ECG Anatomy and Function Overview
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ECG Anatomy and Function Overview

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Questions and Answers

What does the P-wave in an ECG represent?

  • Atrial contraction
  • Ventricular repolarisation
  • Atrial depolarisation (correct)
  • Ventricular depolarisation
  • The T-wave indicates the depolarisation of the ventricles.

    False

    What does the QRS complex signify in a standard ECG?

    Ventricular depolarisation

    The _____ carries deoxygenated blood from the right ventricle to the lungs.

    <p>pulmonary artery</p> Signup and view all the answers

    Which layer is comparatively thinner in veins compared to arteries?

    <p>Tunica media</p> Signup and view all the answers

    Match the parts of the heart's electrical activity with their corresponding features:

    <p>P-wave = Atrial depolarisation QRS complex = Ventricular depolarisation T-wave = Ventricular repolarisation Systole = Ventricular contraction</p> Signup and view all the answers

    What determines the heart rate of an individual using an ECG?

    <p>Count the number of QRS complexes in a given time period.</p> Signup and view all the answers

    Differences in the shape of ECGs among individuals indicate normal function.

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

    What is the primary function of the sino-atrial node (SAN)?

    <p>To act as a pacemaker for the heart</p> Signup and view all the answers

    What percentage does the flow of blood into the ventricles increase by?

    <p>30 percent</p> Signup and view all the answers

    The walls of the ventricles are thinner than those of the atria.

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

    How many beats per minute does a normal human heart beat on average?

    <p>72</p> Signup and view all the answers

    The ventricles contract during diastole.

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

    The _______ fibres are responsible for conducting the action potential throughout the ventricular musculature.

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

    What prevents the backflow of blood into the ventricles during ventricular relaxation?

    <p>Semilunar valves</p> Signup and view all the answers

    The phase when the atria relax and the ventricles contract is called __________.

    <p>ventricular systole</p> Signup and view all the answers

    Which valve prevents the backward flow of blood from the ventricles to the atria?

    <p>Atrioventricular valve</p> Signup and view all the answers

    Match the following heart chambers with their functions:

    <p>Atria = Receive blood from veins Ventricles = Pump blood to arteries Tricuspid valve = Prevent backflow from right ventricle Bicuspid valve = Prevent backflow from left ventricle</p> Signup and view all the answers

    The atrial systole occurs when the SAN generates an action potential.

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

    What is the role of the atrio-ventricular node (AVN) in the heart?

    <p>It relays the action potential from the atria to the ventricles.</p> Signup and view all the answers

    What initiates the action potential that starts the cardiac cycle?

    <p>Sinoatrial node (SAN)</p> Signup and view all the answers

    Match the following components of the heart with their functions:

    <p>Sino-atrial node (SAN) = Pacemaker of the heart Atrioventricular node (AVN) = Relays electrical signals Purkinje fibres = Conducts signals to ventricles Semilunar valves = Prevents backflow to the heart</p> Signup and view all the answers

    The heart beats approximately 72 times every hour.

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

    What is the term for the cyclic sequence of events during a heartbeat?

    <p>Cardiac cycle</p> Signup and view all the answers

    What type of blood can be donated to persons with any other blood group?

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

    Individuals with AB blood group can accept blood only from AB donors.

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

    What are the two surface antigens that determine the ABO blood group?

    <p>A and B</p> Signup and view all the answers

    Group 'AB' blood contains ___ antibodies in its plasma.

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

    Which blood group has anti-A and anti-B antibodies in plasma?

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

    A person with blood type O can receive blood from group A.

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

    What is the term for the destruction of RBC caused by incompatible blood transfusion?

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

    Match the blood groups with their corresponding characteristics:

    <p>A = Anti-B antibodies, can donate to A and AB B = Anti-A antibodies, can donate to B and AB AB = No antibodies, universal recipient O = Anti-A and anti-B antibodies, universal donor</p> Signup and view all the answers

    What is the primary role of fibrins in blood coagulation?

