heme Flashcards Preview

clin med > heme > Flashcards

Flashcards in heme Deck (86):
1

major functions of blood

transport (O2, CO2, nutrients, hormones)

immunity (WBCs)

hemostasis (stop bleeding)

homeostasis (provide optimal environment to
maintain steady state (pH, ions, temp, nutrient supply)

2

main role of RBCs

transportation of oxygen

3

how long do RBCs survive?

4 months (120 days)

4

precursor RBC in bone marrow

erythroblast

5

what are platelets?

essential for blood coagulation
much smaller than leukocytes
represent bits of the cytoplasm of megakaryocytes
largest precursor cells in the bone marrow
short survival, about 10 days

6

most numerous of the WBCs in an adult

neutrophils

7

what are bands?

slightly less mature neutrophils that have a non-segmented or band-shaped nucleus - neutrophils which have just been released from the bone marrow

8

sites of hematopoiesis

yolk sac
liver and spleen
bone marrow

9

what is a granulocyte?

WBC that is filled with microscopic granules
little sacs containing enzymes that digest microorganisms

innate immune system

10

role of basophil

secretory cell which mediates the hypersensitivity reaction

11

what is the largest cell in the peripheral blood?

monocytes

12

which WBCs are referred to as mononuclear?

monocytes and lymphocytes

13

what is the flexible inner protein fiber in RBCs?

spectrin

14

hematopoiesis occurs in the red bone marrow of what?

axial skeleton and girdles

epiphyses of the humerus and femur

15

Erythropoietin (EPO) release by the kidneys is triggered by:

Hypoxia due to decreased RBCs
Decreased oxygen availability
Increased tissue demand for oxygen

16

where does the body get iron from?

stores iron in Hb, the liver, spleen, and bone marrow

intracellular iron is stored in protein-iron complexes such as ferritin and hemosiderin

circulating iron is loosely bound to the transport protein transferrin

17

where does RBC breakdown occur?

spleen - dying RBCs are engulfed by macrohages. heme and globin are seperated and the iron is salvaged for reuse

18

what is heme degraded into?

Fe recycled ot ferritin or hemosiderin

yellow pigment called bilirubin

19

what is hematocrit?

portion of total blood volume that is RBC

20

what is MCV?

mean corpuscular volume - average volume/size of a single RBC

21

abnormal variation in cell volume

anisocytosis

22

when will you see target RBCs?

iron deficiency
liver disease
spleen removal
thalassemia

*densely stained central area with a pale surrounding area

23

what are platelets?

cytoplasmic fragments of megakaryocytes - in adults megakaryocytes are exclusively in the bone marrow

24

what is thrombopoeitin?

promotes the grown of Meg-CFC
increases the rate of endomitosis
inhibits apoptosis
stimulates magakaryocyte maturation

25

does thrombopoeitin promote platelet release?

no

26

what inhibits platelet aggregation?

cyclic AMP
- Cyclic AMP increased by prostoglandins

27

what do anti-platelet drugs do?

interfere with prostaglandin synthesis
Aspirin, NSAIDS - COX1 inhibitor
Celebrex - COX 2 inhibitor

interfere with cyclic AMP, ADP binding, and inhibition of the GPIIb/IIIa receptor

28

acquired platelet dysfunction is from what?

liver disease
cadiopulmonary bypass
uremia
dysproteinemia
myeloproliferative disorders (bone marrow)
alcohol toxicity

29

inherited platelet dysfunction

giant platelet disorders
Wiskott-aldrich syndrome
storage pool disorders
glanzmann thrombasthenia
platelet release disorders

30

what is thrombocytopenia?

reduced platelet count in peripheral blood

31

what causes thrombocytopenia?

increased destruction**
decreased production
abnormal pooling or distribution within the body
artifact

32

what is pseudothrombocytopenia?

conformational change in plt membrane
Immune clumps the platelets
cold dependent clumping

*evaluate with smear

33

what is ITP?

immune thrombocytopenic purpura
also called idiopathic autoimmune thrombocytopenic purpura
occurs in both children and adults
caused by platelet specific antibodies which bind to the platelets

34

this mediates adhesion of platelets to the collagen exposed on endothelial cell surfaces

von willebrand factor - acts as a bridge between a specific glycoprotein complex on the surface of platelets and collagen fibrils

35

vWF is required to bind to and stabilize coagulation factor what?

VIII

36

what is aggregation?

binding to other platelets via fibrinogen

37

aggregation is mediated by what?

fibrinogen receptors (GPIIb/IIIa)- undergo conformational change to active state

38

goal of clotting cascade

form fibrin

39

this is initiated when contact is made between blood and exposed negatively charged surfaces

intrinsic cascade

40

this is initiated upon vascular injury which leads to exposure of tissue factor

extrinsic pathway

41

what pathway does aPTT (activated partial thromboplastin time) evaluate?

intrinsic

42

what pathways doe PT/INR (prothrombin time) evaluate?

extrinsic

43

factors determining hemoglobin values

age
gender
race
degree of sexual maturation
altitude
heredity

44

what does a high retic count indicate?

bone marrow is trying to compensate for anemia

45

symptoms of iron deficiency anemia

asymptomatic
weakness, fatigue, SOB, pallor, dizziness, irritability, decreased exercise tolerance
pica - severe state (ice craving)
palor
koilonychia
tachycardic
glossitis

46

what is sideroblastic anemia?

iron fails to bind to pophyrin ring in the erythroblast to produce heme

iron is retained in the mitochondria of the cell

ringed sideroblasts (normoblast with perinuclear halow of blue-stained material) seen on bone marrow smear with prussian blue staining

47

what is sideroblastic anemia characterized by

anemia
low retic count
ineffective erythropoiesis with distinctive mophology

48

treatment of sideroblastic anemia

remove offending agent
trial of pyridoxine to correct nutritional deficience

49

what are folate and B12 required for?

