Week 1: Wednesday Flashcards
1
Q
what is the role of endothelium
anticoagulant
A
favors anticoagulant mechanisms
* has smooth surface
* negative charge
2
Q
what does the endothelium produce
A
- vasodilators
- inhibitors of coagulation
3
Q
what is the role of endothelium in procoagulant properties
A
- vasocontriction
- disruption of endothelial integrity (exposes collagen - activates primary hemostasis; tissue factor - activates secondary hemostasis)
- synthesizes pro-thrombotic factors (Von Willebrand factor)
4
Q
what is primary hemostasis
A
- formation of the primary platelet plug
- interaction with endothelium (exposure of collagen)
- provide surface for coagulation factors (secondary hemostasis)
5
Q
what are platelets
A
- produced in bone marrow
- lifespan - 6 days
- pre-formed substances in platelet granules (enhance platelet function and attract more platelets to site)
6
Q
how do plateletes work
A
- damage to vessel wall (exposure of collagen)
- adhesion
- activation
- aggregation
7
Q
what is platelet adhesion
A
- dependent on local blood flow
- static or low speed flow - platelets adhere to collagen of sub-endothelium
- high speed flow - von Willebrand factor mediated platelet adhesion
8
Q
what is von willebrand factor (VWF)
A
- synthesized by megakaryocytes and endothelial cells
9
Q
what is the function of VWF
A
- mediator of platelet adhesion in rapid blood flow conditions
- decrease of factor VIII clearance
10
Q
what is platelet activation
A
- happens secondary to adhesion (collagen) or agonist mediated activation
- thrombin (CF II) is biggest activator
- shape change - pesudopodia
- release of platelet granules (attract, activate more platelets)
11
Q
what is platelet aggregation
A
- platelets interact to provide the surface for coagulation factors
- hemostatic plug
- linked to each other by fibrinogen
12
Q
what are the signs of primary hemostasis
A
- petechiation, ecchymoses (small bruises)
- spontaneous muscosal bleeding (GI, urogenital, oral/nasal)
- surgical bleeding
13
Q
what is diagnosis of primary hemostasis
A
- platelet count
- platelet function tests
- VWF level (most common)
14
Q
what is secondary hemostasis
A
- formation of fibrin that crosslinks the primary platelet plug
- fibrinogen (factor I) converted to fibrin by thrombin (factor II)
- stable clot
- coagulation factors
- sequentially active/change other factors in a highly organized process
15
Q
what are coagulation factors
A
- proteins (produced in liver; factors III and VIII - endothelium)
- enzymatic and non-enzymatic
- some circulate in inactive form, need to be activated (by other factors; factors II, VII, IX, X - activated by VK)
16
Q
what is the cell based model of hemostasis
A
- overlapping phases takes place on different cell surfaces
- initiation
- amplification
- propagation
- starts with exposure of tissue factor
17
Q
what is tissue factor (TF)
A
- factor II
- most important factor in initiation of secondary hemostasis
- inactive in intravascular space, active in cytoplasm and extracellular domains
- secondary hemostasus gets activated when TF gets exposed from endothelial damage
18
Q
what phase in TF
A
initiation phase
19
Q
what phases are on the activated platelet surface
A
- amplification
- propagation
20
Q
what is the phospholipid bilayer of platelets
A
- phophatidylserine (PS) and phosphatidylethanolamine (PE) localized to the inner membrane surface
- PS and PE flip to outer surface with platelet activation
21
Q
what enzymes flip PS and PE to the outer surface and scramble them
A
- floppase
- flippase
- scramblase
22
Q
what is the initiation phase of hemostasis
cell based model
A
- exposure of tissue factor
- trace thrombin
23
Q
what is the amplification phase of hemostasis
cell based model
A
- thrombibn travels to platelet
- activates more factors
- activates and attracts more platelets
24
Q
what is the propagation phase of hemostasis
cell based model
A
- thrombin converts fibrinogen to fibrin
25
what is secondary hemostasis cascade model
* two arms of cascade (extrinsic, intrinsic, common pathway)
* operate independently
* redundant
26
what arm of the cascade model is prothrombin time (PT)
extrinsic
27
what arm of the cascade model is activated partial thromboplastin time (aPTT)
intrinsic
28
what does the cascade model test for
time (sec) for blood to go from fluid to clot
29
what are clinical signs of bleeding in secondary hemostasis
* body cavities (thoracic and abdominal)
* joints
* brain
* muscle
* subcutaneous tissue
30
what are tests of secondary hemostasis
* PT
* aPTT
* activated clotting time (ACT)
* individual factor levels
31
what is the termination phase
* endogenous antithrombotic elements
* regulation of hemostasis
* contains hemostasis to a localize area
32
what is used to deactivate a clot
* tissue factor pathway inhibitor
* antithrombin
* thrombomodulin
* protein C
33
what is fibrnolysis
