Problems with vascular flow

In most straight blood vessels, flow is:

• Turbulent

• Laminar

• the volume of fluid passing a given point per unit of time (e.g. cm3/s)

• Consistent at any two points of the cardiovascular system

Answer explanation

Laminar = a constant stream

When does blood flow become turbulent?

• Under conditions of high flow

• Under conditions of low flow

• When the Reynolds number is surpassed

• Vasodilation

Answer explanation

Reynolds number is a way to predict under ideal conditions when turbulence will occur. The equation for Reynolds number is:

 

 

Where V = mean velocity, D = vessel diameter, ρ = blood density, and η = blood viscosity

What are the characteristics of the haemorrhage: Petechiae

• Minute haemorrhage, 1-2mm diameter

• Subcutaneous haematoma 1-2mm diameter

• Large haemorrhage 3-10mm diameter

• Subcutaneous Haematoma 3-10mm diameter

Answer explanation

Minute haemorrhage of skin and mucosa 

1-2mm

Due to thrombocytopenia, clotting factor deficiency, increased capillary pressure

What are the 3 factors that cause pathological thrombosis?

What are Mural thrombi?

• An arterial thrombi that partially occludes the vessel = minor adverse events

• A venous thrombi that partially occludes the vessel = minor adverse events

• An arterial thrombi that completely occludes vessel = major adverse events

• A venous thrombi that completely occludes vessel = major adverse events

Characteristics of venous thrombosis

• Formed under low shear flow

  &

  Fibrin and erythrocyte rich 

• Formed under high shear flow

  &

  Fibrin and erythrocyte rich 

• Formed under high shear flow

  &

  Platelet rich 

• Formed under low shear flow

  &

  Platelet rich 

What is reactive hyperaemia?

• Local vasodilation in response to oxygen debt or accumulation of metabolic waste

• Increased vasodilation in response to period of activation (e.g. exercise)

• Local increase in the volume of blood in tissues in response to change in environment – adaptive change

What are the three main associations of shock?

• Hypotension

• Hypoperfusion

• Cellular Hypoxia

• Hyperperfusion

• Vasodilation

What constitutes hypovalemic shock?

• 20% blood loss

• 30% blood loss

• 25% blood loss

• 15% blood loss

What is an aneurism