Cardiovascular Physiology Quiz

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Questions and Answers

What is the intrinsic rate of the SA node, the heart's pacemaker?

80 - 90 bpm

100 - 110 bpm (correct)

60 - 80 bpm

120 - 130 bpm

What role does the sympathetic nervous system play in heart rate regulation?

It increases heart rate. (correct)

It has no effect on heart rate.

It stabilizes heart rate.

It decreases heart rate.

What is the average resting heart rate for a healthy adult?

60 bpm

50 bpm

70 bpm (correct)

80 bpm

Which factor has the least influence on blood pressure regulation?

Ambient temperature Signup and view all the answers

Which of the following best describes diastole in the heart cycle?

Phase where the heart fills with blood. Signup and view all the answers

What is the formula for calculating Cardiac Output (CO)?

CO = HR x SV Signup and view all the answers

Which statement accurately describes preload?

Preload is the degree of myocardial stretching before contraction. Signup and view all the answers

How does afterload affect Stroke Volume (SV)?

Higher afterload leads to larger ESV, reducing SV. Signup and view all the answers

What does BP stand for in the equation BP = CO x PVR?

Blood Pressure Signup and view all the answers

Which factor does NOT directly influence Stroke Volume (SV)?

Heart Rate Signup and view all the answers

Which statement regarding Cardiac Output (CO) is correct?

CO can be decreased by lowering stroke volume. Signup and view all the answers

What role does the baroreflex play in regulating blood pressure?

It detects changes in blood pressure and adjusts cardiac output. Signup and view all the answers

What is a common misconception about the equation BP = CO x PVR?

BP is unaffected by changes in CO. Signup and view all the answers

What does diastole refer to in the cardiac cycle?

Filling of the ventricles with blood Signup and view all the answers

Which of the following accurately describes systolic pressure?

It is the pressure in the arteries during ventricular contraction. Signup and view all the answers

During which phase do the semilunar valves open?

During systole when ventricular pressure exceeds arterial pressure Signup and view all the answers

What happens to blood pressure during ventricular contraction?

Blood pressure increases due to pressure from contraction. Signup and view all the answers

How long does a complete cardiac cycle typically last at a heart rate of 72 bpm?

0.8 seconds Signup and view all the answers

What occurs during the isovolumetric contraction phase of the cardiac cycle?

All heart valves are closed and pressure is increasing. Signup and view all the answers

What primarily influences stroke volume?

End-diastolic volume and end-systolic volume Signup and view all the answers

During which part of the cardiac cycle do the atrioventricular (AV) valves open?

During diastole when ventricular pressure is lower than atrial pressure Signup and view all the answers

In the formula CO = HR x SV, what does 'SV' stand for?

Stroke Volume Signup and view all the answers

How does blood flow in the heart chambers?

From areas of higher to lower pressure Signup and view all the answers

At a resting heart rate of 72 bpm, how much blood is typically ejected with each heartbeat if the stroke volume is 70 ml?

4.0 litres Signup and view all the answers

Which valves prevent backflow of blood into the ventricles?

Semilunar valves Signup and view all the answers

What is the primary significance of measuring arterial blood pressure?

To evaluate how hard the heart works to pump blood Signup and view all the answers

Study Notes

Cardiovascular Physiology & Pharmacology (2)

Course title: Cardiovascular Physiology & Pharmacology (2)
Lecturer: Dr Stella Koutsikou
Module code: MSOP1003
Office location: Anson 307
Email address: [email protected]

Intrinsic Electrical Conduction System

Heart Rate (HR): Number of times the heart beats per minute (bpm)
HR is set by the sinoatrial (SA) node
HR is regulated by the autonomic nervous system
SA Node: Autorhythmic pacemaker of the heart
Intrinsic rate of the SA node: 100-110 bpm
Parasympathetic Nervous System: Control
Average resting HR: 70 bpm
Sympathetic Nervous System: Increases HR

Learning Objectives

Describe heart's mechanical events during systole and diastole
Understand cardiac output and factors affecting it
Align intrinsic excitability with myocardium contraction
Define blood pressure (BP) and factors affecting it
Understand normal control of BP
Pharmacology related to heart contractility and blood pressure control

The Cardiac Cycle

The orderly process of cardiac cell depolarization triggering atrial and ventricular contractions and relaxations
Diastole: Relaxation of cardiac muscle
Systole: Contraction of cardiac muscle
Depolarization of cardiac myocytes leads to contraction of cardiac muscle
The cardiac cycle repeats with every heartbeat

The Cardiac Cycle: Phases

The cardiac cycle is split into two major phases related to ventricular relaxation and contraction. Different points of the cycle are marked by the presence of various waves on the ECG.
Systole: Period of ventricular contraction and blood ejection (0.3 seconds)
Diastole: Ventricular relaxation and blood filling (0.5 seconds)
The typical heart rate = 72 bpm and the cycle takes ~0.8s

Blood Pressure

Blood flows from higher to lower pressure
Systole (contraction) increases pressure
Diastole (relaxation) reduces pressure
Valves open/close depending on pressure gradients
Semilunar valves open during systole when ventricular pressure higher than aortic pressure; AV values open during diastole
Measuring arterial blood pressure: pressure on artery walls in mmHg
Systolic pressure: Pressure when ventricles contract (higher number)
Diastolic pressure: Pressure when ventricles relax (lower number)

Mechanical Events During Cardiac Cycle

Detailed graphic representations showing atrial and ventricular pressure and volume changes over the cardiac cycle.
ECG (electrocardiogram) and phonocardiogram (sounds) activity aligned with pressure/volume changes.
Show different phases of the cycle: atrial depolarization and contraction, AV valve closure, isovolumetric contraction, ventricular ejection, etc.

Cardiac Output

CO = HR x SV
CO = Cardiac Output (liters/minute)
HR = Heart Rate (beats/minute)
SV = Stroke Volume (liters/heartbeat)

Factors Affecting HR, CO & BP

Vagus nerve (parasympathetic), Acetylcholine affects heart,innervates the atria, SA node and AV node.
Sympathetic nerves (sympathetic), Norepinephrine (NE), Beta-1 (β1) receptors, innervates atria, SA node and AV node.
Factors affecting SV: preload, afterload
Preload: degree of myocardium stretch before contraction determined by venous return (end diastolic volume).
Afterload: peripheral resistance contracting ventricular muscle needs to work against.
High preload = high SV ; High afterload = low SV

Beta Blockers

Beta blockers (e.g., Bisoprolol) reduce Ca2+ entering pacemaker cells during phase 4 and reduce conduction velocity, reducing HR and thus CO.

ANS Regulation of Heart Rate

Autonomic nervous system regulates CO and BP.
Baroreceptor reflex is essential for maintaining stable BP
BP=CO x PVR (Peripheral vascular resistance)

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Description

Test your knowledge on the intrinsic functions of the heart, including the SA node's rate and its regulation by the nervous system. This quiz also covers average resting heart rates and physiological terms like diastole. Perfect for students studying cardiovascular physiology or general biology.