Bleeding, Anticoagulation and the Cascade Pathway

Running head: BLEEDING, ANTICOAGULATION AND THE CASCADE PATHWAY
Bleeding, anticoagulation and the cascade pathway
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BLEEDING, ANTICOAGULATION AND THE CASCADE PATHWAY
Table of Contents
Introduction:...............................................................................................................................2
The mechanism of bleeding:......................................................................................................2
Overview of the coagulation system:.........................................................................................3
The cascade pathway:................................................................................................................5
Anti-coagulative Drugs and types:.............................................................................................7
Vitamin K antagonists:...........................................................................................................7
Non-VKA Oral Anticoagulants (NOACs):..........................................................................11
Other anticoagulants:...........................................................................................................13
Conclusion:..............................................................................................................................15
References:...............................................................................................................................16

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BLEEDING, ANTICOAGULATION AND THE CASCADE PATHWAY
Introduction:
Bleeding and coagulation is one of the various different metabolic procedures of
human body, and alike the other human metabolic processes, this particular procedure is also
critically associated with an intricate genetic network. Elaborating more on the process of
bleeding, it is also known as haemorrhage, a process in which there is loss of blood from the
circulatory system. Bleeding or haemorrhage can occur facilitated by many causes, ranging
from small cuts, bruises and abrasions, to grave injuries and amputation (1). Bleeding is a
normal physiological procedure in human body which is immediately followed by the process
of coagulation. Coagulation on the other hand is the process in which the blood clot is formed
at the site of bleeding. This phase is also known as the secondary hemostasis, as is forms the
second stage of the process of arresting blood from any ruptured vessel. There are various
factors that can complicate of blood clot formation in the human body, which in turn leads to
a complicated and difficult to treat complications, further complicating the recovery
procedure (2). This paper will discuss in detail the physiological process of bleeding in the
human body, overview of the coagulation system, the cascade pathway, and a thorough and
detailed discussion on the Anticoagulative Drugs and types, such as Vitamin K antagonists
(warfarin, coumarin), Non-VKA Oral Anticoagulants (NOACs), aspirin, heparins etc.
The mechanism of bleeding:
Discussing the physiological mechanism associated with bleeding, there is an intricate
genetic network that guides and directs the process. Bleeding or haemorrhage, can be internal
or external and can be mediated or facilitated via a variety of reasons. The blood loss can
occur from any part of the human body; in case of internal bleeding, the blood is leaked or
released through a damaged blood vessel or organ. And on the other hand, the external
bleeding which is facilitated by a break or tear in the skin, through which the blood is

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BLEEDING, ANTICOAGULATION AND THE CASCADE PATHWAY
released or lost. An important contrast between the two mechanisms of bleeding is the fact
that in case of internal bleeding the blood is released inside the body in the internal cavities
and in case of external bleeding the blood is being lost outside the body (1). A very common
type of bleeding is known as the traumatic bleeding, which is directly caused by abrasions
that do not involve penetration below the skin, hematoma, lacerations or incisions, puncture
wounds that are generated from sharp objects such as needles or knives, crushing injuries,
and lastly, gunshot wounds. The medical conditions also are noted to cause bleeding in the
human body due to conditions such as haemophilia, leukemia, liver disorders, menorrhagia
which in turn causes uncontrolled or prolonged menstrual bleeding, thrombocytopenia which
in turn causes low blood platelet count, vitamin K deficiency, brain, trauma, bowel
obstruction, congestive heart failure (CHF), lung cancer, acute bronchitis, severe
hypothermia, and endometriosis (3).
Overview of the coagulation system:
Coagulation is the immediate immune response of the body to the process of bleeding,
and is mediated by the first and second line of immune defence of the body. The procedure is
maintained or controlled by the platelet mediated primary haemostasis. The process of the
coagulation is facilitated by the formation of the platelet plug, which in turn marks the initial
occlusion of the vascular lesion, the contributing factor to the bleeding (4). This series of
actions are closely riveted by the activation of the coagulation system, facilitated in response
to the rupture of the endothelium and the exposure of blood to the extravascular tissues of the
body. Elaborating more on the procedure of the primary haemostasis, the events are triggered
by the damaged vascular wall which is facilitated when the sub-endothelial tissues are
exposed to the blood after the injury. This phenomenon is followed by a multitude of
coordinated interactions occurring amongst the different tissue components, plasma proteins,
and receptors on platelets which in turn facilitates the process of initial sealing of the