Lecture 4: Hemostasis Flashcards

1
Q

Hemostasis

A

Prevents blood loss from a broken blood vessel

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1
Q

Hemostasis

A

Prevents blood loss from a broken blood vessel

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2
Q

Hemostasis Involves 3 major steps

A
  1. Vascular spasm
    • Reduces blood flow through a damaged vessel
  2. Formation of a platelet plug
    • Platelets aggregate on contact with exposed collagen in
      damaged wall of the vessel
    • Platelets release ADP which causes surface of nearby circulating
      platelets to become sticky in order to adhere to first layer of
      aggregated platelets
  3. Blood coagulation (clotting)
    Transformation of blood from liquid into a solid gel
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3
Q

Platelets

A

cellular entities important for clotting

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4
Q

Thrombocytes
(AKA platelets)

A

Cell fragments shed from megakaryocytes
- Lack nuclei
- Have organelles and cytosolic enzymes for generating energy
and synthesizing secretory products
- High concentrations of actin and myosin
- Remain functional for an average of 10 days
- Removed from circulation by tissue macrophages

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5
Q

Do thrombocytes leave blood as WBCs do

A

NO:
- About ⅓ are stored in blood-filled spaces in spleen
- Released when needed by sympathetically induced splenic
contraction

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6
Q

Thrombopoietin

A

Hormone produced by liver increases number of megakaryocytes and therefore increases platelet production

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7
Q

What do platelets do?

A

thrombocytes are actually tiny cell fragments that circulate in blood and are essential for normal blood clotting.

When there is an injury and bleeding begins:
- platelets help stop bleeding by adhering to the injury site and
clumping together to form a temporary plug.
- They also release chemical signals that attract and promote
clumping of additional platelets and eventually become part of a
stable blood clot at the site of the injury that remains in place until
the injury heals.

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8
Q

High/ low platelet count

A

If you have a disease or condition that causes low platelets (thrombocytopenia) or dysfunction of platelets, you may be at an increased risk of excessive bleeding and bruising.

An excess of platelets (thrombocytosis) can cause excessive clotting.

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9
Q

Label these 4 images

A

A- RBCs and a platelet
B- RBC
C- RBC membrane
D- Platelet

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10
Q

Clot formation

A
  • In circulation platelets and plasma proteins allow the body to form clots - prevents bleeding out
  • Reinforces platelet plug and converts blood in the vicinity of vessel injury into a nonflowing gel
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11
Q

Abnormal blood clotting

A

Results from:
- Too much inflammation and inflammatory biomarkers in circulation
that act on the plasma proteins and platelets
- the platelets become hyperclottable and they hypercoagulate
= Clots = cause strokes and heart attacks

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12
Q

Abnormal Blood Clotting: hypercoagulation types

A
  1. Thrombus: Abnormal intravascular clot attached to a vessel wall
  2. Emboli: Freely floating clots
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13
Q
A

Plasma clot in a healthy person

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14
Q
A

plasma clot when inflammation is present e.g. diabetes

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15
Q

What happens when we have inflammation?

A
  • The circulating biomarkers in blood will also act on platelets
  • The platelets become hyper-activated and clump together- and also interact with red blood cells
16
Q
A
  • Sample from a person which had a stroke less than 2 hours
    before
  • The platelets are totally destroyed and are hyper-activated
  • Also see strange RBC (in B) = aerothotic red blood cell - cant carry
    O2 properly
  • This person had a thromboembolic stroke;
    Where the specific blood areas - the platelets and different plasma proteins (in C) form a clot in one vessel = stroke
17
Q

Abnormal blood clotting: bleeding

A

Thrombocytopenia
Hemophilia

18
Q

Thrombocytopenia

A

Insufficient number of platelets
Petechiae on the skin (purple blotches)

19
Q

Hemophilia

A

Excessive bleeding caused by deficiency of one of the factors in the clotting cascade

20
Q

complete blood count (CBC)

A
  • Determines how well blood system is functioning
  • is a group of tests that evaluate the cells that circulate in blood,
    including:
    red blood cells (RBCs)
    white blood cells (WBCs)
    platelets (PLTs).

The CBC can evaluate your overall health and detect a variety of diseases and conditions, such asinfections,anemiaandleukemia.
Blood cells are produced and mature primarily in thebone marrowand, under normal circumstances, are released into the bloodstream as needed.