Thrombosis, embolism and shock

Question 1

Briefly describe what happens in haemostasis when there is an injury to a vessel.

Answer 1

After the injury the arterioles constrict and expose the extracellular matrix which attracts platlets which aggregate and then become active. The active platelets cause release of chemokines, sending signals to attract more platelets to the site and form a platelet plug.

Question 2

The presence of which clotting factor catalyses the action of fibrinogen to fibrin?

Answer 2

Thrombin

Question 3

How do we limit coagulation to the site of an injury?

Answer 3

Anticoagulents ciculating in the blood. e.g. antithrombins and plasmin

Question 4

What affect does a high prothrombin time/INR have on clotting?

Answer 4

It reduces clotting

Question 5

What is thrombosis?

Answer 5

A blood clot in vessels leading to a lump/mass of blood constituents.

Question 6

What is the difference between a thrombus and an embolus?

Answer 6

Thrombus is a blood clot and an embolus is a piece of the blood clot that has broken free and is travelling through veins to somewhere other than the point of origin.

Question 7

What are the 3 factors that promote coagulation?

Answer 7

• Abnormalities of blood vessel wall
• Abnormalities of blood flow
• Abnormalities of the bloods constituents.

Question 8

Main locations where throbi can form

Answer 8

Heart, arteries, veins and capillaries

Question 9

What can cause venous thrombosis?

Answer 9

A change in the flow of blood fom inactivity.
Immobility due to loss of function/op recovery.
Direct compression of veins.

Question 10

3 things can happen to a thrombi, what?

Answer 10

1- can be broken down by fibrinolysis
2- converted into a scar by macrophages and fibroblasts, this narrows the lumen on the vessel.
3- the thrombi becomes detached and causes thromboembolism.

Question 11

What are the causes of emboli?

Answer 11

Thrombus, fat, gas, tumour, infections, amniotic fluid and foreign bodies.

Question 12

Arterial thromboembolism can cause what in the legs?

Answer 12

Acute ischaemia

Question 13

What is a tumour material emboli?

Answer 13

When a tumour penetrates blood vessels and parts break off to fom metastases

Question 14

In terms of an emboli what can happen if a uterus contracts very powerfully?

Answer 14

It can force amniotic fluid and squames from the infant into the veins of the mother to form an emboli.

Question 15

What is shock?

Answer 15

When the organs and tissues are not recieving enough blood and oxygen supply and allows waste roducts to build up.

Question 16

What are the clinical features of shock?

Answer 16

Low BP, tachycardia, really low or really high resps, low urine output, metabolic acidosis, hypoxia etc

Question 17

What is compensated shock?

Answer 17

Non progressive and the blood volume loss is 15-25%

Question 18

What is non-compensated shock?

Answer 18

Progressive and blood volume loss is over 25%

Question 19

What is irreversible shock?

Answer 19

Failure to restore circulation and there is critical organ damage

Question 20

What is hypovolaemic shock?

Answer 20

Haemorrage causes a sever amount of blood loss and the heart can’t pump enough around the body.

Question 21

What is cardiogenic shock?

Answer 21

When your heart is suddenly uable to pump enough blood arount the body often caused by acute heart attacks.

Question 22

What is septic shock?

Answer 22

When there is a significant drop in BP leadin to heart failure and failure of other organs. Caused by endooxins and infections.

Question 23

What is anaphylactic shock?

Answer 23

A severe form of an alleric reaction.

Question 24

What is neurogenic shock?

Answer 24

After damage to the CNS/spinal cord, low BP and slowed heart rate due to the disruption of autonomic pathways.

Question 25

How can obstructive shock occur?

Answer 25

Cardiac temponade
Tension pneumothorax
Massive pulmonary embolism causing obstruction of blood flow to the heart and other major organs.