Human Immune System Flashcards

1
Q

hematopoietic stem cells result in myeloid progenitor cells that give rise to _______________ immune cells (5)

A

neutrophils
eosinophils
basophils
dendritic cells
macrophages
mast cells

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2
Q

what role do neutrophils have?

A

they are the most abundant WBC

primary mediators of the rapid innate immune system vs bacterial and fungal pathogens

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3
Q

what does elevated neutrophils tell you?

A

most likely caused by infection or some sort of high stress – neutrophilia or neutrophilic leukocytosis

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4
Q

what role does eosinophils have?

A

specialized WBC (granulocyte; release highly toxic proteins and free radicals) for parasites and certain allergic diseases

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5
Q

what does elevated eosinophils tell you?

A

parasitic infection or certain allergic reactions like asthma, allergic rhinitis, and dermatitis

less common: certain blood cancers and eosinophilic granulomatosis with polyangitis

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6
Q

what role does basophils have?

A

least common WBC
granulocyte
involved in acute and chronic allergic diseases

can also play a role in parasitic infections

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7
Q

what does elevated basophils tell you?

A

infection, allergic disease attack, cancer like leukemia or an autoimmune disease

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8
Q

role of dendritic cells?

A

activate T cells and initiate adaptive immune response

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9
Q

role of macrophages?

A

phagocytosis, can activate T cells in the tissues

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10
Q

role of mast cells

A

release certain immune response mediators esp in response to bacteria, parasites, and allergies

ex. histamine, heparin, cytokines, and growth factors

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11
Q

in general, what is the lymphatic system?

A

its a network of vessels throughout the body that results in the movement of lymphatic fluids up towards two drainage points above the heart (subclavian veins)

lymph capillaries interact with blood capillaries so fluids from the tissues can be drained into the lymph

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12
Q

what is the role of lymph nodes and the spleen?

A

the police station for the adaptive immune system

place where B and T cells can hang out to wait to be activated by DCs and macrophages

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13
Q

what is the main role of the innate immune system?

A

first line defence; brings non-specified immune cells and inflammatory mediators to the site of invasion

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14
Q

is the innate immune system a fast or slow response?

A

fast, within minutes

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15
Q

how does the innate immune system recognize pathogens?

A

via PAMPs - pathogen-associated molecular patterns that are highly conserved components of pathogens for their virulence

the immune system has PPRs - pattern recognition receptors

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16
Q

what is the basic overview physiology of an innate immune response?

A
  1. effector cells recognize using PRRs via PAMPs
  2. triggers the complement system
  3. complement results in an increase in cytokines + vasodilation + increased vascular permeability
  4. also results in phagocytosis or MAC complex
  5. tissue becomes inflammed
17
Q

what is the role of the complement system?

A

it’s a mechanism to recruit and activate cellular immune responses that can participate in killing the pathogen

18
Q

name the three pathways to activate the complement system

A
  1. classical - antigen-antibody complex
  2. alternative - bacterial endotoxin
  3. lectin - specific glycoproteins
19
Q

what are complement proteins and where are they synthesized?

A

they are proteins involved in the complement system activation that are found in the blood, lymph, and ECF

most are produced in the liver and circulate in their inactive forms

20
Q

what are the end results of complement system activation?

A

there is a recruitment of inflammatory mediators, phagocytes and anaphylatoxins that increase vascular permeability

there is complement fixation ➔ opsonization ➔ enhances phagocytosis

finally, there is the formation of membrane attack complex (MAC) which forms a pore in the pathogen membrane which results in cell death

21
Q

what is the main role of the adaptive immune system?

A

it’s an antigen-specific response to a foreign antigen/pathogen that can be long lasting

consists of both cellular an humoral immunity

22
Q

what effector cells are most involved in the innate immune system?

A

leukocytes like neutrophils, eosinophils, basophils, DCs, macrophages, and mast cells

may also involved NK cells

23
Q

what effector cells are most involved in the adaptive immune system?

A

B cells and T cells (CD4 and CD8)

24
Q

what physical barriers could we also consider a part of the innate immune system? (3)

A

skin, saliva, mucous membranes

25
Q

what chemical barriers could we also consider a part of the innate immune system? (5)

A

urine pH, vaginal pH, stomach acid, tears, ROS

26
Q

what microbiological barriers could we also consider a part of the innate immune system? (3)

A

gut flora, vaginal flora, skin flora

27
Q

what physiologic barriers could we also consider a part of the innate immune system? (2)

A

cough reflex, fever - denatures proteins

28
Q

what are the two primary lymphoid organs? what are their functions?

A

bone marrow
thymus

both are where B and T cells mature into their naive forms until being released to the secondary lymphoid organs for activation

29
Q

what are secondary lymphoid organs?

A

Lymph nodes, spleen, peyer’s patches, and mucosal and nasal associated lymphoid tissues, adenoids, and tonsils

30
Q

what is the function of secondary lymphoid organs?

A

provide an environment for the proliferation and maturation of B and T cells in response to exposure whilst also filtering and trapping antigens from the hematogenous circulation

31
Q

how are naive T cells developed?

A
  1. common lymphoid progenitor cell in bone marrow
  2. becomes a T cell precursor in the thymus
  3. development of TCR via VDJ recombination
  4. maturation of T cells - positive selection (functional TCR) and negative selection (remove self-reactive TCR)
  5. naive CD4+ and CD8+ T cells developed and circulate in the lymphatic system until activation
32
Q

how are naive B cells developed?

A
  1. common lymphoid progenitor cell in bone marrow
  2. VDJ recombination to create BCR
  3. positive selection - functional BCR
  4. negative selection - self-tolerance mechanisms if self-reactive ➔ receptor editing, clonal deletion, or becoming anergic
  5. naive B cells circulate searching for infection
33
Q

how does cellular immunity work/happen?

A
  1. pathogen entry
  2. antigen-presenting cell ➔ MHC I on all nucleated cells ➔ activates CD8+ cytotoxic T cells
  3. direct pathogen killing
34
Q

how does humoral immunity work/happen?

A
  1. pathogen entry
  2. antigen-presenting cell ➔ directly to B cell receptor ➔ activate into plasma cell ➔ antibodies

OR MHCII on DC or macrophages ➔ activates CD4+ helper T cells ➔ activates B cells ➔ clonal expansion ➔ plasma cells ➔ antibodies
*can also activate cytotoxic CD8+ T cells

plasma cells become memory B cells

35
Q

what is the function of the spleen for the immune system?

A

white pulp - filtered blood ➔ allows for activation of B and T cells
- important for the detection and opsonization of encapsulated bacteria

red pulp - removal of damaged/old RBCs, acts as storage of RBCs and plts that can be used in cases of emergency

36
Q

what are 3 examples of encapsulated bacteria?

A

Streptococcus pneumoniae
Haemophilus influenzae
Neisseria meningiditis

37
Q

how do antibodies work in an infection?

A
  • neutralize the pathogen to prevent adhesion
  • opsonize the pathogen for macrophage
  • complement activation