Lecture 21 - Hemostasis Flashcards
1
Q
what are blood groups determined by?***
A
presence or absence of specific marker molecules on the cell membrane of RBCs
2
Q
what are antigens?
A
substances that the body does not recognize as belonging to the “self
3
Q
what do antigens trigger?
A
defensive response from the immune system
4
Q
what are antigens made of
A
generally large proteins, but can include carbohydrates, lipids and nucleic acids
5
Q
what are antibodies also called
A
immunoglobulins
6
Q
what are antibodies produced by
A
plasma cells
7
Q
what do antibodies do
A
attach to specific antigens
8
Q
our bodies produce antibodies in response to what?
A
in response to foreign antigens
9
Q
is the antibody-antigen response induced?
A
yes
10
Q
name 2 groups of antigens on RBCs that may cause significant harm to patients
A
ABAO blood group and Rh blood group
11
Q
ABO blood typing designates the presence/absence of which 2 antigens
A
A and B antigens
12
Q
what type of proteins are A and B antigens
A
glycoproteins
13
Q
how are ABO blood types determined
A
genetically
14
Q
Blood type A has antibodies to….
A
antibodies to B antigen in blood plasma: anti-B antibodies
15
Q
an individual with type B blood has which tupe of naturally formed antibodies
A
anti-A antibodies
16
Q
an individual with blood type AB has which naturally formed antibodies
A
they have both A and B antigens so do not have naturally formed antibodies to either of these
17
Q
people with blood type O have which kind of antibodies and antigens presence
A
lack A and B antigens on their erythrocytes, both have both anti-A and anti-B antibodies circulating in blood plasma
18
Q
what initiates the formation of antibodies
A
body must first be exposed to the foreign antigen before an antibody can be produced
19
Q
how is the human immune system exposed to A and B antigens at an early age
A
ABO blood group antigens are found in foods and microbes throughout nature, exposed at an early age –> antibodies are formed naturally
20
Q
describe the series of events following a transfusion of incompatible blood
A
- RBCs with foreign antigens appear in the blood stream –> trigger an immune response
- antibodies attach to the antigens on the membranes of the transfused RBCs
-agglutination: Y shaped antibodies attach randomly to more than one foreign RBC –> form clumps
21
Q
what are the consequences of agglutination in the body
A
- clumps block small blood vessels throughout the body –> deprive tissues of oxygen and nutrients
- hemolysis: as erythrocyte clumps degrade –> hemoglobin released into blood stream
-load of hemoglobin released can be toxic to the kidney –> quickly develop kidney failure
22
Q
anti-B antibodies will cause agglutination and hemolysis if…
A
they ecounter erythrocytes with B antigens
23
Q
anti-A antibodies will cause agglutination and hemolysis if…
A
they encounter erythrocytes with A antigens
24
Q
if a blood sample agglutinates with both anti A and anti B antibodies, what is the ABO type?
A
AB
25
if a blood sample agglutinates with anti-B antibodies but not anti-A antibodies, what is the ABO blood type?
B
26
if a blood sample only agglutinates with anti-A antibodies, what is the bloodtype?
A
27
If the blood sample does not agglutinate with anti B nor anti A antibodies, what is the blood type
O
28
Type A...
antigens on blood cells:
antibodies in plasma:
Donates to:
receives from:
antigens on blood cells: A
antibodies in plasma: B
Donates to: A, AB
receives from: A, O
29
Type B...
antigens on blood cells:
antibodies in plasma:
Donates to:
receives from:
Type B...
antigens on blood cells: B
antibodies in plasma: A
Donates to: B, AB
receives from: O, B
30
Type AB...
antigens on blood cells:
antibodies in plasma:
Donates to:
receives from:
Type AB...
antigens on blood cells: A, B
antibodies in plasma: none
Donates to: AB
receives from: universal acceptor
31
Type O...
