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Histology > CT blood > Flashcards

CT blood Flashcards

1
Q

General functions of blood (8):

A
  1. Nutrient transport
  2. Gas transport (O2/CO2)
  3. Waste transport (urea)
  4. Hormone transport
  5. control of pH /electrolytes
  6. defense against pathogens
  7. thermoregulation
  8. reduces the loss of fluid through injuries (coagulation)
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2
Q

How can blood be separated?

A
  1. treating blood with anticoagulation factors, to prevent thrombus formation during separation
  2. Centrifugation and sedimentation
  3. Separation into the three layers of blood
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3
Q

Regulation of pH and consequences of deviation

A
  • blood pH maintained at around 7.4

-ACIDOTIC COMA: if the pH falls below 7 (drowsiness due to shortage of O2)

-ALKALOSIS TETANY: if the pH rises above 7.8 (can cause muscle spasms)

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4
Q

What is the difference between plasma and serum?

A

PLASMA: liquid, cell free portion of blood that has been treated with anticoagulants

SERUM: liquid portion of blood AFTER coagulation, and is hence devoid of fibrinogen

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5
Q

What are the components of the 3 layers blood is separated into?

A
  1. TOP LAYER = PLASMA: liquid, straw-coloured ECM portion (55%)
  2. MIDDLE LAYER = BUFFY COAT: leukocytes and platelets (<1%)
  3. BOTTOM LAYER = ERYTHROCYTES: RBCs (44%)
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6
Q

Hematocrit def and use in diagnosing

A

Hematocrit: volume occupied by erythrocytes in relation to total volume of blood

Usual values between 30-50% (lower in women)

ANEMIA: pathology associated with low hematocrit, causing anoxia

POLYCTHEMIA: pathology associated with high hematocrit, slow growing bone cancer

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7
Q

Erythrocyte sedimentation rate def and use in diagnosis

A

ESR: Measure of hoq quickly RBCs fall to the bottom of a tube when left for one hour at RTP

High ESR: pathologies associated with over coagulation, since it shows the blood is thicker/ heavier which is caused by clumping and aggregation of RBCs

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8
Q

Blood lipemia definition

A

-presence of lipemic serum, which is milkier than normal plasma.
-leads to the accummulation of lipids in the blood plasma

!! this is an indication of the patient not fasting significantly long before blood test

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9
Q

Components of the blood plasma

A

92% Water, 7% proteins and 1% other solutes

PROTEINS PRESENT:

  1. Albumin: controls osmotic pressure by exerting conc gradient between blood and extracellular tissue fluid.
    !! leaking of albumin causes swelling due to decreased osmotic pressure + accummulation of fluid in tissues
  2. Globulins:
    -non immune (alpha/beta): carrier proteins for substances (eg. Cu/Fe/Hb/lipids)
    -immune (gamma): antibodies for immune response
  3. Fibrinogen/coagulation proteins: soluble fibrinogen is changed into insoluble fibrin to form the mesh needed for platelet clumping
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10
Q

Where does the production of plasma proteins occur?

A

in the liver (except gamma globulins which are produced by plasma cells)

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11
Q

Blood smear procedure and use in diagnosis

A

PROCEDURE: collect small drop of peripheral blood, place on slide and smear with another slide. Obtain a thin film which is left to dry. Apply staining (usually Giemsa stain) and visualise cells under microscopy

AIM: Ensure normal morphology of cells (alterations in morphology can cause pathologies)

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12
Q

How can blood plasma proteins be separated and why is this used?

A

SERUM PROTEIN ELECTROPHORESIS: separates proteins and gives a graph with peaks associated to the concentration of each protein

AIM: to identify whether the concentration of each protein is in the norma range, as alterations can cause pathologies

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13
Q

What techniques are used to find concentration of blood cells?

