LABORATORY ACTIVITY 5 AND LABORATORY ACTIVITY 6 Flashcards
(139 cards)
1
Q
Within [?] after whole blood is allowed to clot in a clean glass tube at [?], the clot will begin to shrink and retract from the walls of the tube.
A
1 hour
37OC
2
Q
Serum is expressed and the clot becomes [?].
A
denser
3
Q
This retraction process is maximal at [?], by which time it occupies almost half of the original blood volume
A
24 hours
4
Q
PROCEDURE:
A
Modified MacFarlane Serum method
5
Q
- Collect [?] of venous blood samples. Note the time of collection.
A
5 ml
6
Q
- Dispense into a [?] noting exact amount of blood used.
A
graduated centrifuge tube
7
Q
- Place an [?] at the center of tube.
A
applicator stick
8
Q
- Incubate test tubes at [?] in a water bath for [?].
A
370C
2 hours
9
Q
- Examine and record degree of retraction (?)
A
partial, complete, or no retraction
10
Q
- Pull [?] with clotted blood and describe the clot.
A
applicator stick
11
Q
- Serum expressed is centrifuged for [?] at [?].
A
3-5 minutes
3,500 rpm
12
Q
- Calculate % of serum expressed as follows:
Volume of Serum =
% serum expressed =
A
total volume of serum in tube – volume of packed red cells
Volume of serum in ml/Volume of blood used in ml x (100)
13
Q
- Report results in
A
%
14
Q
This measures the time required for blood to clot after it has been removed from the body.
A
WHOLE BLOOD COAGULATION TIME
15
Q
This is a measure of the overall intrinsic and common pathways of coagulation.
A
WHOLE BLOOD COAGULATION TIME
16
Q
Micro Method –
A
capillary blood
slide method
17
Q
Macro Method –
A
Whole blood
Lee and White Method
18
Q
- Do a finger puncture. Start stopwatch at the time of appearance of [?] from the puncture
A
blood
19
Q
- Place on a clean glass slide [?]
A
3 separate drops of blood.
20
Q
- Allow to stand for [?] at room temperature. Check clot formation by drawing the blood with a needle or lancet and observe for thread formation.
A
2 minutes
21
Q
- Record [?] from the start to fibrin thread formation.
A
clotting time
22
Q
- Label three uniformly sized tubes [?].
A
1, 2 and 3
23
Q
- Make a clean venipuncture using [?] and note the time at which blood enters the syringe. Draw [?] of blood.
A
20-gauge needle
four (4) ml
24
Q
- Carefully dispense [?] to tube 3, then [?] to tube 2 and [?] to tube 1. [?] the remaining blood.
A
1 ml
Discard
25
4. Incubate all tubes in a water bath at
37 0C (+ 0.5 0C )
26
5. At exactly [?], tilt tube number 1 to a [?] angle and observe for clotting. Repeat every [?] until tube can be completely inverted without spilling contents. Note time of clotting.
5 minutes
450
30 seconds
27
6. After[?], tube 1 is clotted, proceed to tube 2 and repeat the preceding procedures. Repeat procedures with tube 3.
30 seconds
28
7. Record coagulation time as the time elapsed between the [?] and the [?] in tube 3.
withdrawal of blood
completion of coagulation
29
CLOT RETRACTION - otherwise known as
“contraction of clot”
30
CLOT RETRACTION - otherwise known as
“contraction of clot”
31
- requires great amount of ATP and Calcium
CLOT RETRACTION
32
- requires great amount of ATP and Calcium
CLOT RETRACTION
33
: compress to become denser
Contraction
34
: moves out of surface
Retraction
35
Mainly involves platelet
CLOT RETRACTION
36
In vivo or in vitro indication of plt function test (normal platelet function and number)
CLOT RETRACTION
37
Affected by both qualitative (inability to adhere) and quantitative (thrombocytopenia)
CLOT RETRACTION
38
based on platelet normal function
CLOT RETRACTION
39
: released by plt when activated; dense granules
ATP and Calcium
40
plt trapped in the clot releases [?] found in the cytoplasm of plt
factor XIII
41
= denser and more compact clot to be able to retract from the vessel wall
continuous cross-linking of XIII
42
: plays a role in contraction (retraction from the wall)
Calcium
43
allows platelet to go back to its original shape after contraction
Calcium
44
: produces energy
ATP
45
nonspeific screening test for in vivo plt function
CLOT RETRACTION
46
CLOT RETRACTION Principle:
When [?] is complete, clot normally undergoes [?].
blood coagulation
retraction
47
[?] is expressed and clot becomes [?]
