Session 5 Lecture Notes

Question 1

What is the definition of thrombus?

Answer 1

The formation of a solid mass of blood within the circulatory system

Question 2

What are lines of Zahn?

Answer 2

Lines of the thrombus of different intensities - it varies depending on number of RBCs at a given time

Question 3

What are darker in colour - arterial or venous thrombi?

Answer 3

Venous because they have a higher cell content

Question 4

What is lysis of a thrombus and how does it take place?

Answer 4

Lysis = thrombus is broken down and vessel flow returns to normal
Plasmin breaks down the fibrin clot (via the fibrinolytic system)

Question 5

What is propagation of a thrombus?

In what direction (to or from the heart) does it travel in which vessels?

Answer 5

Progressive spread of the thrombus

It spreads towards the heart in veins and away in arteries

Question 6

What is organisation of thrombosis?

Answer 6

A reparative process where fibroblasts and capillaries replace the thrombus
However the vessel remains occluded and you don’t have normal blood flow

Question 7

What is recanalisation of a thrombus?

Answer 7

Following organisation of a thrombus (i.e. when fibroblasts and capillaries produce CT to replace the clot), a new vascular channel grows through the CT so some blood flow is established
Lumen is still much smaller than its original size

Question 8

What is the definition of an embolism?

What % are caused by thrombus?

Answer 8

The blockage of a blood vessel by solid, liquid or gas at a point distant from its origin
90% caused by thrombus

Question 9

If a systemic vein thrombus embolises where would it end up?

Answer 9

In the lungs (pulmonary embolism)

Question 10

If a thrombus formed in the LA or LV and embolised where would it go?

Answer 10

Out the aorta and into other arteries around the body

Question 11

If a carotid artery had a thombus that embolised where would this end up?

Answer 11

In the brain

Question 12

If an abdominal aorta had a thrombus that embolised where would this end up?

Answer 12

In the arteries of the legs

Question 13

What is a massive PE?

Answer 13

A 60% reduction in blood flow

Question 14

What is a major PE?

Answer 14

When medium sized vessels are blocked

Question 15

What is a minor PE?

Answer 15

When peripheral pulmonary arteries are blocked

Question 16

What is an iatrogenic embolism?

Answer 16

When something accidentally injected into the blood embolises

Question 17

What is a fat embolism and when does it usually occur?

Answer 17

It usually occurs following a long bone fracture when bone marrow containing fat is released into the bloodstream a

Question 18

What is haemostasis?

Answer 18

Haemostasis = the human body’s response to blood vessel injury and bleeding
It involves a coordinated effort between platelets and blood clotting factors to form a blood clot and prevent bleeding

Question 19

Explain the 3 stages of haemostasis

Answer 19

1. Platelets aggregate to injured vessel wall and form a clot
2. Thrombin cleaves fibrinogen to fibrin forming a more stable clot
3. Roughly 24 hours later the fibrin is broken down by plasmin (fibrolysis) and the degradation products are removed

Question 20

What bone marrow cells are responsible for platelet production?

Answer 20

Megakaryocytes

Question 21

What is the normal life span of platelets?

What is the normal life span of RBCs?

Answer 21

Platelets = 7-10 days
RBCs = 120 days

Question 22

When damaged tissue is exposed it reveals collagen. Platelets adhere to collagen via what receptor?

Answer 22

vWF receptor

Question 23

Where are clotting factors made?

Answer 23

In the liver

Question 24

What is exposed in tissue walls to activate factor 7?

Answer 24

Tissue factor

Question 25

What is Von Willebrand factor involved in?

Answer 25

Platelet adhesion to the vessel wall, platelet aggregation and it also carries factor 8

Question 26

What does plasmin break the fibrin clot down into?

Answer 26

D dimers

Question 27

Name 3 natural anticoagulants

Answer 27

Protein C
Protein S
Antithrombin

Question 28

Name two congenital coagulation factor disorders

Answer 28

1. Haemophilia 
Haemophilia A = deficiency in factor 8
Haemophilia B = deficiency in factor 9
2. Von Willebrand's disease (needed
for platelet adhesion and carries factor 8)

Question 29

Name some acquired coagulation factor disorders

Answer 29

1. Liver disease (as coagulation factors are produced in liver)
2. Vit K deficiency - needed for metabolism of some clotting factors
3. Anticoagulants such as warfarin inhibit Vit K

Question 30

What is the most common immune destruction cause of low platelet numbers?

Answer 30

Immune thrombocytopenia purpura

Autoantibodies are made against glycoproteins on platelet surface

Question 31

When do you start to see symptoms of thrombocytopenia?

Answer 31

When the platelet count is less than 30

You may see small bleeds into the skin and easy bruising