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Microanatomy > Blood 2 > Flashcards

Blood 2 Flashcards

1
Q

how do neutrophils kill?

A

respiratory burst

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2
Q

what are the ROIs

A

suerpoxide anion, hydroxyl radical, hydrogen peroxide, hypochlorous acid

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3
Q

where does hypochlorus acid come from

A

from H2O2 by action of myeloperoxidase from azurophilic granules, produces hypochlorite (bleach)

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4
Q

what catalyzes the first step of the respiratory burst

A

NADPH oxidase

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5
Q

do phagosome membranes have NADPH oxidase

A

yes derived from plasma membrane

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6
Q

chronic granulomatous disease

A

involving any of the oxidase subunits
decreased or absent respiratory burst
recurrent bacterial and fungal infections
shorted life expectancy

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7
Q

specific granules contain

neutrophil

A

lysozyme: attacks cell walls of bacter, gram +
lactoferrin: competes with bacteria for iron and copper
collagenase: degrade ECM, easier access for neutrophil

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8
Q

azurophilic granules contain

neutrophil

A

myeloperoxidase: produces bleach
bactericidal/permeability-increasing protein (BPI): damages membranes of gram -
lysozyme
defensins: permeabilize bacterial membranes
neutrophil elastase: digest ECM

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9
Q

Chediak-Higashi syndrome

A

interferes with targeting of proteins to azurophilic granules, abnormally large vacuoles from fusion of azurophilic granules
don’t have mediators to kill bacteria

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10
Q

neutrophil extracellular traps (NETs)

A

strands of neutrophil chromatin with antimicrobial granule proteins
released from activated neutrophils
microbes stick and killed by high local concentrations of antimicrobial agents
help keep microbes from spreading
minimize local tissue damage
sepsis: NETs from within blood vessels
preeclampsia: form in intervillous spaces of placenta
require NADPH oxidase activity

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11
Q

how can neutrophils damage healthy tissue

A

elastase from azurophilic granules
collagenase from specific granules
release can occur during NET formation or phagocytosis
granules may fuse with phagosomes before it pinches off completely

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12
Q

what is pus and why is it green

A 
dead neutrophils (necrotic death)
green because of myeloperoxidase
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13
Q

how is pus removed

A

by macrophages

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14
Q

in what process are neutrophils important and what are 2 clinical indicators

A

important in acute inflammation

  • leukocytosis: increased number, release of greater than normal numbers of neutrophils from bone marrow
  • shift to the left: mature stores depleted, immature precursors released, shifts curve of nuetrophil age distribution
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15
Q

time course of an acute inflammation

A
  1. edema, leaky vessels by histamine
  2. neutrophils arrive during first wave, acute phase
  3. secrete chemotactic factors
  4. monocytes arrive, differentiate into macrophages, typical in late stage acute inflammation
  5. they phagocytize dead neutrophils, damaged tissue and other debris
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16
Q

extent of nuclear lobulation

neutrophil, eosinophil, basophil

A

neutro: 2-5 loves, thin strands
eosino: 2-3 lobes, thicker and/or shorter strands
baso: 2 poorly defined lobes

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17
Q

size and staining affinity of specific granules

neutro, eosino, baso

A

neutro: small, poorly staining
eosino: large, eosinophilic (pink to red)
baso: large basophilic (very dark purple)

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18
Q

specific granules of basophils

A

difficult to preserve, varied appearances
contents homogenous or grainy
may look like layers of membranes arranged in parallel stacks or whorls called myelin figures

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19
Q

basophil activation

A

involves IgE, made by plasma cells and binds to basophil receptors
primed but not activated
activated when exposed to antigen again and it binds to IgE causing it to cross-link

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20
Q

basophil activation leads to

A
  1. degranulation: mediators released are histamine and heparan sulfate, ECF and NCF
  2. cytokine synthesis and secretion: IL4 and IL3 promote class switching to IgE
  3. mediators from membrane phospholipids: LTC4 derived from arachidoic acid and PAF not from arachidonic acid
21
Q

major effects of basophil mediators

A
  1. vasodilation and increased permeability: histamine, haparan sulfate, PAF and LTC4
  2. bronchoconstriction: LTC4, PAF, histamine
  3. increased mucus secretion: histamine, LTC4
  4. class switching: cytokins IL4 and IL3
  5. chemotaxis of eosinophils, neutrophils, monocytes and macrophages: ECF, NCF, PAF
  6. itch (pruritis): histamine
22
Q

why is limited basophil activation beneficial?