A
  1. MANUAL COUNTING: a drop of blood is diluted with isotonic solution (so there is no disruption of membrane) and cells are placed in a haemocytometer grid to be manually counted
  2. AUTOMATIC COUNTING: electronic blood cell counter used (cytofluometry). Identifies antigens on each cell and so shows conc of each cell type.
    ! Dimension/density of cells are also used as identifiers of cell type
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14
Q

Leukocyte formula definition

A

The percentage of each of the 5 types of leukocytes present in the blood

!! also called differential leukocyte count

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15
Q

Morphology of erythrocytes

A

-BICONCAVE (maintained by membrane proteins): diameter in the center is smaller than on the sides which allows Hb to get closer to plasma membrane and have a shorter diffusion distance for oxygen

-anucleated and no organelles
-filled with Hb
-flexible to squeeze through capillaries
-120 day lifespan
-membrane contains integral and peripheral glycoproteins
-produced in red bone marrow

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16
Q

Erythrocyte roleaux definition

A

-clumps/aggregates of red blood cells that appear like a stack of coins
-form due to increase in immunoglobulins
-indicative of a pathology but are NOT specific

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17
Q

Composition of RBC plasma membrane + detailed proteins

A
  1. INTEGRAL PROTEINS:

-2 families: GLYCOPHORINS and BAND 3 proteins
- extracellular domains are glycosylated (determines blood type)

  1. PERIPHERAL PROTEINS:

-found intracellularly
-SPECTRIN alpha and beta run parallel to cell membrane –> can be remodelled to alter cell shape and allow flexibity. Connect membrane and cytoskeletal elements.

2 protein complexes that anchor spectrin to bilayer:

ADDUCIN/4.1 PROTEIN complex: bind to intracellular compartments of band 3 proteins

ANKYRIN/4.2 PROTEIN complex: bind to spectrin and intracellular compartment of p55 protein

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18
Q

What is the general life cycle of a red blood cell?

A
  1. Hematopoiesis in bone marrow
  2. Reticulocyte release into blood
  3. Differentiation into mature RBC
  4. Death and degradation by phagcytosis
  5. Recycling of cell components by te organism (like Hb)
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19
Q

What consequence could a mutation in RBC membrane proteins have?

A

Mutations to peripheral proteins like spectrin could sever the connection between the membrane and the cytoskeletal elements

CONSEQUENCE: RBC shape changes to spherical, and flexibility is lost

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20
Q

Components of RBC cytoplasm

A

-H2O(66%) and proteins (33%)

-major protein is Hb: tetrameric containing 4 haem groups, hence can bind to 4 O atoms (binding of O2 is revesible)

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21
Q

What are the changes to Hb as a human ages?

A

-changes in the isoforms of Hb, meaning changes in the chains its composed of:

  1. Fetal Hb: 2a, 2c
  2. Adult HbA: many isoforms but the most abundant one is 2a 2b
  3. Adult HbA2: present less then 3% of total Hb, and contains 2a 2d
22
Q

2 pathologies associated with defects in Hb

A
  1. SICKLE CELL
    -mutation of beta chain of Hb which alters structure (forming Hb-S)
    -causes polymerisation into aggregates which changes the cell shape into a spindle.
    -less flexibilty causes anemia and anoxia
  2. Hb H DISEASE:
    -mutation in alpha chain of Hb. Characterised by the existence of adult Hb that contains 4beta chains
    -causes hemolytic anemia with high reticulocyte counts
23
Q

Reticulocytes def and morphology

A

-RBC precursors (immature) signifying the last step of erythrocyte maturation
-released into blood by bone marrow
-diferentiate into RBCs by losing ribosomes
-present 0.5-2% volume in blood

!! DIFFERENT TO RBCS: they posess attached ribosomes which are not present on RBCs. Hence they can be visualised using ribosome specific stains

24
Q

What is the use of blood reticulocyte count in diagnosis?

A

High RLC count: diagnoses hemolytic/post-hemoraghic anemia

Low RLC count: diagnoses hypoproliferative anemia (erythrocyte progenitor dysfunction)

25
Q

Main characteristics of platelets

A

-fragments of megakaryocyte (MK) cytoplasm in the bone marrow
-anucleated
-contain basophilic granules in cytoplasm
-receptors present on membrane
-disc shape (become spherical when activated)
-partake in clotting cascade for thrombus formation
-lifespan of 8-10 days
-contain 4 anatomical regions

26
Q

Process of platelet formation (7 steps) and subsequent life cycle

A
  1. MKs undergo endomitosis (which is driven by TPO - thrombopoetin)
  2. MK maturation and formation of invaginations
  3. Creation of demarcation membrane systems (canals made of flattened cisternae)
  4. This causes complete partitioning of cytoplasmic fragments forming platelets
  5. Migration of MKs to endothelial cells of bone marrow sinusoids
  6. Extension of long pseudopodal protrusions (called proplatelets) into bone marrow
  7. Release of platelets from their ends
  8. Remain in blood circulation for 8-10 days
  9. Removed by the liver (by kupffer cell macrophages)
27
Q

What are the components of the 4 anatomical platelet zones?

