The microgravity environment causes significant changes to cardiovascular and cerebrovascular haemodynamics. Due to the absence of gravity, a redistribution of body fluids occurs and can result in significant disease including intracranial hypertension and jugular venous thrombosis. In this project, a lumped parameter computer model of the cardiovascular system will be used to explore the effect of microgravity on the cerebrovascular haemodynamics. Specifically, an established model of the cardiovascular system in microgravity will be extended to include the blood flow to the brain. Using the updated model, the effects of increasing the resistance to venous drainage will be used to simulate the effects of jugular venous thrombosis.