DNA synthesis and regulation

50

B12 and folate deficiency anemia results in what?

megaloblastic anemia due to reduced DNA replication

51

clinical manifestations of folate deficiency

jaundice due to ineffective erythropoiesis
smooth tongue

52

lab findings for folate and cobalamin deficiency

macrocytosis
howell-jolly bodies
relatively low retic count
mild thrombocytopenia and/or neutropenia
hypersegmentation of neutrophils
megaloblastic changes in marrow

53

will magaloblastic anemia of B12 deficiency respond to folic acid in high doses?

yes, but neurologic deficits do NOT respond

54

what is anemia of chronic disease?

occurs in setting of chronic disease states associated with inflammatory cytokines or impaired marrow production

induce production of hepcidin - blocks iron absorption from gut

55

causes of anemia of chronic disease

acute and chronic infections
inflammatory and autoimmune diseases (T-cell mediated)
cancer
CKD
liver disease
MDS (myelodysplastic syndromes)
aging

56

what is aplatic anemia

failure of bone marrow due to injury or abnormal expression of pluripotent hematopoietic stem cell

hallmark: bone marrow shows hypocellularity and hypoplasia of all cell lines

57

most common cause of non-immune hemolytic anemia

hereditary spherocytosis

58

manifestations of sickle cell disease

chronic hemolytic anemia
pain
dactylitis
acute chest syndrome
chronic organ damage (spleen, brain, kidneys)

59

most frequent reason for sickle cell hospitalization

vaso-occlusive pain crisis
severe, agonizing pain usually starting in limbs

60

transfusion indications in sickle cell

acute stroke or TIA
acute chest syndrome
priapism
splenic sequestration
pre-operative
sympotomatic anemia
aplastic crisis
abnormal transcranial doppler

61

what is not indicated for a sickle cell transfusion?

pain crisis
anemia

62

neonatal factor assays for hemophilia

should be performed on male infants with a family hstory of bleeding problems or prolonged bleeding after circumcision

hemophilia A - can be diagnosed from FVIII levels in CORD BLOOD collected immediately after delivery

hemophilia B- requires blood to be taken after 6 months of age since FIX is vitamin-K dependent and all neonates have low levels of vitamin K and FIX

63

what should you avoid in patients with severe pain due to bleeding in joints?

aspirin and NSAIDS - can exacerbate bleeding

64

what is DIC characterized by?

clotting and bleeding

systemic activation of coagulation system results in overactivation of the fibrinolytic system

-clotting due to circulating thrombin
-bleeding due to depletion of clotting factors and excessive fibrinolysis

65

why do you have platelet dysfunction in coagulopathy of liver failure?

splenomegaly due to portal hypertension - sequesters platelets

ETOH cirrhosis- suppression of thrombopoeisis by toxicity of alcohol or concomitant folate deficiency

66

where are you clotting factors made?

liver - except VWF

67

what is the best prognostic indicator in Acute liver failure?

factor V level- helps determine need for urgent transplant in patient presenting with encephalopathy

68

treatment of coagulopathy in liver failure

not curative, only supportive

novoseven (recombinant human factor VII) - off label use in liver disease but use is restricted due to limited data and excessive cost

69

what coag factors are dependent on vitamin k?

II, VII, IX, X

70

what is virchow's triad?

pathrogenesis of a thrombus

endothelial injury
abnormal bloodflow
hypercoagulability (primary - genetic or secondary - acquired)

71

what signs/symptoms are indicative of a DVT?

painful, swollen, warm and plethoric extremity with reduced pulse volume

72

what signs/symptoms are indicative of a PE?

cough, SOB, hemoptysis, tachycardia

73

hypercoagulable state workup for primary

protein C activity - impaired inactivation of factors V and VIII -->unregulated fibrin production

protein S activity - impaired inactivation of factors V and VIII -->unregulated fibrin production

antithrombin III - major inhibitor of thrombin and fibrin formation

factor V leiden

74

hypercoagulable state workup for secondary

anticardiolipin antibody
lupus anticoagulant
homocysteine

75

what is factor V leiden mutation?

activated protein C resistance

point mutation in gene for Factor V renders it unable to be inactivated by protein C

76

primary HCS screening guidelines

VTE

77

primary HCS treatment

heparin drip until therapeutic with warfarin

goals: 2-3

78

primary HCS duration of tratment

first VTE episode: 6-12 months
recurrent VTE: lifelong therapy

79

who is likely to have antiphospholipid syndrome

often associated with Lupus
recurrent pregnancy loss

80

what is antiphospholipid syndrome?

autoantibodies directed against phospholipids in cell membranes lining blood vessels

induces endothelial cell damage, predisposing to thrombosis - starts coag cascade with no tissue damage

81

what should you suspect in patients with prolonged aPTT with no clinical bleeding?

lupus antigoagulant - clinically not a bleeding disorder. just an antibody that prolongs aPTT by binding to phospholipid in the lab assay

82

what are mixing studies used for?

performed on blood plasma used to distinguish factor deficiences from factor inhibitors

83

what are the primary lymphoid organs?

thymus and bone marrow

84

what are the secondary lymphoid organs

spleen
MALT
lymph nodes
tonsils

85

what is the complication from tumor lysis syndrome (TLS)?

marked increase in uric acid excretion can result in ACUTE RENAL FAILURE

- occurs with rapid release of intracellular potassium and phosphorous into blood stream

86

diagnostic tests for tumor lysis syndrome

LFT and LDH
uric acid
renal function test
serum electrolytes
EKG if hyperkalemic