Cardiovascular 1 and 2

How is Heart Rate Variability (HRV) determined?

By measuring the time intervals between each R wave on an electrocardiogram.

What are the main factors that influence Mean Arterial Pressure (MAP)?

• Cardiac output: The total volume of blood pumped by the heart each minute.

• Stroke volume: The amount of blood ejected with each heartbeat.

• Baroreceptors: Sensors that help regulate blood pressure.

What are the three primary regulators of stroke volume?

1. Preload

2. Afterload: An increased afterload decreases stroke volume.

3. Contractility: The strength of ventricular contractions.

What is afterload?

The resistance the left ventricle (LV) must overcome to eject blood into the aorta. A higher resistance in the aorta leads to increased afterload, which limits stroke volume.

What occurs during systole?

The phase of the cardiac cycle where the heart muscles contract, pumping blood from the heart chambers into the arteries.

What is diastole?

The phase of the cardiac cycle where the heart muscle relaxes, allowing the atria and ventricles to fill with blood. This occurs after systole and is vital for ensuring sufficient blood volume in the heart before the next contraction.

What does a drop in hematocrit mean?

A drop in hematocrit indicates a reduced proportion of red blood cells in blood, which can signal anemia or fluid overload.

MAP

What is cardiovascular drift?

A gradual increase in heart rate during prolonged exercise at a constant intensity, accompanied by a decrease in stroke volume.

What is the Fick equation?

A mathematical formula used to calculate cardiac output based on oxygen consumption and the difference in oxygen content in arterial and venous blood.

a-VO2 Difference

The difference in oxygen content between arterial and venous blood, indicating how much oxygen is used by tissues.

If someone is NOT fit:

• There will be more O2 on the venous side

If some IS fit:

• There will be more O2 on the arteriole side

What is endothelium mediated vasodilation?

The process by which the endothelium (inner lining of blood vessels) releases substances that cause relaxation of the vascular smooth muscle, leading to dilation of the blood vessels and increased blood flow.

• Nitric Oxide