Blood Clotting + Atherosclerosis

Question 1

Give two reasons for blood clotting.

Answer 1

• Limits blood loss

- Prevents entry of pathogens through open wounds

Question 2

Describe the blood clotting process (6)

Answer 2

• Platelets and damaged blood vessel tissue release thromboplastin.
  -Presence of calcium ions, protein factors and Vitamin K in blood plasma activates thromboplastin
• The enzyme catalyses conversion of prothrombin to thrombin
• Thrombin enzyme catalyses conversion of fibrinogen to fibrin
• Fibrin fibres form a mesh
• Traps red blood
  cells and platelets to form a blood clot

Question 3

What is prothrombin?

Answer 3

A soluble protein

Question 4

What are both thrombin and thromboplastin?

Answer 4

Enzymes

Question 5

What is fibrinogen?

Answer 5

A soluble globular protein

Question 6

What is fibrin?

Answer 6

Solid insoluble fibres - a fibrous protein

Question 7

What’s needed for thromboplastin to catalyse the reaction of prothrombin to thrombin? 3

Answer 7

• Calcium ions
• Vitamin K
• Protein factors

Question 8

What 3 diseases are caused by the formation of blood clots?

Answer 8

• Heart attack/myocardial infarction
• Stroke
• Deep Vein Thrombosis

Question 9

What are the symptoms of a heart attack? 3

Answer 9

• Pain in chest and upper body
• Shortness in breath
• Sweating

Question 10

How does blood clotting cause heart attacks? 3

Answer 10

• Coronary arteries carrying blood with oxygen to heart muscle is blocked
• Heart muscle not receiving any oxygen so cannot respire
• Causes damage and death to heart muscle cells

Question 11

What is a stroke?

Answer 11

Rapid loss of brain function due to disruption of blood supply to brain

Question 12

How does a blood clot cause a stroke?

Answer 12

• Blood clot blocks artery leading to brain

- Reduces amount of blood and therefore oxygen reaching brain for respiration

Question 13

What is deep vein thrombosis [DVT]?

Answer 13

Formation of a blood clot in a vein deep inside the body e.g leg vein

Question 14

What can DVT be caused by?

Answer 14

Prolonged inactivity e.g long flights

Question 15

What link is there between age and DVT?

Answer 15

Risk of DVT increases with age

Question 16

Define “atherosclerosis”

Answer 16

The hardening of arteries leading to heart disease and stroke

Question 17

Define “thrombosis”

Answer 17

Fatty deposits increase chance of blockage by a blood clot

Question 18

Describe the steps of atheroma formation 6

Answer 18

• Damage to the endothelium of arteries
• Causes an inflammatory response
• White blood cells migrate to the area
• WBCs and lipids from blood clump together to form fatty streaks
• Over time, more WBCs, lipids, fiborous tissue and calcium salts build up
• Harden to form a fibrous plaque - an atheroma

Question 19

What does an atheroma cause?

Answer 19

Blood pressure increase

Question 20

How does an atheroma lead to blood pressure increase?

Answer 20

• Artery becomes less elastic
• Lumen of artery narrows
• Restricts blood flow

Question 21

What is atherosclerosis an example of?

Answer 21

Positive feedback

Question 22

How is atherosclerosis an example of positive feedback?

Answer 22

• Atheromas forming makes further formation of atheromas more likely
• Atheromas make damage more likely
• As they rupture the wall of the endothelium