L14 - haemostasis Flashcards

1
Q

haemostasis(HMS)meaning

A

stopping bleeding from damaged blood vessels

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2
Q

thrombosis

(TMB) meaning

A

clot formation in a blood vessel

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3
Q

how are blood components involved in hms and tmb

A

they work together to drive hms and forms tmb (clots)

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4
Q

how are tmb formation dangerous in some situation

A

can block major blood vessels and cause tissue ischaemia, leading to heart attacks, stroke

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5
Q

stages of HMS

A
  1. vasocon of vessel wall to restrict blood flow
  2. activation of platelets and formation of primary haemostatic plug
  3. activation of coagulation, fibrin formation and clot retraction. also makes secondary haemostatic plug
  4. fibrinolysis - using plasmin to break down blood clots after the tissue repair
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6
Q

how does vasocon happen in stage 1

A
  1. molecules released from injured cells
    - 2. molecules also released from platelets
  2. neural signals from pain receptors
    - reflex response
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7
Q

stage 2 -features of platelets

A

-small
-biconvex
-no nucleus
lifespan of 8-10 days
-internal membrane network
lots of granule s
-plasma membrane contained receptors to respond to damage
-organised cytoskeleton

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8
Q

stage 2- how can platelets be activated and what signals act upon on that

A
  • acitvated by different surface receptors

- signals are soluble activatory and vessel wall activatory signals

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9
Q

what happens after platelet activation

A

-changes shape
-secretes granules
and become sticky

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10
Q

why does changing shape help

A
  • plugs damage to the vessel
  • makes other platelets stick together
  • driven by cytoskeletion
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11
Q

what do platelets secrete

A
  • dense granules

- alpha granules

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12
Q

why does platelets secretion helps

A
  • activates platelets and cogaulation casade
    -repairs vessel wall and tissue
    -
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13
Q

how does platelets become sticky

A
  • integrin activated and then bind to fibronogen

- then other platelets bind to the fibrinogen

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14
Q

how is primary haemostatic plug formed

A
  • Von B factor released and sticks to the wall
  • the platelets sticks to the VB factor and relased granules to activate more platelets
  • the fibrinogen helps the platelets aggregation, forming the plug
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15
Q

stage 3 - how is secondary haemostatic plug

A

the fibrinogen is solube and becomes insoluble fibrin mesh through thrombin (FXIII AND FXIIIa)

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16
Q

how is thrombin generated

A

by cogagulation casade involving lot of factors

    1. precursor factors becomes active factors
      1. each step in the casade increases the signal
17
Q

stage 4 - how is fibrin clot broken down

A
  • ## plasmainogen -> plasmin by fibrin bound protease -> degrages fibrin
18
Q

why is fibrinolysis helpful

A

limit the process to the sit of injury

and prevent excessive thrombin growth