Serum
denser
48
Normal clot retraction:
30 mins (initial)/24 hrs (completely/maximal)
49
contracts the clot
Platelet
50
Indication that clot has been retracted
Serum is expressed
51
Clot settles at the [?] or attaches to the applicator stick
bottom
52
happens before fibrinolysis
Clot retraction
53
before it dissolves
clot retracts
54
retraction does not mean the clot has been removed from the bv, but it simply [?] and proceeds to the bottom of the bv initiating plasmin to dissolve the clot = healing of bv
detaches
55
to preven thrombosis and establish blood flow
Fibrinolysis (dissolution of clot)
56
to give space for blood to start flowing again
Retraction
57
initially restores blood flow
Retraction
58
restored after fibrinolysis
Retraction
59
Factors affecting clot retraction
Adequate amount of plt
Calcium
ATP
Fibrinogen
normal interaction of plt and fibrinogen
60
(form platelet and bones)
Calcium
61
(from food, other cells, muscle breakdown)
ATP
62
adhesion of platelet to bv:
Ib-IX-V
63
adhesion of platelet to platelet:
fibronectin and fibrinogen
64
: plt will not aggregate = weak release of XIII
↓ Fibrinogen
65
plt needs to attach to the fibrin clot (no problem in the fibrin-plt interactiom)
normal interaction of plt and fibrinogen
66
normal interaction of plt and fibrinogen
qualitative defect
67
Other factors
thrombostenin
plasma volume: red cell mass
nature of the surface where CRT is being measured
68
contains actomyosin for muscle
thrombostenin
69
provides contractile force for plt
thrombostenin
70
stretches the plt
thrombostenin
71
equal in proportion
plasma volume: red cell mass
72
affects clot retraction if unequal
plasma volume: red cell mass
73
preferably glass = slower retraction in plastic; normal in glass(in vitro)
nature of the surface where CRT is being measured
74
prosthetic heart valve and fistula are dangerous since attachment of clot will not retract leading to obstruction of bv
nature of the surface where CRT is being measured
75
Process of Clot Retraction
Platelets → Thrombostenin → Actin/Myosin (Myosin II) → Clot retraction → BV edge retracts
76
[?] are entrapped in fibrin threads while continuously releases [?](initial release)
Platelets
FXIII along w/ Ca and ATP
77
plt changes in shape once denser via [?]
Thrombostenin
78
: releases microfilaments
Actin
79
(small filaments in plt that maintains shape; released by actin force)
microfilaments
80
: assembles microfilaments only in the surrounding/border of plt for support during change of shape
Myosin II
81
encodes Myosin II in the platelet
MYH9 gene
82
can make platelet have self-aggregation w/o fibronectin/fibrinogen
Myosin II
83
Once assembled, microfilaments will work on the
adhesion complex
84
(dissector of plt; connects plt to bv)
adhesion complex
85
to down-regulate it to help plt retract from the bv
adhesion complex
86
- adhesion complex; lacks in BSS; dissector of plt, down-regulating it; connects plt to bv
Gp Ib-IX-V complex
87
– plt starts to attach to fibrin links; bv is capable of contraction; plt, fibrin clot, bv
platelet spicules attached to fibrin
88
– by the help of FXIII
firbin meshwork
89
bv - conrtacts to help clot from detaching itself; capable of
contraction (bv vasoconstriction)
90
: action of plt, fibrin clot, and bv
blood retraction
91
to help eject the clot, the bv needs to constrict
BV edge retracts
92
CRT is poor when plt count is
<100,000/ul (thrombocytopenia)
93
Normal:
150-400uL
94
few plt trapped, few
thrombostenin
95
Clinical significance
Dysfibrinogenia
Hypofibrinogenemia
Paraproteinemias
96
: abnormal fibrinogen
Dysfibrinogenia
97
: low fibrinogen
Hypofibrinogenemia
98
: abnormal proteins
Paraproteinemias
99
plt needs to adhere to fibrinogen to allow interaction between them)
