Answers to Study Guide Questions: Lecture 1-12 (2013)
Lecture 1: Electrical Conduction within the Heart
Which changes in ionic conductance (permeability) accompany the various phases of the pacemaker
1. 2. 4.
a) In zone 1, a decrease in K and an increase in PNa In zone 2, an increase in Ca
b) In zone 1, a decrease in K and an increase in PCa In zone 2, an increase in Na
c) In zone 3, a large increase inNa : In zone 4, an increase inKP and a decrease inCa
d) In zone 3, a large increase inCa: In zone 4, an increase in K and a decrease in PNa
e) A and D
The action potential that travels along the conduction pathway of the heart moves upward into the
ventricles (from the apex of the heart) via the ?
c) Purkinje Fibres
e) Bundle of His 2
Lecture 2: Cardiac Action Potential and the Electrocardiogram
Which changes in ionic conductance (permeability) DO NOT accompany the various phases of the
cardiac action potential?
a) In zone 0, an increase in PNa
b) In zone 1, a decrease in PNa a decrease in P Knd an increase in P Ca
c) In zone 2, a decrease in PNa and an increase in PCa
d) In zone 3, an increase in P and a decrease in P
e) C and D
The P and T waves of the ECG represent and , respectively.
a) Ventricular repolarisation and atrial depolarisation.
b) Atrial depolarisation and atrial repolarisation.
c) Ventricular depolarisation and atrial repolarisation.
d) Atrial depolarisation and ventricular repolarisation.
e) Atrial depolarisation and ventricular depolarisation.
The following ECG trace is representative of what cardiac disorder?
a) Atrial flutter.
b) Atrial fibrillation.
c) Ventricular fibrillation.
d) Wandering atrial pacemaker.
e) Second degree heart block. 3
Lecture 3: ECGs, Electrical Axis of the Heart and the Cardiac Cycle
In order for both of the semilunar valves to be open:
a) P (pulmonary artery) < P (right ventricle) and P (aorta) > P (left ventricle)
b) P (pulmonary artery) < P (right ventricle) and P (aorta) < P (left ventricle)
c) P (right ventricle) = P (aorta) and P (left ventricle) = P (pulmonary artery)
d) P (pulmonary artery) > P (right ventricle) and P (aorta) > P (left ventricle)
e) P (pulmonary artery) > P (right ventricle) and P (aorta) < P left ventricle
During Iso-volumetric contraction of the heart:
a) There is an increase in pressure without a change in volume.
b) The semilunar valves are closed.
c) The AV valves are closed
d) A and B
e) A, B and C 4
Use the following information and diagrams to calculate the mean electrical axis of the heart. Each
division on the leads equals 1.
Magnitude of the QRS complex in lead I = 2
Magnitude of the QRS complex in lead II = 5
Magnitude of the QRS complex in lead III = 3
a) Approximately 33°
b) Approximately 43°
c) Approximately 67°
d) Approximately 90°
e) Approximately 115°
Lecture 4: Cardiac Cycle Continued and Regulation of Cardiac Output
Cardiac output = ?
a) Blood pressure / Total peripheral resistance
b) Heart rate X stroke volume
c) Heart rate X EDV
d) Blood pressure X Total Peripheral Resistance
e) A and B
Use the following numbers to calculate stroke volume and pulse pressure.
Heart rate = 100 beats per minute
CO = 1 L/min
TPR = 0.1 mmHg min/ml
Diastolic pressure = 80 mmHg
a) SV = 10 ml; PP = 60 mmHg
b) SV = 10 ml/min; PP = 60 mmHg
c) SV = 100 ml: PP = 93 mmHg
d) SV = 80 ml; PP = 60 mmHg
e) SV = 10 ml; PP = 80 mmHg
An acetylcholinesterase inhibitor applied to the heart would the heart rate because it would
XXXXX the strength of signals. Note, within the synaptic cleft, acetylcholinesterase breaks
down acetylcholine into choline and acetyl-CoA
e) Increase…increase…sympathetic 6
Lecture 5: Regulation of Stroke Volume
How many of the following factors would lead to an increase in EDV?
a)1, b)2, c)3, d)4, e)5
Factor 1: An increase in heart rate.
Factor 2: Sinus tachycardia.
Factor 3: Increased pre-load.
Factor 4: Diaphragmatic contraction.
Factor 5: Decreased vagal tone to the heart.
Which of the following would not lead to an increase in stroke volume?
a) An increase in ventricular contractility.
b) Increased venous return.
c) An increase in aortic pressure.
e) Two of the above would not lead to an increase in stroke volume.
Sympathetic stimulation of the heart causes the Starling Curve to shift up due to a(n) increase
in ventricular contractility resulting from a(n) increase in calcium in cardiac myocytes.
a) Downwards; increase in ventricular contractility; increase in [Ca ]i in cardiac myocytes.
b) Upwards; decrease in ventricular contractility; increase in [Ca ]i in cardiac myocytes.
c) Upwards; increase in ventricular contractility; increase in [Ca ]i ++ cardiac myocytes.
d) Downwards; decrease in ventricular contractility; decrease in [Ca ]i i++cardiac myocytes.
e) Upwards; increase in ventricular contractility; increased rate of Ca sequestering in the
sarcoplasmic reticulum 7
Lecture 6: Regulation of Stroke Volume and Blood Flow
Cardiac output cannot increase indefinitely due to increases in HR because
SV decreases due to a decrease in filling time . This can be countered by sympathetic
a) Heart rate; stroke volume; ventricular contractility; sympathetic stimulation.
b) Heart rate; stroke volume; filling time; sympathetic stimulation.
c) Stroke volume; heart rate; filling time; parasympathetic stimulation.
d) Stroke volume; heart rate; ventricular contractility; sympathetic stimulation.
e) Heart rate; EDV; filling time; parasympathetic stimulation.
Veins have a large compliance and are often referred to as volume reservoirs. One of the important
functional consequences of this is:
a) During circulatory shock, blood is retained in the lower pressure venous reservoir therefore
preventing blood loss that would occur under high arterial pressure.
b) During exercise, ESV and cardiac output can be increased rapidly.
c) During exercise, cardiac output to the gut can be rapidly reduced.
d) During exercise, stroke volume and cardiac output can be increased rapidly.
e) During haemorrhage, EDV can be increased rapidly.
Note, the question above wasn’t covered in lecture this year.
Which of the following factors would be expected to have a greater influence on blood flow through
a vessel in a developing infant compared to an adult?
a) Haematocrit and foetal versus adult haemoglobin.
b) Blood vessel length.
c) The pressure gradient from the start of the vessel to the end of the vessel.
e) Plasma protein content. 8
Lecture 7: Blood Flow
Which of the following statements below identifies an advantage of a circulatory system that is
arranged in parallel?
a) Each organ receives incompletely oxygenated blood.
b) Blood flow can be regulated to individual organs.
c) The system becomes more compliant.
d) The system becomes more resistive.
e) Blood flow and blood oxygenation become uncoupled.
According to Poiseuille’s Law, which of the following factors would be expected to increase blood
flow through a vessel?
a) Increasing the radius of the vessel.
b) Increasing the blood vessel length.