uses plasmin to turn fibrin to fibrin degradation products
34
what does the circulatory system do
* mediates movements of all body fluids
* regulates body temp and distribution of hormones and leukocytes
35
what do arteries do
transport oxygen and nutrients to tissues
36
what do veins do
transport of CO2 and metabolic waste from tissues
37
what are the two functional components of the circulatory system
* blood vascular system
* lymph vascular system
38
what is the blood vascular system organized into
* heart
* arteries
* arterioles
* capillaries
* venules
* veins
39
this circuit of ___ ___ sustains the blood flow maintained by the heart
blood vessels
40
what does the arterial system provide
a distribution network for capillaries
| interchange of gases and metabolites between tissues and blood
41
what does the venus system do
returns blood from the capillaries to the heart
42
what is endothelium
flat epithelium in blood vessels
43
what is the tunica intima
inner lining made of single layer of endothelium supported by basement membrane and collagenous tissue
44
what is the tunica media
intermediate muscular layer
45
what is the tunica externa/adventitia
outer supporting tissue layer
46
what are companion vessels
artery traveling with vein because they supply the same body region and lie next to each other
47
what structural component is not in the vein
internal elastic layer in tunica intima
48
what do arteries look like
thick and have contractile muscular walls
49
____ permit change in vessel size in response to ____ ____ change and allow artery to absorb the pressure
elastic; blood pressure
50
what gives an artery the ability to change in size actively
contractility
51
what induces vasoconstriction
arterial smooth muscle contract and contrists artery
52
what is vasodilation
when smooth muscle relax to increase artery diameter
53
what does the venous system look like
* larger in diamter than arteries
* thinner walls than arteries because blood pressure is lower
54
what is less prominent in the venous system
elastic and muscular components
55
what is reveral in blood flow prevented by
valves in medium sized veins
56
where is a major part of the total blood volume contained
within the venous system
57
what is microcirculation
regulates exchange of gases, fluids, nutrients and metabolic waste
58
where does exhange occur
in capillaries that have extremely thin wall which lack a tunica media and form interconnected networks
59
blood flow is slow so there is sufficient time for ____ or ____ ____
diffusion or active transport
60
what are the 3 types of capillary endothelium
1. continuous - uninterrupted lining
2. fenstrated - contains pores/fenstrations
3. discontinous-
61
what are endothelial cells
flat polygonal cells interconnected by junctional complexes
62
what do endothelial cells act as
permeability barrier
63
what do endothelial cells synthesize
* extracellular matrix components for basement membrane maintenance
* products regulating blood coagulation, thrombosis and the balance between vascoconstriction/vasodilation
64
what do endothelial cells regulate
acute and chronic inflammatory responses through the expression of cell adhesion molecules and immune mediators
65
endothelial cell function is _______-dependent
compartment
66
what is the function of the nervous tissue
to recieve external and internal stimuli which are then analyzed and integrated to produce appropriate and coordinated responses
67
what is the nervous tissue composed of
network of neurons which constitute most sensory receptors, the conducting pathways, and sites of integration and analysis
68
what is the function of the neuron supported by
glial cells
69
the functions of the nervous system depend on the ____ of neurons
excitability
70
what does excitability involve
a change in membrane permeability in reponse to appropriate stimuli and the plasma membrane becomes depolarized inducing action potential which then spread along the plasma membrane
71
where are action potentials conducted
along the axon to influence other neurons/target organs
72
what are axons commonly reffered to as
nerve fibers
73
axons in the CNS are surrounded by ____ while in the PNS they are enclosed by _____ ___
oligodendrocytes; Schwann cells
74
small diameter axons are enveloped by the cytoplasm of
Schwann cells (non-myelinated nerves)
75
large diameter fibers are wrapped by cocentric layers of
schwann cell plasma membrane forming a myelin sheath (myelinated nerves)
76
what are myelinated nerves comprised of
fascicles
77
what are fasicles
bundles of funiculus that are group of axons
78
what are bundles of fascicles bounded by
epineurium
79
what is the CT called that surrounds each myelinated nerve fiber
endoneurium
80
what are fascicles bound by
perineurium
81
what is the neurovascular bundle
* consists of the binding of blood vessels and nerves with CT
* risk during surgery
