anticoagulation

Question 1

what is the role of prostacyclin?

Answer 1

released by endothelial layer of blood vessels, to stop the sticking of platelets to the blood vessel wall

Question 2

what is the role of nitric oxide gas in blood vessels?

Answer 2

it is released by endothelial layer of blood vessels to prevent sticking of platelets to the blood vessel wall and helps blood pressure regulation.

Question 3

what is the action of warfarin?

Answer 3

it is a vitamin K antagonist

inhibits vitamin K reductase which is needed by vitamin K to turn inactive prothrombin into thrombin.

Question 4

what is a DOAC?

Answer 4

an oral thrombin inhibitor (thrombin is the enzyme that converts fibrinogen into fibrin)

Question 5

why is the disadvantage of DOACs compared to warfarin?

Answer 5

DOACs cannot be reversed, warfarin can be reversed by taking vitamin K

Question 6

what is the role of heparins?

Answer 6

as warfarin takes a few days to take effect, , enoxaparin (a heparin) Is taken until it takes effect.

Question 7

why are heparins like enoxaparin not taken in long term?

Answer 7

they are uncomfortable to inject and taking enoxaparin every day would lead to platelet depletion

Question 8

where is arachidonic acid found?

Answer 8

in all cell membranes, it is chopped out of the cell membrane when cell is excited.

Question 9

what is the role of arachidonic acid?

Answer 9

it is converted by the COX enzyme into prostaglandins.

Question 10

what does prostaglandins do?

Answer 10

cause constriction of the airways

Question 11

what does prostacyclins do?

Answer 11

in blood vessel endothelial cells, they are antiplatlets and vasodilators 3

Question 12

what does thromboxane do?

Answer 12

in platelets, it increases aggregation

Question 13

what does nitric oxide do?

Answer 13

it is a gas that is released by the endothelial cells of the blood vessels and they help with blood pressure regulation and prevent platelets sticking to the blood vessel wall by increasing platelet cGMP

Question 14

what are the steps in the arachidonic acid pathway?

Answer 14

arachidonic acid in all cell membranes > free arachidonic acid > endoperoxides > prostaglandins > prostacyclins / thromboxane

Question 15

what is the action of low dose aspirin?

Answer 15

it is a COX inhibitor.
it prevents the reaction of free arachidonic acid to endoperoxides.
so stops prostacyclin formation and thromboxane formation.
this is bad as you want a low level of thromboxane but you don’t want prostacyclin levels to deplete.

Question 16

how does the cell regulate the prostacyclin levels when low dose aspirin is used?

Answer 16

both thromboxane and prostacyclin are not being production become there is no COX enzyme.
but if the cell has a nucleus, the COX enzyme will be coded for and made by protein synthesis within a few hours.
thromboxane production is in the platelets which do not have a nucleus, so COX enzyme will never be reproduced .
the prostacyclins are produced by the endothelial cells of blood vessels which have a nucleus, so the COX will be reproduced and the body can maintain a good level of prostacyclins whilst keeping the levels of thromboxane down.