blood disorders Flashcards
1
Q
Mean corpuscular volume
A
the average volume of a single red blood cell
2
Q
fL
A
units for MCV - fentolitres
3
Q
mean corpuscular haemoblobin concenration
A
the average haemoglobin concentration in a single red blood cell in g/L
4
Q
Colour index (CI)
A
the ratio of the % of haemoglobin to the RBC count.
5
Q
the ‘normal’ haemoglobin % count
A
150g/L
6
Q
the ‘normal’ RBC count
A
5 T/L
7
Q
if CI < 1
A
hypochromia
8
Q
if CI = 1
A
Normochromia
9
Q
if CI > 1
A
Hyperchromia
10
Q
MCV < 80fL
A
microcytic anaemia
11
Q
MCV = 80-100fL
A
normocytic anaemia
12
Q
MCV > 100 fL
A
macrocytic anaemia
13
Q
poikilocytosis
A
nonuniformity of cell shapes
14
Q
anisocytosis
A
nonuniformity of cell sizes
15
Q
most common causes of anaemia
A
- blood loss
- inadequate RBC production
- Excessive RBC destrucstion (haemolysis)
16
Q
nutritional deficiencies causing anaemia can lead to
A
- impaired DNA synthesis
- impaired haemoglobin synthesis
17
Q
iron deficiency anaemia
A
caused by the loss of iron through blood loss from the genitourinary tract
18
Q
iron homeostasis
A
regulated through controlling absorption of iron. whereas iron loss/excretion is NOT under control
19
Q
functional iron
A
- 80% haemoglobin.
- 20% myoglobin and iron containing enzymes
20
Q
site of iron absorption
A
duodenum in the forms of heme and nonheme iron molecules
21
Q
iron molecules bind to a protein called..
A
ferritin, as iron in its free form is toxic.
22
Q
hepcidin
A
inhibits iron transfer from the enterocyte to plasma by binding to the ferroportin and causing it to be degraded
23
Q
transferrin
A
a binding protein hat transports iron to the plasma
24
Q
apo-transferrin
A
the protein without a binded iron
25
ferritin content in the blood
can help identify the iron supply in the body
26
haemosiderin
granules formed as a result of the degradation of ferritin protein shells
27
heme synthesis
ferrous iron + protoprphyrin IX (with presence of ferrochelatase)
28
pernicious anaemia
stems from a vitaminb12 deficiency, impairs cell division, does not affect haemoglobin synthesis
29
stores for vitaminb12
there are significant intrahepatic stores which last for several years
30
which food groups contain little vitaminb12
plants &vegetables
31
intrinsic factor
required for the absorption of vitaminb12.nintrinsic factor is produced by the parietal oxyntic cells of the stomach
31
32
transcobalamin II
associates with vitaminb1 and delivers it to the liver and other cells of the body
33
haptocorrin
a salivary protein that binds to vitaminb12 for transportation
34
achlorhydria and loss of pepsin secretion
vitaminb12 is not readily released by proteins in food
34
gastrectomy
intrinsic factor is not available for uptake in the ileum
35
loss of exocrine pancreatic function
vitaminb12 cannot be released from haptocorrin-vitaminb12 complexes
36
ileal resection or diffuse ileal disease
can remove or damage the site of intrinsic factor-vitaminb12 complex absorption
37
tapeworms
compete with the host for b12 and can induce a deficiency state
38
pregnancy, hyperthyroidism, disseminated cancer, and chronic infection
an increased demand for vitaminb12 can produce a relative deficiency even with normal absorption
39
which 2 biochemical processes is vitaminb12 required for
physiological lipid metabolism and DNA synthesis
40
macro-ovalocyes
larger than normal RBCs and contain ample haemoglobin. they lack the central pallor of normal RBCs and even appear hyperchromic
41
cell characteristics of pernicious anaemia
-significant anisocytosis and poikilocytosis
- nucleated precursors in peripheral blood
- macro-ovalocytes
- hypersegmented neutrophils
42
megaloblasts
large nucleated RBCs found in bone marrow following pernicious anaemia
43
stores of folate
are modest
44
sickle cell anaemia