Dysfibrinogenia
100
plt has nowhere to attach to for fibrin-meshwork formation; no retraction will take place)
Hypofibrinogenemia
101
Abnormal thrombostenin: actin-myosin function will not occur (release and assembly of filaments)
Paraproteinemias
102
Methods
a. Hirschboeck Method (Castor oil Method)
b. Stefanini Method (Test tube)
c. Mac Farlane Method
103
Qualitative: Test for the presence or absence of retraction
Hirschboeck Method (Castor oil Method)
104
Formation of dimpling/droplet like serum on the surface of blood drop
Hirschboeck Method (Castor oil Method)
105
Normal Values = 15 - 45 minutes
Hirschboeck Method (Castor oil Method)
106
Normal: clot retraction begins within 1 hour, complete within 18 to 24 hours
Stefanini Method (Test tube)
107
Provides quantitative estimate of the degree of retraction
Mac Farlane Method
108
Degree of serum expressed = Degree of retraction
Mac Farlane Method
109
Normal Values = 44% - 67 %
Mac Farlane Method
110
COAGLULATION TIME - otherwise known as
“clotting time”
111
COAGLULATION TIME - Principle: measures the [?] for blood to clot after it has been removed from the body within [?]
time requires
1 hour
112
COAGLULATION TIME Indication
Factor deficiency
Hemophilia A and B
Does not diagnose mild coagulation disorder
Traumatic
Not reliable
113
it is a nonspecific screening test for intrinsic and common pathway factor deficiencies = prolongs coagulation time
Factor deficiency:
114
: severe deficiency of factor VIII (A) and IX (B) = prolongs coagulation time in intrinsic pathway
Hemophilia A and B
115
screening test: not affected by mild deficiency (nonspeific)
Does not diagnose mild coagulation disorder
116
normal coagulation time in minimal factor deficiencies
Does not diagnose mild coagulation disorder
117
puncture of finger
Traumatic
118
not reproducible; cannot be done on the same person
Not reliable
119
cannot detect mild factor deficiencies
Not reliable
120
after the prick, blood will automatically suck in the capillary
Capillary method
121
break the capillary and note the time
Capillary method
122
NV: 2-4 minutes
Capillary method
123
add the blood and start the timer
Tube method
124
keep on tilting the tube every 30 seconds to see clot formation
Tube method
125
NV: 7-15 mins
Tube method
126
Factors affecting Clotting Time
Macromethod
127
Excessive agitation of the tube:
shortens clotting time
128
:
(allowing FXII to have contact with glass = activation of negative surface or glass)
Excessive agitation of the tube
129
no quality control: no comparison to a basis; not reliable
Macromethod
130
not considered as adequate test: affected by factors such as the glass surface
Macromethod
131
Causes Of Prolonged Clotting Time Are
Coagulation factors deficiencies which may be: Congenital or Acquired
Severe deficiency of any known plasma clotting factors except XIII (fibrin-stabilizing factor) and VII
Drugs like heparin and thrombin inhibitors
Marked hyperheparinemia
Afibrinogenemia
132
(extrinsic pathway; in vivo)
VII
133
(normal clotting time; does not help in clot formation)
XIII
134
: does not cause bleeding disorder but may cause prolonged clotting time
FXII
135
Anti-thrombin (heparin, warfarin, Coumarin)
prolongs clotting time
136
Excessive heparin in the system - attacks thrombin = coagulation cascade failure =
prolongs clotting time
137
No fibrinogen = No plt plug = No conversion of fibrinogen to fibrin =
Prolongs clotting time
138
Blood clotting mechanism
Three stages
Vascular spasm
Platelets plug formation
Congulation factors activation
139
Stages of blood clotting
Formation of protrombinase:
1. Intrinsic pathway
2. Extrinsic pathway
Prothrombin —-> Thrombine (enzyme)
Fibrinogen (soluble) ——> Fibrin (insoluble)
