Clotting

Question 1

Overview of blood clotting

Answer 1

1) Damage to blood vessel
2) Vasoconstriction to reduce blood flow
3) Thrombocytes attach to wound (Plug formation - release vasoconstrictors for further vasoconstriction)
4) Clotting commences formation of fibrinogen net (Thrombin system)
5) Clot retraction to from scab
6) Clot breakdown

Question 2

Describe the damage site?

Answer 2

• Walls of blood are usually very smooth

- Damage to vessels creates rough surfaces in lumen which thrombocytes (platelets) stick to

Question 3

What happens immediately after damage?

Answer 3

Walls of the blood vessels constrict

Question 4

Describe platelets plugging

Answer 4

• Thrombocytes stick to the damaged area and attract more thrombocytes creating a plug
• For small tares in capillaries this is enough to stop bleeding

Question 5

Describe vasoconstrictions

Answer 5

• Thrrombocytes release vasoconstrictors that make the walls constrict more and for a longer time, further reducing blood flow to the damaged site

Question 6

Describe the clotting of blood

Answer 6

• forms over the site of a wound to stop the bleeding
• if a clot forms inside a blood vessel it forms a thrombus
• if a thrombus breaks loose it can lodge in a vital blood vessel in brain/heart and cause a stroke/heart attack

Question 7

Describe the thrombin system

Answer 7

1) Following damage to a blood vessel, blood platelets and the injured cells release thromboplastin
2) Thromboplastin interacts with CA + prothhrombin (an inactive plasma protein) to form thombin
3) Thrombin converts finbrinagen (inactive plastic protein) to long stretchy fibres of fibrin
4) The fibrin fibres form a mesh at the site of the wound, which traps platelets and blood cells
5) Within a few minutes, the clot starts to contract which pushes the edges of the broken blood vessel together

Question 8

Summary of thrombin system

Answer 8

• Thrombin + fibrinogen = fibrin

- Fibrin + blood vessels = clot

Question 9

Describe clot regeneration

Answer 9

• The threads in the clots contract, pulling the damaged vessels apart
• The fluid in the clot (serum) is forced out, drying the clot
• Serum= yellow, clear liquid that comes from the clot