Deep Vein Thrombosis

Question 1

what are the main groups of blood cells and their functions, and where are they produced

Answer 1

There are three groups of blood cells: erythrocytes (red cells), leukocytes (white cells), thrombocytes (platelets)

Red blood cells carry oxygen around the body, it does this when the O2 binds with a high affinity to
haemoglobin creating oxy-haemoglobin

White blood cells make up part of the immune system as their job is to defend the body against foreign
substances, these are also produced in the bone marrow

Platelets bind together and clot the blood (haemostasis) if there is a cut/graze on the skin surface, to stem the flow of blood.Thrombocytes do not have a nuclease and are made from fragments of cytoplasm. Thrombocytes are produced in the bone marrow by megakaryocytes

Question 2

Consider some of the main arteries and veins in the body, and revise the basic structure of vessel walls

Answer 2

Arteries are used to deliver oxygenated blood to the cells around the body. they are thin in diameter with thick walls to cope with the high pressure flow of the oxygenated blood
Veins are thicker in diameter but have thinner walls and valves to prevent backflowVeins are used to deliver deoxygenated blood to the heart from the cells/muscles in the body

The Aorta is known as the main artery and the Vena Cava is known as the main vein

Vessel walls have 3 layers:
• Tunica Interna: single layer of smooth squamous epithelium
• Tunica Media: smooth muscle layer (elastic fibers in in medium and larger arteries) – this is poorly developed in veins
• Tunica Extrena: outer connective tissue layer, thickest layer in veins

Question 3

Describe the formation of atherosclerosis and how this changes the vessel walls

Answer 3

Atherosclerosis is when deposits of material in artery walls forms plaque which narrows the lumen of the vessel walls restricting blood flow, this can cause a block
Plaque is formed by a build-up of cholesterol on the vessel walls which triggers an immune response
The immune response releases white blood cells to target the cholesterol
After the white blood cells attack the build-up they then die which is what causes a significant build-up
of plaque, restricting blood flow

Question 4

how can athereosclerosis lead to the formation of a blood thrombus

Answer 4

thrombus formation: endothelial cells become damaged from shear forces of high blood pressure, platelets adhere to occlude damage, aggregation of platelets leads to thrombus attached to vessel wall

Question 5

how does inactivity can contribute to thrombus formation

Answer 5

DVT’s usually occur in the calf veins, amongst the furthest from the heart and so blood is already moving at it’s slowest. Inactivity increases risk of thrombus formation as the skeletal muscles are not moving and so not performing their blood pumping function- this causes circulation to become sluggish, causing blood to pool and clots to form.

Obesity can add additional pressure to lower limbs and BVs, increasing poor circulation
Obesity increases the likelihood of higher cholesterol and restriction to blood vessels further increasing
the likelihood of DVT

Question 6

what are signs and symptoms of DVT

Answer 6

Sometimes DVT has no symptoms but you can get:
• Slow onset of unilateral leg pain
• Oedema
• Erythema and warmth
• Commonly in the calf
• In the thigh there is a greater risk of pulmonary embolism (signs of pulmonary embolism are hypoxia and breathlessness, chest pain and if severe, hypotension and tachycardia)

Question 7

what can be done for prevention of DVT

Answer 7

• Low cholesterol diet
• No smoking
• Moderate exercise
• Compression stockings post op
• Anti-coagulation injections

Question 8

describe embolus formation and risks it has

Answer 8

thrombus has broken free from vessel wall, carried in the circulation, can eventually obstruct another blood vessel and can cause pulmonary embolism, stroke, heart attack