A
  • vascular permeability makes it easier to reach tissues
  • increase mucus helps trap particulates
  • mild bronchoconstriction increases velocity of airflow
23
Q

why is excess basophil activation bad?

A
  • edema due to leaky vessels
  • excessive mucus secretion, nasal congestion
  • excessive bronchoconstriction, restricts airflow
24
Q

how can Type 1 hypersensitivity manifest

A

hay fever: nasal mucosa involved
asthma: bronchioles involved
hives (urticaria): skin involved
anaphylaxis: systemic rather than local, make unusually large amounts of IgE

25
Q

eosinophils lifecycle

A
  • IL5 stimulates their maturation
  • circulate 8-12 hours
  • leave vascular system by diapedesis, responding to histamine and eotaxins
  • lifespan can vary from a few days to around 18
  • greatest numbers in lamin propria of GI tract, except esophagus
  • eosinophilia associated with: infection with parasitic worms, allergy, asthma, eosinophilic gastrointestinal disorders
26
Q

eosinophils morphology

A
  • nucleus heterochromatic and bilobed
  • specific granules contain crystalloid embedded in amorphous matrix
  • they can have shiny appearance by LM
  • granules less eosinophilic at early stages
  • EM crystalloid may be lighter or darker than surrounding matrix
27
Q

eosinophil activation

A
  • can be activated experimentally by different stimuli
  • not clear what major in vivo activator is
  • one is analogous to IgE-mediated activation of basophils
  • eosinophil Fc receptors recognize IgG, IgA and secretory IgA
28
Q

what do activated eosinophils do?

A
  1. secreted stored mediators from specific granules by: exocytosis (fuse individually with plasma membrane) or piecemeal degranulation (small vesicles bud off and fuse with plasma membrane, specific granules remain intact, different stimuli trigger secretion of different subsets)
  2. respiratory burst that produces: superoxide, hydrogen peroxide, hypochlorite, hypobromite
  3. synthesize and secrete lipid mediators (LTC4, PAF) from lipid bodies formed soon after activation
29
Q

major eosinophilic functions

A
  1. kill larvae of certain parasitic worms, by secreting ROIs and mediators from specific granules: MBP (major component of crystalloid, reason for eosinophilia), ECP EDN, EPO (catalyzes formation of hypochlorite and hypobromite)
  2. phagocytize and destroy ag-ab complexes
  3. modulate basophil and mast cell activity: MBP activates them, can also destroy their mediators (arylsulfatase - LTC4, histaminase - histamine). Can have stimulatory or inhibitory effects
  4. antiviral activity against some ssRNA viruses via ECP and EDN RNAse activity
30
Q

Asthma

A 
eosinophils beneficial in parasitic infections and allergic reactions but can contribute to lung damage in chronic asthma
-mast cells are major effector in early attack
eosino involved in late phase 
-mediators can cause:
damage to ciliated cells
SM hypertrophy and hyperreactivity
bronchoconstriction
edema and leukocyte infiltration
increased fibrosis

eosinos may also be involved in increased numbers of goblet cells (hyperplasia) and increased mucus production

31
Q

monocyte morphology

A
  • wide size range, includes largest
  • irregularly shaped nuclues, not lobulated
  • lacy chromatin
  • nucleus and ctyo stain paler
  • cytoplasm is abundant
  • few azurophilic granules, no specific granules
  • large, pale vacuoles
  • well developed golgi, it produces azurophilic granules throughout monocyte lifespan

neutro have little golgi: cant produce azurophilic or specific granules, made only during differentiation

32
Q

monocytes can differentiate into

A

macrophages

  • they circulate in blood for a few days then enter tissues via diapedesis
  • differentiate in extravascular tissues
  • during inflammation rate of diapedesis increases greatly (make up wave of cells that arrives day after neutros at site of inflammation)
33
Q

morphology of histocytes

A

-greater phagocytic activity than monocytes
-more phagosomes, secondary lysosomes, plasma membrane pseudopods, etc
-presence of phagocytized material in cyto
-usually larger than monocytes
more irregular nucleus

