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Principles of Disease > Circulation 1 > Flashcards

Circulation 1 Flashcards

1
Q

Describe the structure of an artery.

A
  • Endothelial cell lines lumen.
  • Endothelial cells make basal lamina to sit on.
  • All around the basal lamina are smooth muscle cells.
  • -Around smooth muscle cells are interstitial collagen fibres.
  • Inside the lumen contains Red blood cells, white blood cells, platelets (white in colour, very small)

look at notes for diagram

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2
Q

What are platelets not normally exposed to?

A

Interstitial collagen fibres around the vessel

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3
Q

What does the lumen also contain?

A

Plasma:

  • water, numerous proteins and other molecules
  • remove RBC, WBC, Platelets are you are left with plasma
  • contains clotting factors
  • serum is plasma without clotting factors
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4
Q

What is serum?

A

plasma without clotting factors

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5
Q

Where are clotting factors mainly produced?

A

Liver, but also by endothelial cells

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6
Q

How are clotting factors named?

A

a Roman numeral eg Factor VIII

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7
Q

What are clotting factors described and what do they do?

A
  • They are an amplification system/clotting cascade, resulting in thrombin production from prothrombin
  • thrombin, in turn converts Soluble Fibrinogen into insoluble fibrin strands
  • Fibrin forms a mesh of strands
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8
Q

What is meant by initial damage?

A

trauma.

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9
Q

What does initial damage lead to?

A
  1. Exposure of interstitial collagens

2. Exposure of a molecule called Tissue Factor (TF)

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10
Q

What does trauma result in?

A
  • Defects in vessels.
  • Blood leaks out and serum comes into contact with interstitial collagen fibres.
  • Plasma clotting factors can now be activated as they contact interstital collagens
  • Tissue factor is also released from smooth muscle cells.
  • Tissue factor can now bind to a particular clotting factor and initiate the clotting cascade.
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11
Q

How are clotting factors activated?

A
  • Blood leaks out and serum comes into contact with interstitial collagen fibres.
  • Plasma clotting factors can now be activated as they contact interstital collagens
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12
Q

What are the structure of many clotting factors?

A
  • Many clotting factors are serine proteases - = they have a serine amino acid in them and they cleave other clotting factors to form the active molecule
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13
Q

What are platelets and where are they produced?

A
  • Produced in bone marrow From cell called a megakaryocyte
  • Megakaryocyte = Large cell with many nuclei
  • Bud off as fragments from cytoplasmic extensions
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14
Q

Why are megakaryocytes large cells with many nuclei?

A

Undergoes nuclear division but not cell division so get huge cell with many nuclei

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15
Q

What is the function of platelets?

A
  • Trauma to vessel  Exposure of platelets to interstitial collagen
  • Platelets adhere together try to form bridge to close gap
  • Coagulation:
    • Solidification of blood which is:
    • 2 types: Thrombus formation and clot formation
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16
Q

What is thrombus formation/thrombosis?

A
  • Occurs in flowing blood and stops bleeding from gaps in vessels
  • A pure thrombus is pale cream coloured
17
Q

Why does thrombus of platelets and fibrin occur in flowing blood?

A
  • Platelets have molecules on their surfaces which allow adherence to interstitial collagen, even when blood is flowing past them – the clotting cascade deposits Factor VIII which enhances this further
18
Q

How to remove thrombus?

A
  • Fibrinolytic system:
  • A blood protein called Plasminogen converts to plasmin, and plasmin cuts up fibrin into smaller fragments, as a way of removing fibrin (in both clots and thrombi).
19
Q

What is the fibrinolytic system Called in a thrombus?

A

-In a thrombus this is sometimes called thrombolysis

20
Q

What is the fibrinolytic system normally in balance with?

A

-The clotting system.

21
Q

What Is the function of the finbrinolytic system?

A

Plasmin generation, at the site of injury, limits the extent of the evolving thrombus.

22
Q

What is clot formation?

A
  • Think of black pudding. Blood leaks off a vessel and becomes stationary/stagnant.
  • Within the stagnant blood, sitting next to the interstitial collagen, the clotting cascade is activated.
23
Q

What is haemostats?

A

stopping bleeding in normal skin with wound

24
Q

Describe the beginning stages of the activaiton of the clotting system, in a clot.

A
  • Vessel in the skin is surrounded by collagen.
  • Trauma i.e. cut to skin disrupts one side of the vessel.
  • Blood, including red blood cells, leaks out.
25
Q

Describe the process of when clots do not work perfectly

A
  • The clotting system is activated by Collagen and by the Stagnant Blood, forming a clot.
  • But this may not work perfectly and the wound may continue to bleed.
  • The vessel vasoconstricts to decrease blood loss.
  • A platelet and fibrin thrombus forms to bridge the gap between the ends of the vessel adjacent to flowing blood.
  • The skin now stops bleeding- haemostasis has been achieved.
26
Q

What are the advantages of any wound due to trauma?

A
  • Vasoconstriction helps reduce bleeding
  • Clot formation occurs in space around vessel and may fill void of wounded tissue
  • Thrombus forms in flowing blood and stops bleeding from gaps in vessels
27
Q

What can grow in the area of wound?

A
  • New vessels can grow called granulation tissue.

- The capillaries that grow in granulation tissue can oxygenate the area of wound and keep it alive.

28
Q

What physiological mechanisms is thrombosis and clotting normal in?

A

Wound healing and stopping bleeding during menstruation.

29
Q

What does a thrombus consist of?

A

consists of platelets, red blood cells and a mesh like network of fibrin strands

30
Q

What does a clot consist of?

A

A network of fibrin strands and platelets, red blood cells.

31
Q

What does thrombus do?

A

Stops bleeding from gaps in vessels

Principles of Disease (53 decks)

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