antigens on blood cells:
antibodies in plasma:
Donates to:
receives from:
antigens on blood cells: none
antibodies in plasma: A, B
Donates to: universal donor
receives from: O
32
Rh blood group is classified according to what
presence, or absence of a erythrocyte antigen Rh
33
in what animal was the Rh antigen first discovered
rhesus macaque
34
which Rh antigen is clinically important
although dozens have been identified, only D is clinically important
35
What determines wether someone is Rh+ vs. Rh -ve
Rh+ = D antigen present on erythrocytes
Rh- = lack D antigen on erythrocytes
36
when are Rh antibodies produced? contranst this to ABO antibodies
antibodies to Rh antigen are produced in Rh- individuals only after exposure to the antigen vs. ABO group antibodies which are preformed
37
what are 2 ways in which Rh antibodies may be formed in an Rh negative individual
following a transfusion with incompatible blood, or birth of an Rh+ baby to an Rh- individual
38
what happens when an Rh- individual gives birth to an Rh+ baby, given that this is their second Rh+ve baby
immediately after the first birth, the Rh- parent would be exposed to baby's Rh+ cells --> immune system of parent begins to generate anti-Rh antibodies after exposure --> during second pregnancy, Rh antibodies produced can cross the placenta into fetal blood stream and destroy fetal RBCs
39
describe the action and mechanism of RhoGAM
action: temporarily prevent the development of Rh antibodies in the Rh- parent
MechanismL antibodies destroy any fetal Rh+ erythrocytes that may cross the placental barrier
40
how many blood groups are there in dogs
more than 12, their RBCs may contain any combination of these b/c each blood group is inherited independently
41
what is the most important dog blood group
Dog erythrocyte antigen (DEA) 1.1
42
do dogs normally have antibodies against other canine blood group antigens
normally, dogs do not have any antibodies against any of the antigens present in their own blood or other canine blood group antigens unless previously exposed to them via. transfusion
43
how many known blood types are there in cats? name them!
4: A, B, AB, mic
44
what is the most common blood group in cats? what about the others?
A = most common
B = higher in certain breeds
AB = rare
45
do cats have antibodies against blood group antigens they lack
yes
46
what is the universal donor amongst cats
there is no universal donor
47
How many blood groups are there in horses? name them!
7: A,C,D,K,P,Q,U.
48
each blood group in horses can have multiple cell membrane proteins. what are they referred to as?
A to G
49
how many allelic combinations of blood types can horses have
400,000
50
do horses possess antibodies against RBC antigens that they do not possess
no, unless they are exposed to a different blood type (ex. transfusion)
51
which animals is crossmatching for blood types not necessary for the first transfusion?
dogs, horses
52
Define hemostasis
process by which the body seals a ruptured blood vessel and prevents further loss of blood
53
what is hemostasis effective in dealing with
small, simple wounds
54
name the 3 steps of hemostasis in sequence... what happens when there is a failure in any one of these steps
1.vascular spasm,
2.formation of a platelet plug,
3. coagulation (blood clotting )
failure = hemorrhage
55
describe vascular spasm
platelets secrete vasoconstrictors that cause vascular spasms in broken vessels
56
describe the formation of temporary platelet plugs to stop bleeding
- collagen fibers are exposed
- platelets become sticky and release chemicals to attract more platelets
- 'plug' is formed that slows loss of blood within 3-5 minutes
57
describe coagulation
- clotting factors in blood reinforce platelet 'plug'
- calcium needed
chemical reactions --> form thrombin (enzyme)
- thrombin joins fibrinogen into netlike fibrin
- blood cells are trapped in fibrin meshwork to form a hard clot
58
different precursors of fibrin polymer
fibrinogen --> fibrin --> fibrin polymer
59
what are 4 critical components to coagulation***
prothrombin --> thrombin --> fibrinogen --> fibrin
60
how many stages are there in coagulation
3
61
when are clotting factors activated
- blood vessels are broken
62
are clotting factors active or inactive in blood
inactive
63
clotting factors are primarily secreted by ____ and _____
liver and platelets
64
what does the the liver require to produce clotting factors
fat soluble vitamin K
65
what is a common cofactor required by clotting factors
calcium ion as a cofactor
66
What happens in stage 1 of the coagulation pathway
production of active thrombokinase by the extrinsic and intrinsic pathway
67
describe where chemicals are released from in the extrinsic pathway
chemicals are released from damaged tissues
68
describe where chemicals are released from in the intrinsic pathway
chemicals present in blood
69
do both pathways need to be activated for effective homeostasis?