34
Q

macrophage functions include

A
  1. phagocytosis: ordinary and removal of apoptotic cells, tissue debris, nuclei extruded from RBCs, old RBCs especially in spleen
  2. act as APCs: phagocytize and process antigen, partially degraded by lysosomal enzymes, bind to MHCII and presented to T helper cells
  3. secret products that promote:
    - inflammation: cytokines, IL1, IL6, IL12
    - hematopoiesis: CSF, GM-CSF
    - wound healing: growth factors, TGF-alpha
    - normal turnover of ECM: proteases such as elastase, collagenases
  4. wall off large particles or microorganisms: chronic inflammations, unable to eliminate
    - epithelioid cells: groups form resembling epithelium
    - giant cell: fuse together, multinucleated
35
Q

what is an important activator of macrophages

A

interferon gamma (IFN-gamma)

36
Q

macrophage-related cell populations

A 
osteoclasts in bone
microglia in CNS
aveolar macrophges (dust cells) in alveoli
kupffer cells in liver
langerhans cells in epidermis
histiocytes in connective tissue

ostoeclasts and histiocytes are bone marrow depenedent

others derive from precursors from yolk sac and/or fetal liver, maintained in postnatal life by mitosis

37
Q

small lymphocytes

A

> 90% of lymphocytes in blood

  • inactive in immune responses
  • nucleus kidney bean, highly heterochromatic
  • tin rim of basophilic cytoplasm
  • few azurophilic granules
  • no specific granules by LM or EM
  • few organelles by EM
38
Q

large lymphocytes

A
  • activated in an immune response
  • more euchromatic
  • smudged chromatic pattern
  • cytoplasm increases
  • also called immunoblasts or lymphoblasts
39
Q

lymphocyte activation results in

A
  • increase in size (blast transformation)
  • repeated mitosis to form clone cells
  • maturation of daughter cells into effector cells that carry out immune response or memory cells
40
Q

what are the three functionally different types of lymphocytes

A

T cells, B cells, NK cells

  • all arise from pluripotent hematopoietic stem cell in bone marrow
  • T and B cells cant be distinguished
  • NK cells have distinctive morphology
41
Q

T cells

A 
long life span
60-80%
TCRs that recognize and bind antigen in specific manner
essential for cell-mediated immunity
killing virus-infected and tumor cells
cannot be transferred passively

cytotoxic cells, helper T cells, regulator T cells, gamma/delta T cells

42
Q

T cytotoxic cells

A

-CD8+ surface marker
main effector cells
can kill target cells
killing requires close contact
killing mechanisms include secreting mediators such as
-perforin: help granzymes gain entry into cell
-granzymes: serine proteases whose activities include apoptosis

43
Q

T helper cells

A

CD4+ surface marker
recognize antigen on APCs such as macrophages, dendritic cell or B cell
secrete cytokines to help activate T cytotoxic cells and B cells
CD4 stabalizes interaction btw helper and APC

44
Q

HIV infection

A

CD4_ cells are infected and killed

binding of viral envelope protein to CD4 is first step that allows virus to gain entry into a cell

45
Q

regulatory T cells

A

down regulate immune resposnes

46
Q

gamma/delta cells

A

within epithelial layers
can constitute majority of intraepithelial lymphocytes
first line of defense against antigens that penetrate epithelial barrier

47
Q

B cells

A

humoral (antibody-mediated) immunity
can be transferred passively
plasma cells: effector cells derived from activated B cells
-secrete antibodies
-relatively short lived
-old plasma cells become russell body cells
large, distended RER cisternae, full of antibody and stain very eosinophilic

48
Q

NK cells

A

large granular lymphocytes (LGLs)
have azurophilic granules with perforin and granzymes
do not carry CD4, CD8 or B cell markers
5-10%
killing virus-infected cells and tumor cells
are not specific for one individual antigen
receptors that recognize range of inhibitory and simulatory ligands
-balance determins if NK cell will become activated and lyse target cell
-down-regulating ligands on target cells that inhibit NK cells or up-regulating ligands that stimulate it

-kill by variety of mechanisms including perforin and granzymes

Microanatomy (6 decks)

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