    <p>To form a network that traps blood components</p> Signup and view all the answers

    Prothrombin is the active form that converts fibrinogen into fibrins.

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

    What fluid is collected by the lymphatic system from the spaces between tissue cells?

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

    Calcium ions play a very important role in _____ process.

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

    Which enzyme is essential for the conversion of prothrombin to thrombin?

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

    The interstitial fluid is composed mainly of large proteins and formed elements of blood.

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

    What type of mechanism prevents excessive blood loss from the body?

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

    Match the following components with their roles in the coagulation process:

    <p>Thrombin = Converts fibrinogen to fibrin Fibrin = Forms clots Prothrombin = Inactive precursor of thrombin Thrombokinase = Catalyzes the conversion of prothrombin</p> Signup and view all the answers

    Study Notes

    ECG and Cardiac Function

    • ECG measures the heart's electrical activity through multiple chest leads.
    • P-wave signifies atrial depolarization, leading to atrial contraction.
    • QRS complex indicates ventricular depolarization, initiating ventricular contraction and marked by the start of systole.
    • T-wave reflects ventricular repolarization, concluding systole.
    • Counting QRS complexes aids in determining heart rate.
    • Variations in ECG shape suggest possible heart abnormalities, making ECG clinically significant.

    Double Circulation and Blood Vessels

    • Blood circulates via arteries and veins, each comprising three layers: tunica intima (endothelium), tunica media (smooth muscle and elastic fibers), and tunica externa (fibrous connective tissue).
    • Right ventricle pumps deoxygenated blood into the pulmonary artery; the left ventricle pumps oxygenated blood into the aorta.
    • Blood returns oxygenated from the lungs via pulmonary veins to the left atrium, forming pulmonary circulation.
    • Valves prevent backflow, ensuring unidirectional blood flow.

    Cardiac Muscle Structure

    • The heart is composed entirely of cardiac muscles, with thicker ventricular walls than atrial walls.
    • Nodal tissue regulates heart muscle contractions, including the sino-atrial node (SAN) as the primary pacemaker, generating 70-75 action potentials per minute.
    • The atrio-ventricular node (AVN) and AV bundle distribute action potentials throughout the ventricles via Purkinje fibers.

    Cardiac Cycle

    • The cardiac cycle begins with all chambers relaxed (joint diastole).
    • Blood flows from atria to ventricles as tricuspid and bicuspid valves open.
    • SAN action potential triggers atrial contraction (atrial systole), increasing ventricular blood volume.
    • Action potential travels through the AVN and AV bundle, causing ventricular contraction (ventricular systole) after which both the atria and ventricles relax.
    • Cardiac cycles occur approximately 72 times per minute.

    Blood Groups and Transfusions

    • Blood types are classified primarily into ABO and Rh systems based on surface antigens A and B and corresponding antibodies in plasma.
    • Group A: A antigens, anti-B antibodies; compatible with A and O.
    • Group B: B antigens, anti-A antibodies; compatible with B and O.
    • Group AB: A and B antigens, no antibodies; universal recipient.
    • Group O: No antigens, anti-A and anti-B antibodies; universal donor.

    Blood Clotting Mechanism

    • Blood clotting, or coagulation, forms a scab and involves fibrin threads trapping dead cells.
    • Fibrinogen converts to fibrin through thrombin action, triggered by prothrombin in a cascade involving various plasma factors.
    • Platelet release during injury activates coagulation; tissue factors can also initiate the process.
    • Calcium ions are crucial for the clotting mechanism.

    Lymphatic System

    • Interstitial fluid, a result of blood capillary exchange, contains minerals similar to plasma.
    • The lymphatic system collects interstitial fluid (lymph), returning it to major veins, aiding in nutrient and gas exchange between blood and cells.

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    Description

    This quiz focuses on the standard ECG and its components, including the significance of the P-wave and QRS complex in heart function. Understanding these aspects is crucial for evaluating cardiac electrical activity. Test your knowledge on the different aspects of ECG readings and their interpretations.

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