Platelets: Hemostasis - Video Tutorials & Practice Problems
Introduction to Platelets
Platelets: Hemostasis Example 1
Platelets are similar to erythrocytes in that both structures do not contain a _________________. Platelets are similar to leukocytes in that both their primary functions involve ________________ the body.
Plasma membrane; nourishing.
Plasma membrane; protecting.
Nucleus; nourishing.
Nucleus; protecting.
Overview of Hemostasis
Platelets: Hemostasis Example 2
Which physiological response causes a reduction in blood flow immediately after a blood vessel injury?
Migration of leukocytes to the site of the injury.
Platelet plug formation.
Vascular spasm.
Release of tissue plasminogen activator.
Vascular Spasm
Platelets: Hemostasis Example 3
Which of the following statements about vascular spasms is false?
It occurs when smooth muscle cells surrounding the blood vessel relax, increasing the vessel's diameter.
It can help reduce blood flow immediately after a blood vessel is damaged, thereby reducing blood loss.
It is the first step of hemostasis, directly preceding platelet plug formation.
It is initiated by chemicals released by damaged endothelial cells, smooth muscle, & activated platelets.
Platelet Plug Formation
Platelets: Hemostasis Example 4
Prostacyclin is a hormone that is normally active in the blood but becomes inactive when a blood vessel ruptures and hemostasis begins. Considering this, which of the following is the most likely function of prostacyclin?
Causes platelets to aggregate.
Prevents platelets from aggregating.
Activates vWF.
Initiates coagulation.
Coagulation (Blood Clotting)
Platelets: Hemostasis Example 5
Which of the following is the most likely outcome if platelets could not release aggregating agents?
Platelets would not be able to bind to collagen within damaged endothelial cells.
Too many platelets would aggregate at the site of the injury, causing blood clots that are too large.
Not enough platelets would aggregate at the site of the injury and an effective clot may not form.
There would be no effect.
How To Remember Important Coagulation Components
Which option correctly arranges/orders the components of the coagulation pathway?
Prothrombin Activator → Thrombin → Prothrombin → Fibrinogen → Fibrin.
Prothrombin Activator → Prothrombin → Thrombin → Fibrinogen → Fibrin.
Prothrombin → Prothrombin Activator → Thrombin → Fibrinogen → Fibrin.
Prothrombin Activator → Prothrombin → Thrombin → Fibrin → Fibrinogen.
Clot Retraction & Fibrinolysis
Platelets: Hemostasis Example 6
What would happen if plasminogen was activated before clot retraction?
Clot retraction would be completed even faster.
Fibrinolysis would occur too early & the healing process could be interrupted.
There would be no significant effect.
Do you want more practice?
- The following is a list of the phases involved in the process of hemostasis. 1. coagulation 2. fibrinolysis 3...
- Which of the following does not promote multiple steps in the clotting pathway? a. platelet phospholipids, b....
- Multiple Choice More than one choice may apply. A condition resulting from thrombocytopenia is a. thrombus...
- ___and ____ affect almost every aspect of the clotting process. (a) Calcium, vitamin K, (b) Calcium, vitami...
- Multiple Choice More than one choice may apply. Place the letters of these events in the order they occur dur...
- What is the difference between prothrombin and thrombin?
- a. Define fibrinolysis. b. What is the importance of this process?
- What contribution from the intrinsic and the extrinsic pathways is necessary for the common pathway to begin?
- a. How is clot overgrowth usually prevented? b. List two conditions that may lead to unnecessary (and undesira...
- Dehydration would (a) cause an increase in the hematocrit, (b) cause a decrease in the hematocrit, (c) hav...
- a. Define hemostasis. b. List the three major phases of coagulation. Explain what initiates each phase and wha...
- What is the role of blood in the stabilization and maintenance of body temperature?
- Why is aspirin sometimes prescribed for the prevention of vascular problems?
- A test for prothrombin time is used to identify deficiencies in the extrinsic clotting pathway; prothrombin ti...
- Almost half of our vitamin K is synthesized by bacteria that inhabit the large intestine. Based on this inform...
- Number the steps of hemostasis in order, putting 1 by the first event, 2 by the second, and so on. ____Th...
- How do the intrinsic/contact activation and extrinsic/tissue factor coagulation pathways differ? How are the...
- What are the overall goals of the common pathway of coagulation?
- Which of the following is not an anticlotting agent produced by endothelial cells?a. Prostacyclinb. Protein Cc...
- Tissue plasminogen activator, urokinase, and plasmin are important components of:a. coagulation.b. fibrinolysi...
- The anticoagulant drug warfarin primarily disrupts the extrinsic/tissue factor coagulation pathway. Explain wh...
- Cirrhosis of the liver often reduces production of many types of plasma proteins, including albumin and clotti...