Haemodynamics: Pulse Pressure, Mean Blood Pressure, and Arterial Compliance

Vasoconstriction or vasodilation: Doubling the radius in a rigid tube increases flow 24 times, governed by Poiseuille's law in compliant tubes where small changes in radius significantly impact flow due to the radius to the power of 4.

Atheroma: A fatty deposit on artery walls that decreases blood flow due to Poiseuille's Law, which can lead to tissue hypoxia with advanced atheromas reducing blood flow to around 5% of normal.

Cardiac Output: The total blood flow out of the heart is the cardiac output, a key parameter in heart function, essential for diagnosing heart problems. Cardiac output is the product of heart rate and stroke volume.

Measuring cardiac output: Fluid flow through a pipe equals pressure divided by resistance, making the heart's output equal to blood pressure divided by total peripheral resistance. Cardiac output can be measured using non-invasive methods like Doppler ultrasound.

Factors affecting cardiac output: Oxygen requirements of vital organs, digestive state, temperature, and exercise.

Cardiovascular changes during exercise: Increased heart rate, increased stroke volume, and increased oxygen uptake.

Stroke volume during exercise: Stroke volume reaches a plateau during moderate work and remains unchanged at high intensity, maintained due to atrial contraction and increased ventricular contractility.

Oxygen uptake during exercise: Increases tenfold, more than cardiac output, due to increased respiration rate, depth, and pulmonary arteriolar relaxation.

Capillary structure and blood flow: Capillaries have a small diameter, no smooth muscle, allowing fluid pressures of over 20 mm Hg, and blood flow is affected as red blood cells deform to move through capillaries smaller than their diameter.

Arterial compliance and Poiseuille's law: Arterial compliance is crucial as small changes in radius significantly impact flow due to the radius to the power of 4, as explained by Poiseuille's Law, which also relates to changes in pressure in the circulation.

Cardiac output, peripheral resistance, and blood pressure: Cardiac output is the product of heart rate and stroke volume, while blood pressure is the pressure required to move fluid against resistance. Peripheral resistance can be affected by vasoconstriction or vasodilation.

Laplace's Law: Relates vessel radius to pressure and is important for understanding aneurysm formation, as an increase in vessel radius leads to a decrease in wall tension, making the vessel more susceptible to rupture.

Vasoconstriction or vasodilation: Doubling the radius in a rigid tube increases flow 24 times, governed by Poiseuille's law in compliant tubes where small changes in radius significantly impact flow due to the radius to the power of 4.

Atheroma: A fatty deposit on artery walls that decreases blood flow due to Poiseuille's Law, which can lead to tissue hypoxia with advanced atheromas reducing blood flow to around 5% of normal.

Cardiac Output: The total blood flow out of the heart is the cardiac output, a key parameter in heart function, essential for diagnosing heart problems. Cardiac output is the product of heart rate and stroke volume.

Measuring cardiac output: Fluid flow through a pipe equals pressure divided by resistance, making the heart's output equal to blood pressure divided by total peripheral resistance. Cardiac output can be measured using non-invasive methods like Doppler ultrasound.

Factors affecting cardiac output: Oxygen requirements of vital organs, digestive state, temperature, and exercise.

Cardiovascular changes during exercise: Increased heart rate, increased stroke volume, and increased oxygen uptake.

Stroke volume during exercise: Stroke volume reaches a plateau during moderate work and remains unchanged at high intensity, maintained due to atrial contraction and increased ventricular contractility.

Oxygen uptake during exercise: Increases tenfold, more than cardiac output, due to increased respiration rate, depth, and pulmonary arteriolar relaxation.

Capillary structure and blood flow: Capillaries have a small diameter, no smooth muscle, allowing fluid pressures of over 20 mm Hg, and blood flow is affected as red blood cells deform to move through capillaries smaller than their diameter.

Arterial compliance and Poiseuille's law: Arterial compliance is crucial as small changes in radius significantly impact flow due to the radius to the power of 4, as explained by Poiseuille's Law, which also relates to changes in pressure in the circulation.

Cardiac output, peripheral resistance, and blood pressure: Cardiac output is the product of heart rate and stroke volume, while blood pressure is the pressure required to move fluid against resistance. Peripheral resistance can be affected by vasoconstriction or vasodilation.

Laplace's Law: Relates vessel radius to pressure and is important for understanding aneurysm formation, as an increase in vessel radius leads to a decrease in wall tension, making the vessel more susceptible to rupture.