yes
70
what happens in stage 2 of the blood coagulation pathway
conversion of prothrombin to thrombin by the thrombokinase produced in stage 1
71
what happens in stage III of the blood coagulation pathway
conversion of fibrinogen to fibrin and production of fibrin clot by thrombin produced in stage II
72
Fibrinogen:
Type of molecule: ?
Source: ?
Pathways: ?
Fibrinogen:
Type of molecule: plasma protein
Source: Liver
Pathways: common, converted into fibrin
73
Prothrombin:
Type of molecule: ?
Source: ?
Pathways: ?
Prothrombin:
Type of molecule: plasma protein
Source: liver*
Pathways: common; converted into thrombin
73
What are 2 conditions that hasten clotting?
- rough spot in the blood vessel lining
- abnormally slow blood flow
73
what are 2 conditions that oppose clotting
- smooth surface of lining of blood vessels does not allow platelets to stick
- antithrombins: substances in blood that oppose or inactivate thrombin (ex. heparin)
74
Thrombosis
abnormal clotting of blood in an unbroken vessel
75
thrombus:
a clot that attaches to the wall of the blood vessel
76
embolus
a clot that comes off the wall of the blood vessel and travel in blood stream (travels to small vessel and blocks flow)
77
embolism
blockage of blood flow by an embolus that lodges in a blood vessel
78
infarction
cell death that results from embolism
- is responsible for most strokes and heart attacks
79
what are 3 bleeding disorders
1. thrombocytopenia
2. deficiency of clotting factors due to impaired liver function
3. hemophilias
80
what is thrombocytopenia
the number of circulating platelets is deficient (<50,000/ul)
81
what does thrombocytopenia cause
spontaneous bleeding from small vessels all over the body
82
what are hemophilias
hereditary bleeding disorders due to deficiency of clotting factors
83
what does aspirin do
thins blood, can prevent heart attack and stroke
84
what is the aPTT test used to evaluate
intrinsic pathway: evaluates the coagulation factors XII, XI, IX, VIII, X, V, II (prothrombin and fibrinogen)
85
what is the PT test used to evaluate
extrinsic pathway: evaluates coagulation factors VII, X, V, II and I (fibrinogen)
86
how is a PT test conducted
- a sample of patients blood is obtained and centrifuged.
- PT test is performed by adding patients plasma to some source of tissue factor
- kept in a water bath at 37*
- test is timed until the plasma clots (prothrombin time)
87
what does a prolonged prothrombin time indicate?
indicates a deficiency in any factors VII, X, V, prothrombin or fibrinogen
88
how is an aPTT test conducted
- activating substances added to plasma to start the intrinsic pathway of the coagulation cascade
- measure partial thromboplastin
89
what is partial thromboplastin
the time it takes for a clot to form, measured in seconds
90
how long should prothrombin time be
~12 seconds
91
how long should partial thromboplastin time take
25-39 seconds
92
what does aPTT measure***
measures the integrity of the intrinsic system and common clotting pathways
93
GIRL you better know everything about PT and PTT tests!!
94
increased levels of PT or aPTT means...?
a clotting factor may be missing or defective
95
which pathway is affected if PT is prolonged but aPTT is normal
extrinsic
96
which pathway is affected if PT is normal but aPTT is prolonged
intrinsic (and common????????????????? lmk if you know the definite answer)
97
which pathway is affected if both PT and aPTT are affected
common or ...?????? ( again lmk if another one is affected)
