L8-9: Heart as a pump, Excitable heart
79 Questions
2 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the cellular mechanism of cardiac contraction?

  • Ca2+ is released from the sarcoplasmic reticulum (SR)
  • ATP binds to myosin head and detaches head from actin
  • Ca2+ binds to actin and forms cross-bridges with myosin (correct)
  • Myosin pulls on actin to shorten the sarcomere and generate force

    • How does the force of cardiac contraction increase?

  • By decreasing the cytosolic Ca2+ concentration
  • By decreasing the number of cross-bridges formed
  • By increasing the cytosolic Ca2+ concentration (correct)
  • By increasing the pumping of Ca2+ into the sarcoplasmic reticulum (SR)

    • What is the purpose of the valves in the heart?

  • To generate force during contraction
  • To pump blood to the body
  • To regulate the flow of blood (correct)
  • To relax the cardiomyocytes

    • How does cardiac relaxation occur?

    <p>By actively pumping Ca2+ back into the sarcoplasmic reticulum (SR)</p> Signup and view all the answers

    What is the composition of the mammalian heart?

    <p>Two atria and two ventricles</p> Signup and view all the answers

    How do the pulmonary and systemic circuits work in the heart?

    <p>Simultaneously, one after the other in series</p> Signup and view all the answers

    What is the purpose of the two pumps in the heart?

    <p>To pump blood to the lungs and body</p> Signup and view all the answers

    How are cardiomyocytes activated during each heartbeat?

    <p>Every cardiomyocyte is activated during each heartbeat</p> Signup and view all the answers

    What happens when ATP binds to myosin head during cardiac relaxation?

    <p>The myosin head detaches from actin, breaking the cross-bridge</p> Signup and view all the answers

    Which phase of the cardiac cycle is characterized by the relaxation and falling pressure of the ventricular chambers?

    <p>Isovolumetric ventricular relaxation</p> Signup and view all the answers

    What is the main function of the overlapping diastole of the atria and ventricles during the cardiac cycle?

    <p>To maintain forward, unidirectional flow</p> Signup and view all the answers

    What is the difference between systole and diastole in terms of their durations?

    <p>Diastole is longer than systole</p> Signup and view all the answers

    What is the highest point on the blood pressure trace?

    <p>Systolic pressure</p> Signup and view all the answers

    What is the lowest point on the blood pressure trace?

    <p>Diastolic pressure</p> Signup and view all the answers

    What is the difference between systolic and diastolic pressure called?

    <p>Pulse pressure</p> Signup and view all the answers

    What is the average pressure across the full cardiac cycle called?

    <p>Mean pressure</p> Signup and view all the answers

    What is hypertension?

    <p>High blood pressure</p> Signup and view all the answers

    What is hypotension?

    <p>Low blood pressure</p> Signup and view all the answers

    During the cardiac cycle, the heart is in diastole for two-thirds of the time.

    <p>True</p> Signup and view all the answers

    The diastole of the atria and ventricles overlaps, which helps maintain forward, unidirectional flow.

    <p>True</p> Signup and view all the answers

    The blood pressure trace can be used to determine the systolic and diastolic pressure in arteries.

    <p>True</p> Signup and view all the answers

    Diastole is typically longer (60%) than systole (40%) in the cardiac cycle.

    <p>True</p> Signup and view all the answers

    The systemic arterial pressure is higher than the pulmonary arterial pressure.

    <p>True</p> Signup and view all the answers

    The highest point on the blood pressure trace is the systolic pressure.

    <p>True</p> Signup and view all the answers

    The lowest point on the blood pressure trace is the diastolic pressure.

    <p>True</p> Signup and view all the answers

    The pulse pressure is the difference between the systolic and diastolic pressure.

    <p>True</p> Signup and view all the answers

    The mean pressure is slightly shifted towards the diastolic pressure because more time is spent in diastole than systole.

    <p>True</p> Signup and view all the answers

    Hypertension refers to high blood pressure, while hypotension refers to low blood pressure.

    <p>True</p> Signup and view all the answers

    True or false: The mammalian cardiovascular system consists of a four-chambered heart with 2 atria and 2 ventricles.

    <p>True</p> Signup and view all the answers

    True or false: Arterial blood flows away from the heart.

    <p>True</p> Signup and view all the answers

    True or false: The pulmonary and systemic circuits in the heart work simultaneously, one after the other in series.

    <p>True</p> Signup and view all the answers

    True or false: Valves in the heart open and close to direct blood in a single direction, thus ensuring unidirectional flow

    <p>True</p> Signup and view all the answers

    True or false: Ca2+ is released from the sarcoplasmic reticulum (SR) and binds to actin to generate force during cardiac contraction.

    <p>True</p> Signup and view all the answers

    True or false: Every cardiomyocyte is activated during each heartbeat.

    <p>True</p> Signup and view all the answers

    True or false: Decreases in cytosolic Ca2+ concentration lead to cardiac relaxation.

    <p>True</p> Signup and view all the answers

    True or false: ATP binds to myosin head during cardiac relaxation to detach it from actin.

    <p>True</p> Signup and view all the answers

    True or false: The force of contraction can be altered by changing the Ca2+ released by the SR.

    <p>True</p> Signup and view all the answers

    True or false: The purpose of the valves in the heart is to ensure unidirectional flow of blood.

