L14 - haemostasis

Question 1

haemostasis(HMS)meaning

Answer 1

stopping bleeding from damaged blood vessels

Question 2

thrombosis

(TMB) meaning

Answer 2

clot formation in a blood vessel

Question 3

how are blood components involved in hms and tmb

Answer 3

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

Question 4

how are tmb formation dangerous in some situation

Answer 4

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

Question 5

stages of HMS

Answer 5

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

Question 6

how does vasocon happen in stage 1

Answer 6

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

Question 7

stage 2 -features of platelets

Answer 7

-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

Question 8

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

Answer 8

• acitvated by different surface receptors

- signals are soluble activatory and vessel wall activatory signals

Question 9

what happens after platelet activation

Answer 9

-changes shape
-secretes granules
and become sticky

Question 10

why does changing shape help

Answer 10

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

Question 11

what do platelets secrete

Answer 11

• dense granules

- alpha granules

Question 12

why does platelets secretion helps

Answer 12

• activates platelets and cogaulation casade
  -repairs vessel wall and tissue
  -

Question 13

how does platelets become sticky

Answer 13

• integrin activated and then bind to fibronogen

- then other platelets bind to the fibrinogen

Question 14

how is primary haemostatic plug formed

Answer 14

• 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

Question 15

stage 3 - how is secondary haemostatic plug

Answer 15

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

Question 16

how is thrombin generated

Answer 16

by cogagulation casade involving lot of factors

• 1. precursor factors becomes active factors
     
     2. each step in the casade increases the signal

Question 17

stage 4 - how is fibrin clot broken down

Answer 17

• ## plasmainogen -> plasmin by fibrin bound protease -> degrages fibrin

Question 18

why is fibrinolysis helpful

Answer 18

limit the process to the sit of injury

and prevent excessive thrombin growth