common hereditary haemoglobinopathy caused by a point mutation in beta-globin that promotes the polymerisation of deoxygenated haemoglobin, leading to red cell distortion, hemolytic anaemia, microvascular obstruction, and ischaemic tissue damage
45
HbA1 abundancy
>95%
46
HbA2
<3.5%
47
HbF
1-2%
48
HbS containing RBC characteristics
rigid and tend to adhere to each other, they form plugs in small blood vessels and easily fall apart. However, RBCs in heterozygous individuals do not sickle except under conditions of profound hypoxia
48
aplastic anaemia
chronic primary haematopoietic failure and attendant pancytopenia
49
haemolytic anaemias key features
- shortened RBC lifespan
- elevated erythropoietin levels and a compensatory increase in erythropoiesis
- accumulation of haemoglobin degradation products
49
erythropoietin (EPO)
a glycoprotein hormone, naturally produced by the peritubular cells of the kidney, that stimulates RBC production
50
erythropoiesis
the process of making RBC
51
extravascular haemolysis
- slenomegaly
- anaemia
- jaundice
52
intravascular haemolysis
- haemosiderinuria
- anaemia
- haemoglobinaemia
- haemoglobinuria
- jaundice
- no splenomegaly
53
reticulocytosis
an increase in circulating reticulocytes
54
reticulocytes
immune RBCs produced in the bone marrow and released into the peripheral blood
55
extramedullary haematopoiesis
refers to deposits of erythroid precursors in sites other than the bone marrow and peripheral blood
56
platelets
platelet membranes are sources of phospholipids and contain receptors that are needed for platelet aggregation
57
platelet activation
inititated by exposure to thrombin, collagen and platelet-activating factor (PAF)
58
main phases of haemostasis
1. Vascular phase
2. Platelet phase
3. Coagulation phase (thrombus formation)
59
coagulation factors
most are produced by the liver but some derive from endotheleal cells and platelets.
60
stages in secondary haemostasis
1. initiation
2. amplification
3. propagation
61
thromboplastin
released by damages cells during coagulation, this activates factor VII
62
fibrinolysis
fibrin is degraded by plasmin
63
excessive bleeding
- increased fragility of BV
- platelet deficiency or dysfunction
- derangement of coagulation
64
megakaryocytes
large progenitor cells in the bone marrow, are the source of platelets
65
haemarthrosis
bleeding due to coagulation factor deficiencies often occurs into the gastrointestinal and urinary tracts and into weight-bearing joints
66
inherited clotting factor deficiencies
- haemophilia A
- Von Willeband disease
- haemophilia B
67
Aquired clotting factor deficiencies
- decreased protein sythesis
- shortened half life
68
multiple clotting factors affected
aquired clotting factor deficiencies
69
a single clotting factor is affected
inherited clotting factor deficiencies
70
Von Willebrand disease
An autosomal dominant disorder, spontaneous bleeding from mucous membranes, wounds or menorrhagia, often goes unnoticed until some haemostatic stress occurs.
71
haemophillia A
X-linked recessive hereditary disease resulting in life-threatening bleedings.
72
haemophilia B
X-linked recessive inheritance
73
prothrombin time (PT)
measurement in seconds of the clotting of plasma after addition of an exogenous source of tissue thromboplastin and calcium ions.
assesses the extrinsic and common coagulation pathways
74
partial thromboplastin time (PTT)
the clotting of plasma after the activation of contact factor XII.
assesses the intrinsic and common coagulation pathways
75
Disseminated intravascular coagulation (DIC)
- triggered by overwhelming infection, specific leukemias or lymphomas, or massive haemorrhage
- aberrant activation of the clotting system results in microthrombi at various location
- because all clotting factors have been consumes, no blood clotting can occur where it would be needed.
