Haemostasis medium

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Questions and Answers

What is the role of von Willebrand factor in hemostasis?

It inhibits platelet activation.

It converts fibrinogen to fibrin.

It stabilizes the platelet plug. (correct)

It promotes blood vessel dilation.

Which chemical is released by platelets to attract more platelets during plug formation?

Thrombin

Adenosine diphosphate (ADP) (correct)

Collagen

Fibrinogen

What is the typical duration for primary hemostasis to occur?

8-10 minutes

3-5 minutes

2-7 minutes (correct)

1-3 minutes

Which condition is associated with prolonged bleeding time?

Thrombocytopaenia Signup and view all the answers

What components make up a clot during secondary hemostasis?

Platelets, red/white blood cells, and fibrin Signup and view all the answers

What is the main pathway that activates the coagulation cascade?

Extrinsic pathway Signup and view all the answers

Fibrin is formed from which precursor during clot formation?

Fibrinogen Signup and view all the answers

How does the fibrin mesh stabilize the platelet plug?

By creating a structural framework around the plug Signup and view all the answers

What process converts plasminogen into plasmin within a clot?

Thrombin activation Signup and view all the answers

What triggers the extrinsic pathway of coagulation?

Release of tissue factor from damaged endothelial cells Signup and view all the answers

What is a common consequence of increased fibrinolysis in the body?

Decreased blood clotting Signup and view all the answers

Which factor is involved in the conversion of factor VII to its activated form?

Tissue factor Signup and view all the answers

What role does thrombin-activated fibrinolysis inhibitor (TAFI) play in clot management?

Stabilizes clots Signup and view all the answers

What is the normal range for Prothrombin Time (PT)?

11-16 seconds Signup and view all the answers

What condition is associated with depressed fibrinolysis?

Antiphospholipid syndrome Signup and view all the answers

Which factor initiates the intrinsic pathway of coagulation?

Factor XII Signup and view all the answers

What is a potential outcome of the contraction of approximately 90% of the initial clot volume?

Healing of the injured vessel Signup and view all the answers

What is the primary difference between the intrinsic and extrinsic pathways?

Intrinsic is initiated by factors inside the blood vessel Signup and view all the answers

At what point do the intrinsic and extrinsic pathways converge?

At factor X Signup and view all the answers

Which factor acts on fibrin strands during the common pathway?

Factor XIII Signup and view all the answers

What is the normal range for Activated Partial Thromboplastin Time (aPTT)?

23-35 seconds Signup and view all the answers

What is the role of factor VIIa in the extrinsic pathway?

To activate factor X into factor Xa Signup and view all the answers

Damage to which structure primarily triggers the extrinsic pathway?

Endothelial cells Signup and view all the answers

What is the primary purpose of haemostasis?

To stop bleeding when a blood vessel is damaged Signup and view all the answers

What is a common sign indicating the body's prioritization of blood supply to the brain during severe conditions?

Blue lips and fingernails Signup and view all the answers

Which physiological response occurs first in primary haemostasis?

Vasoconstriction Signup and view all the answers

Which of the following best describes the process that occurs at a cellular level during haemostasis?

Coagulation and platelet activation Signup and view all the answers

What can be a consequence of losing more than 20% of blood volume?

Hypovolemic shock Signup and view all the answers

In response to injury, what do platelets release to facilitate vasoconstriction?

Serotonin and thromboxanes Signup and view all the answers

Which of the following symptoms might indicate severe blood loss and the body shutting down?

Weak pulse Signup and view all the answers

Why is maintaining haemostasis particularly important for young children and the elderly?

They are more vulnerable to consequences of rapid blood loss Signup and view all the answers

What is the role of platelets in primary haemostasis?

To form a platelet plug at the injury site Signup and view all the answers

What happens after blood pools into dental sockets post-extraction?

Pressure usually stops the bleeding within minutes Signup and view all the answers

What condition may result from significant blood loss requiring possibly a blood transfusion?

Anaemia Signup and view all the answers

Which of the following describes a minor loss of blood?

Small cuts or injuries Signup and view all the answers

Which of the following is NOT involved in the vasoconstriction process during primary haemostasis?

Red blood cells Signup and view all the answers

What physiological mechanisms does the body utilize to maintain blood volume and cells?

Homeostatic mechanisms Signup and view all the answers

What is primarily released by damaged blood vessels to mediate vasoconstriction?

Endothelins Signup and view all the answers

Which symptom is NOT associated with moderate blood loss?

Severe pain Signup and view all the answers

During the process of coagulation in secondary haemostasis, what is primarily formed?

Fibrin mesh Signup and view all the answers

What role do clotting factors play in haemostasis?

They facilitate coagulation processes Signup and view all the answers

A patient presenting with confusion, weakness, and little or no urine output is likely experiencing what?

Late-stage shock Signup and view all the answers

What is primarily affected by rapid blood loss?

The nourishment of organs Signup and view all the answers

Study Notes

Haemostasis

The process that stops bleeding when a blood vessel is damaged.
Involves three stages:
- Vasoconstriction
- Platelet plug formation
- Coagulation

Primary Haemostasis

Involves vasoconstriction and platelet plug formation.
Vasoconstriction:
- Blood vessels constrict, reducing blood flow.
- Mediated by serotonin, thromboxanes, and endothelins.
Platelet Plug Formation:
- Platelets adhere to damaged blood vessel walls through von Willebrand factor.
- Platelets release ADP, attracting more platelets, forming a plug.

Coagulation (Secondary Haemostasis)

Complex process, involving a cascade of clotting factors to stabilize the platelet plug with a fibrin mesh.
Fibrin is formed from soluble fibrinogen.

Clotting Cascade

A series of reactions involving clotting factors, leading to the formation of fibrin.
Two main pathways:
- Extrinsic pathway (Tissue factor pathway)
- Intrinsic pathway (Contact pathway)
Both pathways converge into a common pathway.

Extrinsic Pathway

Triggered by the release of tissue factor (factor III) from damaged endothelial cells.
Tissue factor activates factor VII into factor VIIa.
Factor VIIa activates factor X into factor Xa.
Measured by Prothrombin Time (PT).

Intrinsic Pathway

Triggered by blood coming into contact with collagen fibers in the broken blood vessel wall.
Initiated by factor XII (serine protease), which becomes factor XIIa after exposure to endothelial collagen.
Ends with the common pathway.
Measured by Activated Partial Thromboplastin Time (aPTT).

Common Pathway

Begins at factor X, which is activated into factor Xa.
Factor Xa converts prothrombin into thrombin.
Thrombin converts fibrinogen into fibrin.
Fibrin forms a mesh that stabilizes the platelet plug.

Fibrinolysis

The breakdown of the clot by plasmin.
Plasminogen, trapped within the clot, is converted to plasmin by activators released by damaged cells.
Plasmin breaks down fibrin.
Abnormal fibrinolysis can lead to bleeding disorders or thrombosis.

Relevance to Dental Hygienists/Therapists

Understanding haemostasis is essential for managing bleeding after procedures, such as extractions.
Knowledge of clotting factors and their inhibitors is important for patient care and drug interactions.
Consideration should be given to patients with haemostatic issues, particularly those with bleeding disorders or on anti-platelet medication.

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Description

Explore the essential processes involved in haemostasis, including primary and secondary haemostasis. This quiz covers vasoconstriction, platelet plug formation, and the clotting cascade, detailing the steps taken to prevent excessive bleeding after vascular injury.