A
  1. PERIPHERAL ZONE: membrane and glycocalyx
  2. STRUCTUREAL ZONE: cytoskeletal proteins (mainly actin and myosin) which form microtubules running under the membrane
  3. MEMBRANE SYSTEM: contains open canalicular systems (remnants of demarcation membrane systen) and dense tubular systems (remnants of MK RER) –> regulate intarplatelet Ca concentration
  4. ORGANELLE ZONE: contain mitochondria, glycogen deposits and granules:
    -alpha granules: contain fibrinogen/coagulation factors
    -dense granules: contain serotonin/ADP/ATP
    -lysosome granules: contain hydrolytic enzymes
28
Q

Description of primary and secondary hemostasis + the involvement of platelets in it

A
  1. Primary hemostatic plug: formed by the aggregation of platelets immediately after rupture of epithelium and exposure –> modulated by release od serotonin (vasocontriction), ADP and thromboxane (stimulate clumping)
  2. Secondary hemostatic plug: formed by release of alpha and dense granules of platelets –> triggers the clotting cascade ending in the conversion of soluble fibrinogen to insoluble fibrin which traps platelets in mesh.
29
Q

How are blood clots able to be removed?

A

Fibrinolysis via conversion of inactive plasminogen into active plamin, and other hydrolytic enzymes released from the lysosome granules of platelets themselves.

30
Q

5 types of leukocytes and their functions

A
  1. neutrophils: kill pathogens
  2. eosinophils: modulates local inflammation
  3. basophils: modulates inflammation and histamine release
  4. monocytes: adaptive immunity
  5. lymphocytes: immune response
31
Q

What are the characteristics that enable the identification of diff leukocyte types microscopically?

A
  1. Overall cell size and morphology
  2. Nucleus: size, position in cell, morphologt, staining properties, chromatin density
  3. Cytoplasm: staining properties, presence of absence of granules, dimension
32
Q

Description of process allowing leukocytes to move (6 STEPS)

A

DIAPEDESIS:
-intravasation is entering the circulation and extravasation is leaving it

PROCESS:
1. Upregulation in the expression of receptors (secretins) on the wall of postcapillary venules at the site of damage
2. PARTIAL tethering of WBC with secretins via glycoprotein ligands on their surface forming complexes with receptor on endothelium
3. Activation of integrins on WBC surface via cytokine release from endothelial cells to cause TIGHT binding
4. WBC extends protrusions (pseudopods) either through the paracellular or transcellular mechanism.
5. Upon entrance of WBC into CT chemotaxis allows migration to injury site
6. Once at the correct site, phagocytosis can occur

33
Q

What are the 2 types of mechanism for WBC diapedesis?

A
  1. PARACELLULAR:
    -protrusion of WBC occurs between cells that have lost their tight junctions
    -release of histamine, heparin and proteases by WBC to breach the basemement membrane
  2. TRANSCELLULAR:
    -protrusion of WBC occurs between cells that maintain their tight junctions
    -this requires formation of a trancellular pore within the endothelial cell via remodelling of endothelial plasma membrane

!! both types of mechanisms require energy input & path chosen is that of least resistance

34
Q

Characteristics of neutrophils

A

-most abundant
-segmented nuclei of 2-4 lobes (older cells tend to have more lobes)

3 types of cytoplasmic granules:

  1. azurophilic: contain myeloperoxidase, proteases and antimicrobial substances (cathelicidin peptide)
  2. specific: contain hydrolytic enzymes (collagenase/gelatinase) to break pathogen wall
  3. tertiary: contain gelatinase
35
Q

What are Barr Bodies?

A

-present in neutrophils of females
-dute to the presence of an inactivated X chromosome
-seen as a dark spot near the membrane of the neutrophil

36
Q

Process of neutrophil phagocytosis:

A

-Use of neutrophil receptors to identify pathogen antigens
RECEPTORS: Fc, toll-like
-Engulfing of pathogen by pseudopods to form a phagosome
-Combination with lysosome to form phagolysosome
-Cleavage of pathogen using hydrolytic enzymes
-Debris is released via exocytosis

37
Q

What is the Respiratory burst reaction?

