Blood - Chapter 17-6 Platelets, disc-shaped structures formed from megakaryocytes, in the clotting process

Platelet Functions

1. The Release of Chemicals Important to the Clotting Process 2. The Formation of a Temporary Patch in the Walls of Damaged Blood Vessels 3. Active Contraction after Clot Formation Has Occurred

thrombocytopenia

An abnormally low platelet count (80,000/^LIL or less) is known as _____________. _______________ generally indicates excessive platelet de struction or inadequate platelet production. Signs include bleeding along the digestive tract, within the skin, and occasionally inside the CNS.

nonmammalian vertebrate blood

CHECKPOINT Explain the difference between platelets and thrombocytes. Platelets are non-nucleated cell fragments in , whereas thrombocytes are nucleated platelets in ______________.

mammal blood

CHECKPOINT Explain the difference between platelets and thrombocytes. Platelets are non-nucleated cell fragments in , whereas thrombocytes are nucleated platelets in nonmammalian vertebrate blood.

three primary functions of platelets

CHECKPOINT List the _______________. 1. Platelets release chemicals important to the clotting process, 2. form a temporary patch in the walls of damaged blood vessels, and 3. contract after a clot has formed.

Thrombocytopoiesis

CHECKPOINT ___________________ is the term for platelet production.

thrombocytosis

In ____________, platelet counts can exceed l,000,000//xL. ______________ generally results from accelerated platelet formation in response to infection, inflammation, or cancer.

Active Contraction after Clot Formation Has Occurred

Platelet Functions 1. The Release of Chemicals Important to the Clotting Process 2. The Formation of a Temporary Patch in the Walls of Damaged Blood Vessels 3. _____________________________

The Formation of a Temporary Patch in the Walls of Damaged Blood Vessels

Platelet Functions 1. The Release of Chemicals Important to the Clotting Process 2. _______________________________ 3. Active Contraction after Clot Formation Has Occurred

The Release of Chemicals Important to the Clotting Process

Platelet Functions 1. _____________________________ 2. The Formation of a Temporary Patch in the Walls of Damaged Blood Vessels 3. Active Contraction after Clot Formation Has Occurred

megakaryocytes

Platelet Production Normal bone marrow contains a number of _________ (meg-a-KAR-e-o-sits; mega-, big + karyon, nucleus + -cyte, cell), enormous cells (up to 160 /xm in diameter) with large nuclei.

thrombocytopoiesis

Platelet Production Platelet production, or ______________, occurs in the bone marrow.

thrombocyte-stimulating factor

Platelet Production Thrombopoietin (TPO), or ____________, a peptide hormone produced in the kid-neys (and perhaps other sites) that accelerates platelet formation and stimulates the production of megakaryocytes.

Interleukin-6

Platelet Production _______, a hormone that stimulates platelet formation

multi-CSF

Platelet Production ________, which stimulates platelet production by promoting the formation and growth of megakaryocytes.

Hormonal controls

Platelet Production _____________: a. Thrombopoietin (TPO) b. Interleukin-6 c. Multi-CSF

clotting system

Platelets are a major participant in a vascular__________ that also includes plasma proteins and the cells and tissues of the blood vessels.

thrombocytes

Platelets, or _________, are small, disk shaped clear cell fragments, which are derived from fragmentation of precursor megakaryocytes. - 2-3 µm in diameter - lifespan 5 to 9 days - continuously replaced. - circulates for 9-12 days before being removed by phagocytes, mainly in the spleen. - microliter of circulating blood contains 150,000-500,000 platelets; 350,000/^L is the average concentration. - 1/3 of the platelets in the body at any moment are held in the spleen and other vascular organs, rather than in the bloodstream. These reserves are mobilized during a circulatory crisis, such as severe bleeding - granules - thromboxanne* - ca++ -Calcium - P,D G F ( Plate Dirived Growth Factor) - Platelet clotting factors - Help in Hemostasis (prevent blood loss) *Thromboxane is a member of the family of lipids known as eicosanoids.

Platelets

_______ are flattened discs that appear round when viewed from above, and spindle shaped in section or in a blood smear.

Thrombocytes

_________ are cells that play a key role in blood clotting, aggregating with thrombin. _______ lack major organelles. _________ of nonmammalian vertebrates have a nucleus and resemble B lymphocytes

Megakaryocytes

_____________ are large, polyploid cells that reside in the bone marrow and produce platelets (also known as thrombocytes). Cell with a big nucleous.