    <p>True</p> Signup and view all the answers

    During cardiac contraction, Ca2+ is released from the sarcoplasmic reticulum (SR) and binds to actin to form ______ with myosin.

    <p>cross-bridges</p> Signup and view all the answers

    Every ______ is activated during each heartbeat, unlike skeletal muscles which activate muscle fibers via recruitment.

    <p>cardiomyocyte</p> Signup and view all the answers

    The ______ cardiovascular system consists of a four-chambered heart with 2 atria and 2 ventricles.

    <p>mammalian</p> Signup and view all the answers

    Which node acts as the 'pacemaker' of the heart?

    <p>SA node</p> Signup and view all the answers

    What is the function of the AV node in the conduction pathway?

    <p>To create a pause between the conduction pathway</p> Signup and view all the answers

    Which structure distributes the contractile signal to the muscle cells of the left atrium?

    <p>Internodal bundle</p> Signup and view all the answers

    What is the function of the AV bundle and bundle branches in the conduction pathway?

    <p>To provide an electrical connection between the atria and ventricles</p> Signup and view all the answers

    Which cells rapidly propagate electrical conduction to the contractile cells of the ventricles?

    <p>Purkinje fibers</p> Signup and view all the answers

    What does an electrocardiogram (ECG) detect?

    <p>Difference or change in electrical activity of cardiac cells</p> Signup and view all the answers

    Which wave in an ECG represents atrial depolarization?

    <p>P wave</p> Signup and view all the answers

    During which phase of the cardiac cycle does ventricular depolarization occur?

    <p>QRS complex</p> Signup and view all the answers

    What happens during ventricular repolarization?

    <p>Ventricles begin to repolarize and relax</p> Signup and view all the answers

    When does ventricular repolarization complete?

    <p>After the T wave</p> Signup and view all the answers

    Which type of cells in the heart are responsible for triggering and spreading electrical impulses to all parts of the myocardium?

    <p>Conduction cells</p> Signup and view all the answers

    What is the main difference between electrical conduction cells and contractile cells in the heart?

    <p>Electrical conduction cells have a low actin and myosin content, while contractile cells have a high actin and myosin content</p> Signup and view all the answers

    What is the role of gap junctions in the intercalated disks of cardiac cells?

    <p>They facilitate electrochemical communication between cells</p> Signup and view all the answers

    What is NOT the composition of conduction cells in the heart?

    <p>Striated cardiac muscles with high actin and myosin content</p> Signup and view all the answers

    How do electrical impulses spread between electrical and contractile cells in the heart?

    <p>Through gap junctions</p> Signup and view all the answers

    What is the role of contractile cells in the heart?

    <p>To trigger and spread electrical impulses throughout the myocardium</p> Signup and view all the answers

    What is the main difference between electrical and contractile cells in terms of appearance?

    <p>Electrical cells have a pale striated appearance, while contractile cells have a striated appearance</p> Signup and view all the answers

    What is the function of conduction cells in the heart?

    <p>To trigger and spread electrical impulses throughout the myocardium</p> Signup and view all the answers

    Electrical conduction cells make up 1% of cardiac cells.

    <p>True</p> Signup and view all the answers

    Electrical conduction cells are modified cardiomyocytes.

    <p>True</p> Signup and view all the answers

    Electrical conduction cells have a high content of actin and myosin.

    <p>False</p> Signup and view all the answers

    Electrical conduction cells are involved in intercellular conduction within the heart.

    <p>True</p> Signup and view all the answers

    Electrical conduction cells have a pale striated appearance.

    <p>True</p> Signup and view all the answers

    Electrical conduction cells are mainly composed of nervous tissue.

    <p>False</p> Signup and view all the answers

    Contractile cells make up 99% of cardiac cells.

    <p>True</p> Signup and view all the answers

    Contractile cells have a high content of actin and myosin.

    <p>True</p> Signup and view all the answers

    Contractile cells are not involved in electrical conduction.

    <p>True</p> Signup and view all the answers

    Contractile cells are responsible for the contraction of the myocardium.

    <p>True</p> Signup and view all the answers

    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.

    <p>True</p> Signup and view all the answers

    True or false: The internodal bundle distributes the contractile signal to the right atrium muscle contractile cells.

    <p>True</p> Signup and view all the answers

    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.

    <p>True</p> Signup and view all the answers

    True or false: The AV bundle and bundle branches provide electrical connection between the atria and ventricles along the interventricular septum.

    <p>True</p> Signup and view all the answers

    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.

    <p>True</p> Signup and view all the answers

    True or false: Leads in an ECG detect the difference or change in electrical activity between two surface electrodes.

    <p>True</p> Signup and view all the answers

    True or false: Atrial depolarization is initiated by the AV node and causes the P wave in an ECG.

    <p>False</p> Signup and view all the answers

    True or false: Ventricular depolarization and atrial repolarization cause the QRS complex in an ECG.

    <p>True</p> Signup and view all the answers

    True or false: Ventricular repolarization starts from the base of the ventricles and causes the T wave in an ECG.

    <p>False</p> Signup and view all the answers

    True or false: Ventricular repolarization is complete when the ventricles are fully repolarized and relaxed.

    <p>True</p> Signup and view all the answers

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser