Author Question: How are platelets released into peripheral circulation from the bone marrow? a. Mature platelets ... (Read 37 times)

laurencescou

  • Hero Member
  • *****
  • Posts: 593
How are platelets released into peripheral circulation from the bone marrow?
 
  a. Mature platelets squeeze between sinusoid endothelial cells.
  b. Megakaryocyte cytoplasmic fragments extend through the endothelial cells, lining the sinusoids, into blood and then shed platelets.
  c. Platelets adhere to white cells and exit with them.
  d. Megakaryocytes exit the marrow with white cells and then platelets fragment off once they reach the blood.

Question 2

When platelets are activated, all of the following occur except:
 
  a. a-Granule contents are released.
  b. Smooth cytoplasmic membrane margins change to spiny projections.
  c. The prostaglandin (eicosanoid synthesis) pathway is activated.
  d. Adenosine diphosphate (ADP) release is inhibited.



bigcheese9

  • Sr. Member
  • ****
  • Posts: 333
Answer to Question 1

ANS: B
Cytoplasmic extensions elongate and pierce between the endothelial cells that line the marrow sinuses; then they extend into venous blood. These extensions release platelets once they enter blood. The cytoplasmic extensions are called proplatelet processes.

Answer to Question 2

ANS: D
When the platelet is activated, storage ADP is released from the platelet and then binds to its ligand on the platelet membrane, acting as an agonist. All the other changes listed do occur when the platelet is activated.



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
 

Did you know?

In 1835 it was discovered that a disease of silkworms known as muscardine could be transferred from one silkworm to another, and was caused by a fungus.

Did you know?

When intravenous medications are involved in adverse drug events, their harmful effects may occur more rapidly, and be more severe than errors with oral medications. This is due to the direct administration into the bloodstream.

Did you know?

Not getting enough sleep can greatly weaken the immune system. Lack of sleep makes you more likely to catch a cold, or more difficult to fight off an infection.

Did you know?

Bisphosphonates were first developed in the nineteenth century. They were first investigated for use in disorders of bone metabolism in the 1960s. They are now used clinically for the treatment of osteoporosis, Paget's disease, bone metastasis, multiple myeloma, and other conditions that feature bone fragility.

Did you know?

People who have myopia, or nearsightedness, are not able to see objects at a distance but only up close. It occurs when the cornea is either curved too steeply, the eye is too long, or both. This condition is progressive and worsens with time. More than 100 million people in the United States are nearsighted, but only 20% of those are born with the condition. Diet, eye exercise, drug therapy, and corrective lenses can all help manage nearsightedness.

For a complete list of videos, visit our video library