Cardiovascular Physiology

What are the main roles of the cardiovascular system?

Transport of nutrients, metabolic products, hormones; regulation of pH, osmolality; defense; heat distribution.

How many circulations are arranged in series in the cardiovascular system?

Two: systemic and pulmonary.

What defines diastole?

Ventricular filling (relaxation).

What defines systole?

Ejection of blood into arteries (contraction).

What determines blood flow through a circulation?

Pressure gradient (ΔP) and resistance (R).

How is Cardiac Output (CO) calculated?

CO = Heart Rate (HR) × Stroke Volume (SV).

What is typical resting CO?

~5L/min.

What is the Ca2+ sensor in cardiac muscle?

Troponin (not calmodulin like in smooth muscle).

Where does electrical activity in the heart originate?

Sinoatrial (SA) node.

What is the role of the annulus fibrosis?

Electrically insulates atria from ventricles.

What event does the P wave represent?

Atrial depolarization.

What event does the QRS complex represent?

Ventricular depolarization.

What event does the T wave represent?

Ventricular repolarization.

What neurotransmitter is released by sympathetic nerves?

Noradrenaline (adrenaline).

What neurotransmitter is released by parasympathetic nerves?

Acetylcholine.

What is the intrinsic rate of firing of SAN cells?

~100-110 action potentials per minute.

What is the cardiac cycle sequence?

Ventricular filling → Atrial contraction → Isovolumetric contraction → Ventricular ejection → Isovolumetric relaxation.

What is preload?

Degree of stretch of the ventricles due to end diastolic pressure (EDV).

What is Starling's Law of the heart?

Force of contraction is proportional to initial fiber length during diastole.

What mainly controls Mean Arterial Pressure (MAP)?

Cardiac Output (CO) × Total Peripheral Resistance (TPR).

How does sympathetic stimulation affect heart rate?

Increases heart rate and contractility.

How does parasympathetic stimulation affect heart rate?

Decreases heart rate.

What happens to BP as blood moves through the vascular system?

Pressure decreases due to energy loss to vessel walls.

Where does most blood pressure drop occur?

Across the arterioles (major resistance vessels).