Heart rate, Stroke volume, Cardiac output + Blood pressure

Question 1

What is heart rate?

Answer 1

The number of times your heart beats per minute.

Question 2

What is the heart controlled by?

Answer 2

• Neural factors.
• Hormonal factors.
• Intrinsic factors.

Question 3

What is the central command model of heart rate regulation?

Answer 3

• The central command model occurs during exercise + during the pre-exercise, anticipatory period.
• Impulses are sent from the cerebral cortex to working muscles and the cardiac centre of the medulla oblongata.
• This leads to an increase in heart rate and excitation to optimise tissue perfusion.

Question 4

What is stroke volume?

Answer 4

The amount of blood ejected by the left ventricle during systole.

Question 5

What does stroke volume regulate during rest and exercise?

Answer 5

• Rate of venous return.
• Arterial pressure.
• Ventricular contraction strength.
• Circulating hormones.

Question 6

What are the intrinsic determinants to regulate stroke volume?

Answer 6

• Frank Starling’s law.
• Laplace’s law.

Question 7

What is Frank Starlings law on stroke volume?

Answer 7

• An increase in venous return during exercise distends ventricles + stretches cardiac muscle.
• Therefore Increased stretch causes ventricular muscle fibres to contract more forcefully.

Question 8

What is LaPlace’s law on stroke volume?

Answer 8

• The heart muscle has a force-length relationship.
• It being overstretched causes the force of contraction to decrease.
• And so stroke volume decreases.

Question 9

Describe extrinsic regulation of stroke volume.

Answer 9

• An increase in sympathetic nerve activity + hormones released increases ventricular + atrial contractility.
• This enables a larger fraction of the cardiac cycle to be available.
• Ventricles relax quickly after contraction.
• So intraventricular pressure falls rapidly creating a pressure gradient for blood to into the ventricles.

Question 10

What is cardiac output?

Answer 10

The product of heart rate and stroke volume.

Question 11

What can cause an increase in cardiac output?

Answer 11

• Sympathetic nerves stimulating an increase in heart rate + contraction strength.
• Frank Starling’s law concerning stroke volume.
• End diastolic volume concerning stroke volume.

Question 12

What can cause a decrease in cardiac output?

Answer 12

• Parasympathetic nerves stimulate a decrease in heart rate.
• Arterial pressure concerning stroke volume.

Question 13

What is blood pressure?

Answer 13

The pressure of the circulating blood on the walls of the vessels.

Question 14

What is blood pressure determined by?

Answer 14

• Cardiac output.
• Vascular resistance.
• Blood volume.
• Blood viscosity.

Question 15

What can lead to an increase in blood pressure?

Answer 15

• Blood volume increases.
• Heart rate increases.
• Stroke volume increases.
• Blood viscosity increases.
• Peripheral resistance increases.