79 Questions
What is the cellular mechanism of cardiac contraction?
Ca2+ binds to actin and forms cross-bridges with myosin
How does the force of cardiac contraction increase?
By increasing the cytosolic Ca2+ concentration
What is the purpose of the valves in the heart?
To regulate the flow of blood
How does cardiac relaxation occur?
By actively pumping Ca2+ back into the sarcoplasmic reticulum (SR)
What is the composition of the mammalian heart?
Two atria and two ventricles
How do the pulmonary and systemic circuits work in the heart?
Simultaneously, one after the other in series
What is the purpose of the two pumps in the heart?
To pump blood to the lungs and body
How are cardiomyocytes activated during each heartbeat?
Every cardiomyocyte is activated during each heartbeat
What happens when ATP binds to myosin head during cardiac relaxation?
The myosin head detaches from actin, breaking the cross-bridge
Which phase of the cardiac cycle is characterized by the relaxation and falling pressure of the ventricular chambers?
Isovolumetric ventricular relaxation
What is the main function of the overlapping diastole of the atria and ventricles during the cardiac cycle?
To maintain forward, unidirectional flow
What is the difference between systole and diastole in terms of their durations?
Diastole is longer than systole
What is the highest point on the blood pressure trace?
Systolic pressure
What is the lowest point on the blood pressure trace?
Diastolic pressure
What is the difference between systolic and diastolic pressure called?
Pulse pressure
What is the average pressure across the full cardiac cycle called?
Mean pressure
What is hypertension?
High blood pressure
What is hypotension?
Low blood pressure
During the cardiac cycle, the heart is in diastole for two-thirds of the time.
True
The diastole of the atria and ventricles overlaps, which helps maintain forward, unidirectional flow.
True
The blood pressure trace can be used to determine the systolic and diastolic pressure in arteries.
True
Diastole is typically longer (60%) than systole (40%) in the cardiac cycle.
True
The systemic arterial pressure is higher than the pulmonary arterial pressure.
True
The highest point on the blood pressure trace is the systolic pressure.
True
The lowest point on the blood pressure trace is the diastolic pressure.
True
The pulse pressure is the difference between the systolic and diastolic pressure.
True
The mean pressure is slightly shifted towards the diastolic pressure because more time is spent in diastole than systole.
True
Hypertension refers to high blood pressure, while hypotension refers to low blood pressure.
True
True or false: The mammalian cardiovascular system consists of a four-chambered heart with 2 atria and 2 ventricles.
True
True or false: Arterial blood flows away from the heart.
True
True or false: The pulmonary and systemic circuits in the heart work simultaneously, one after the other in series.
True
True or false: Valves in the heart open and close to direct blood in a single direction, thus ensuring unidirectional flow
True
True or false: Ca2+ is released from the sarcoplasmic reticulum (SR) and binds to actin to generate force during cardiac contraction.
True
True or false: Every cardiomyocyte is activated during each heartbeat.
True
True or false: Decreases in cytosolic Ca2+ concentration lead to cardiac relaxation.
True
True or false: ATP binds to myosin head during cardiac relaxation to detach it from actin.
True
True or false: The force of contraction can be altered by changing the Ca2+ released by the SR.
True
True or false: The purpose of the valves in the heart is to ensure unidirectional flow of blood.
True
During cardiac contraction, Ca2+ is released from the sarcoplasmic reticulum (SR) and binds to actin to form ______ with myosin.
cross-bridges
Every ______ is activated during each heartbeat, unlike skeletal muscles which activate muscle fibers via recruitment.
cardiomyocyte
The ______ cardiovascular system consists of a four-chambered heart with 2 atria and 2 ventricles.
mammalian
Which node acts as the 'pacemaker' of the heart?
SA node
What is the function of the AV node in the conduction pathway?
To create a pause between the conduction pathway
Which structure distributes the contractile signal to the muscle cells of the left atrium?
Internodal bundle
What is the function of the AV bundle and bundle branches in the conduction pathway?
To provide an electrical connection between the atria and ventricles
Which cells rapidly propagate electrical conduction to the contractile cells of the ventricles?
Purkinje fibers
What does an electrocardiogram (ECG) detect?
Difference or change in electrical activity of cardiac cells
Which wave in an ECG represents atrial depolarization?
P wave
During which phase of the cardiac cycle does ventricular depolarization occur?
QRS complex
What happens during ventricular repolarization?
Ventricles begin to repolarize and relax
When does ventricular repolarization complete?
After the T wave
Which type of cells in the heart are responsible for triggering and spreading electrical impulses to all parts of the myocardium?
Conduction cells
What is the main difference between electrical conduction cells and contractile cells in the heart?
Electrical conduction cells have a low actin and myosin content, while contractile cells have a high actin and myosin content
What is the role of gap junctions in the intercalated disks of cardiac cells?
They facilitate electrochemical communication between cells
What is NOT the composition of conduction cells in the heart?
Striated cardiac muscles with high actin and myosin content
How do electrical impulses spread between electrical and contractile cells in the heart?
Through gap junctions
What is the role of contractile cells in the heart?
To trigger and spread electrical impulses throughout the myocardium
What is the main difference between electrical and contractile cells in terms of appearance?
Electrical cells have a pale striated appearance, while contractile cells have a striated appearance
What is the function of conduction cells in the heart?
To trigger and spread electrical impulses throughout the myocardium
Electrical conduction cells make up 1% of cardiac cells.
True
Electrical conduction cells are modified cardiomyocytes.
True
Electrical conduction cells have a high content of actin and myosin.
False
Electrical conduction cells are involved in intercellular conduction within the heart.
True
Electrical conduction cells have a pale striated appearance.
True
Electrical conduction cells are mainly composed of nervous tissue.
False
Contractile cells make up 99% of cardiac cells.
True
Contractile cells have a high content of actin and myosin.
True
Contractile cells are not involved in electrical conduction.
True
Contractile cells are responsible for the contraction of the myocardium.
True
True or false: The SA node is responsible for initiating electrical depolarization in the right atrium and spreading it to the left atrium and AV node.
True
True or false: The internodal bundle distributes the contractile signal to the right atrium muscle contractile cells.
True
True or false: The AV node is a relatively slow conductor and creates a pause in the conduction pathway to allow for the completion of atrial systole and ventricular depolarisation preparation.
True
True or false: The AV bundle and bundle branches provide electrical connection between the atria and ventricles along the interventricular septum.
True
True or false: The Purkinje fibers rapidly propagate electrical conduction to the contractile cells of the ventricles, causing a ventricular contraction from the apex upwards and outwards.
True
True or false: Leads in an ECG detect the difference or change in electrical activity between two surface electrodes.
True
True or false: Atrial depolarization is initiated by the AV node and causes the P wave in an ECG.
False
True or false: Ventricular depolarization and atrial repolarization cause the QRS complex in an ECG.
True
True or false: Ventricular repolarization starts from the base of the ventricles and causes the T wave in an ECG.
False
True or false: Ventricular repolarization is complete when the ventricles are fully repolarized and relaxed.
True
Test your knowledge of the basic design and functions of the mammalian cardiovascular system with this quiz. Explore topics such as the four chambered heart, unidirectional flow, arterial and venous blood circulation, and the pulmonary and systemic circuits. Challenge yourself with questions on the structure and function of the heart and how blood flows through the cardiovascular system.
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