A

RESPIRATORY BURST: significant increase in glucose and oxygen utilisation within neutrophil

-Method of killing pathogens within phagolysosomes using toxic reactive oxygen intermediates (ROIs) formed during respiratory burst
-NADPH oxidase complex and myeloperoxidases are used

38
Q

What are the possible defects that could affect the neutrophils ability to function? (3)

A
  1. Mutation to receptors for phagocytosis regognition
  2. Actin polymerisation defect (affects motility)
  3. Chemotaxis defect (affects migration)

!! all these defects would cause pathologies that exhibit high vulnerability to infections

39
Q

Pathology associated with neutrophils

A

CGD - chronic granulomatous disease:

-can either be X linked or autosomal recessive
-caused by a mutation in the components of NADPH oxidase complex
-no production of reactive oxygen radicals is possible
-causes autoimmune symptoms

40
Q

What is the miscroscopic difference between regular neutrophils and neutrophils during an infection?

A

NORMAL: lighter cytoplasm due to the presence of a normal amount of granules

INFECTION: very intensely stained cytoplasm due to active synthesis of granules for the lysis of the pathogen

41
Q

Characteristics of eosinophils

A

-bilobed nuclei
-contain eosinophilic granules containing histamine
-involved in allergic reactions

2 types of granules:

  1. Azurophilic (primary): lysosomes containing peroxidases
  2. Specific (secondary): crystalloid bodies containing Major Basic Protein (MBP)
42
Q

Characteristics of basophils

A

-bilobed nucleus
-darkly stained granules that slightly cover the nucleus
-involved in allergic reactions (granules contain histamine and heparin)
-contain many lysosomes
-closely related to mast cells in the sense that they both bind to IgE antibodies for the release of granules for allergic reactions

43
Q

Characteristics of monocytes

A

-kidney shaped nucleus
-precursors of macrophages
-mediate humoural response
-no granules present

44
Q

How can you differentiate between eosinophils and basophils microscopically?

A

-E contain red-ish (acidophilic) granules and B contains dark purple
-E has granules that are elongated crystalloids
-E has granules that NEVER cover the nucleus

45
Q

Characteristics of lymphocytes

A

-round shaped
-nucleus occupies almost the entire cell volume
-there are 3 groups based on the size: small/med/ large
-can migrate both into CT AND into lymphatic vessels

!!! Not terminally differentiated: differentie into T cells, B cells and NK (natural killer) cells

46
Q

Types of T lymphocytes and their roles

A
  1. Th: produce cytokines to modulate function of other cells
  2. Tc: lyse pathogen infected cells via lytic granule release in immunological synapses
  3. gamma/delta Tcells: boost innate response during inflammation or cancer
  4. T invariant: bridge innate and adaptive immunity
47
Q

Further denominations of T helper cells and their main characteristics (4)

A

! distinguisehed by the types of cytokines produced

Th17: kills extracellular bacteria
Th1: cell mediated immunity (autoimmune)
Th2: asthma/allergy response due to promotion of B cell into plasmoblast
Treg: tolerogenic - supresses excessive inflammation after infection

48
Q

Mechanisms by which T regulatory cells work

A

ROLE: supression of excessive inflammation:

  1. Inhibitory cytokine release
  2. cytolysis (pores permeating cell membrane)
  3. metabolic disruption (deprives effector cells of substances needed for their proliferation)
  4. Target dendritic cells (to prevent them from binding to effectors)
49
Q

Action of gamma/delta T lymphocytes

A

-contain 2gamma and 2delta units instead of the 2a/2b units of Th
-originate in thymus and can detect stresses from cells even if they are not of hematopoietic origin
!! ALSO CALLED INTRAEPITHELIAL CELLS: found in mucosa so they are the first defense
-continuously circulate in blood after release

EARLY PHASE OF ACTION: inante boost of response via cytokine release

LATE PHASE OF ACTION: downmodulation of immune response and release of trophic factors for tissue repair

50
Q

Action of MAIT cells

A

Mucosal associated invarient cells:
-have a restricted repertoire and can only identify antigen presented by APC for MR1 protein
-these are metabolites of BIBOFLAVIN that is derived from vitamin B in bacteria and fungi
-subsequence secretion of factors for destruction of infected cells

Histology (12 decks)

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