are able to evade or overcome innate immune defences.

45
Q

Activation of the innate immune system
* Two pathways:

A

– Monocyte-macrophage pathway
– Complement system pathway
– These two pathways can coexist simultaneously

46
Q

Macrophages (tissue)/monocytes (blood) can exist in 3 stages of readiness:

A

Resting
Primed or activated
Hyperactivation

46
Q

Macrophages (tissue)/monocytes (blood) can exist in 3 stages of readiness:

A

Resting
Primed or activated
Hyperactivation

47
Q

What is the prime or activated stage of readiness in the monocyte-macrophage pathway?

A
  1. Interferon-gamma IFN-gamma
  2. Antigen presenting cell = Presenting antigen to activate T cells
  3. Major Histocompatibility Complex (MHC) Class II molecule
48
Q

What is the hyperactivation stage of readiness in the monocyte-macrophage pathway?

A
  1. Pattern recognition receptor alongside Interferon-gamma IFN-gamma
  2. “Hyperactivated” focused on killing. Tumor necrosis factor (TNF) :
    * Kills tumor cells
    * Kills virus infected cells
    * Activates other immune cells
  3. Increases the rate of phagocytosis
  4. Lysosomes which contain hydrolytic enzymes carry out their function
48
Q

What is the hyperactivation stage of readiness in the monocyte-macrophage pathway?

A
  1. Pattern recognition receptor alongside Interferon-gamma IFN-gamma
  2. “Hyperactivated” focused on killing. Tumor necrosis factor (TNF) :
    * Kills tumor cells
    * Kills virus infected cells
    * Activates other immune cells
  3. Increases the rate of phagocytosis
  4. Lysosomes which contain hydrolytic enzymes carry out their function
49
Q

What is ICAM and SLIG?

A
50
Q

What is SEL = selectin (receptor)?

A
  • Takes 6 hours to be produced and travel to the site of injury.
  • Adhesion partner for SLIG
51
Q

What are inflammatory signals?

A
52
Q

What is the function of histamine and bradykinin?

A
53
Q

How do Neutrophil extracellular traps (NETs) function? (5)

A
  1. Neutrophil is activated by cytokines or microbes
  2. Nucleus disintegrates (breaks up)
  3. Nuclear material mixes with content of granules (antimicrobial proteins)
  4. Plasma membrane ruptures
  5. Nuclear material + antimicrobial proteins released + neutrophil dies
54
Q
  • NK cells provide rapid responses to viral-infected cells and respond to tumor formation.
  • NK cells play 2 important roles in defending against pathogens:
A
  1. Lysis or apoptosis
  2. Release cytokines
55
Q

How do NK cells induce lysis or apoptosis? (5)

A
  1. Stress-induced molecule
  2. Activating receptor
  3. Granule with perforins and enzymes
  4. Perforin
  5. Apoptosis (programmed cell death) or osmotic cell lysis.
56
Q

How do NK cells induce the release of cytokines?

A
57
Q

What is the complement system?

A

The complement system refers to a series of more than 30 soluble, preformed proteins circulating in the blood and bathing the fluids surrounding tissues. The proteins circulate in an inactive form, but in response to the recognition of molecular components of a microorganism, they become sequentially activated, working in a cascade where in the binding of one protein promotes the binding of the next protein in the cascade.

58
Q

There are 3 complement pathways that make up the complement system:

A
  • the classical complement pathway,
  • the lectin pathway,
  • the alternative complement pathway.
59
Q

What are the functions of the alternative complement pathway? (3)

A
60
Q

What does the alternative complement pathway lead to?

A

Leads to the formation and activation of other complement proteins.

61
Q

Fill in the rest of the diagram.

A
62
Q

What is the function of C3b? (2)

A
  • C3b binds to either amino or hydroxyl groups.
  • Many of the proteins and carbohydrates that make up the surfaces of microorganisms have amino and hydroxyl groups.
63
Q

What is Opsonization?

A

Is the process by which a pathogen is marked for phagocytosis. Opsonization involves the binding of an opsonin, e.g., antibody or complement protein to proteins and polysaccharides (antigens) on pathogen surfaces; another portion attaches to receptors on phagocytes for enhanced phagocytosis.

64
Q

What is the function of Membrane attack complex (MAC)? (2)

A
  • The membrane attack complex (MAC) is a structure typically formed on the surface of pathogen cell membranes as a result of the activation of the host’s complement system.
  • The membrane-attack complex (MAC) forms transmembrane channels. These channels disrupt the cell membrane of target cells, leading to cell lysis and death.
65
Q

What does the lectin pathway lead to?

A

Leads to the formation and activation of other complement proteins.

66
Q

What is the protein that induces the lectin pathway?

A
66
Q

What is the protein that induces the lectin pathway?

A
67
Q

Fill in the rest of the diagram.

A
67
Q

Fill in the rest of the diagram.

A
68
Q

What are the visual signs of inflammation or inflection in the body? (2)

A
  • Pus forms: mix of live and dead neutrophils.
  • Swelling, oedema, redness and heat at inflammation site. Pain induced by local swelling.
69
Q

What are the physiological indicators of inflammation or inflection in the body?

A
  • ↑ neutrophils (above 10 000/mm3; 10 x 109 cells/L)
  • ↑ C-reactive protein (CRP) (NORMAL < 10 mg/l)
  • CRP is synthesized primarily in liver hepatocytes.
  • Pro-inflammatory cytokines released from immune cells such as
    macrophages stimulate the release of CRP.
  • ↑ Erythrocyte sedimentation rate
  • ↑ number of proteins circulating: plasma is more viscous, erythrocytes agglutinate together and form ‘rouleaux’. They ‘fall’ quicker in the tube and therefore accumulate at the bottom quicker.
70
Q

What is ESR?

A
  • ESR is the rate at which red blood cells precipitate in a period of 1 hour (in mm/hour)

MBBCh 2- PHSL2004A (19 decks)

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