Heart Anatomy and Function Quiz
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Questions and Answers

What is the role of the semilunar (SL) valves in the heart?

  • They close during ventricular systole.
  • They allow blood to flow into the ventricles.
  • They open when pressure in the ventricle is higher than in the aorta. (correct)
  • They prevent backflow into the atria.

    • Isovolumetric contraction occurs when there is a change in volume in the heart.

    False

    What type of muscle contractions do myocardial cells undergo?

    Involuntary contractions

    The thick filaments in myocardial cells are primarily composed of __________.

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

    Match the following heart valve actions with their corresponding states:

    <p>SL valves open = Higher pressure in the ventricle than in aorta AV valves close = Higher pressure in the ventricle during systole AV valves open = Passive filling of the ventricle SL valves close = Pressure in the ventricle drops below aorta</p> Signup and view all the answers

    What is the primary function of systemic circulation?

    <p>To transport blood from the heart to the body and back</p> Signup and view all the answers

    Myocardial infarction refers to reduced blood flow to the heart muscle.

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

    What supplies the heart muscle with blood?

    <p>Coronary circulation</p> Signup and view all the answers

    The heart weighs approximately ______ grams.

    <p>250-300</p> Signup and view all the answers

    Match the type of circulation with its description:

    <p>Pulmonary circulation = Blood travels from the heart to the lungs and back Systemic circulation = Blood travels from the heart to the body and back Coronary circulation = Supplies the heart muscle with blood Venous drainage = Collects waste from cardiac muscle</p> Signup and view all the answers

    Which heart valve prevents backflow from the left ventricle to the left atrium?

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

    What is the main purpose of the heart valves?

    <p>To allow blood flow between heart chambers and arteries</p> Signup and view all the answers

    The first heart sound (S1) is caused by the closure of the semilunar valves.

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

    What condition is characterized by the inflammation of the myocardium?

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

    The space between the inner and outer pericardial membranes is filled with __________.

    <p>pericardial fluid</p> Signup and view all the answers

    Match the following conditions with their descriptions:

    <p>Stenosis = Narrowing of heart valves, restricting blood flow Pericarditis = Inflammation of the pericardium Endocarditis = Inflammation of the endocardium Myocarditis = Inflammation of the myocardium</p> Signup and view all the answers

    Which heart sound is associated with the closure of semilunar valves?

    <p>S2</p> Signup and view all the answers

    What is the primary layer of the heart wall that consists of specialized cardiac muscle?

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

    Heart murmurs are always a sign of a serious heart condition.

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

    What is the primary function of the specialized cardiac muscle conducting cells?

    <p>Set the rhythm of the heart</p> Signup and view all the answers

    Nerve impulses and hormones are responsible for establishing the fundamental rhythm of the heart.

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

    What does the QRS complex represent in an ECG?

    <p>Ventricular depolarization</p> Signup and view all the answers

    During ventricular systole, the pressure inside the ventricle is higher than in the ______.

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

    Match the following ECG components with their associated activity:

    <p>P wave = Atrial depolarization QRS complex = Ventricular depolarization T wave = Ventricular repolarization</p> Signup and view all the answers

    What percentage of ventricular filling occurs during passive ventricular filling?

    <p>70%</p> Signup and view all the answers

    The pressure in the aortic trunk is lower than that in the left ventricle during heart contraction.

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

    What happens to the pressure in the ventricle as it relaxes?

    <p>The pressure drops.</p> Signup and view all the answers

    The heart has intrinsic rhythmical electrical activity leading to continuous ______.

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

    Which element modifies the timing and strength of each heart beat?

    <p>Both B and C</p> Signup and view all the answers

    Study Notes

    Cardiovascular System 1

    • Lecture aims: blood flow and circulation, heart structure, heart function

    Blood Flow and Circulation

    • Systemic and pulmonary circulation
    • Blood flow through the heart
    • Coronary circulation

    Circulation

    • Pulmonary circulation: blood travels from the heart to the lungs and back to the heart
    • Systemic circulation: blood travels from the heart to the body and back to the heart

    Blood flow through the heart

    • Path of blood through the heart, including pulmonary capillaries of the right lung, right atrium, right ventricle, pulmonary capillaries of the left lung, left atrium, left ventricle, and capillaries of the trunk and lower limbs
    • Key structures: pulmonary capillaries, right atrium, right ventricle, pulmonary capillaries of left lung, left atrium, left ventricle
    • Movement of blood through the heart is related to the opening and closing of valves

    Coronary Circulation

    • Supplies heart muscle with blood
    • High demand for oxygen and nutrients
    • Diffusion through tissues is insufficient
    • Vessels run in sulci (grooves) on the heart surface

    Coronary Circulation: The Arteries

    • Branches off aorta above aortic semilunar valve (at aortic sinuses)
    • High pressure
    • Elastic

    Coronary Circulation: The Veins

    • Run alongside arteries
    • Collect waste from cardiac muscle
    • Venous drainage mainly via coronary sinus (posterior), emptying into right atrium

    Coronary Circulation: If It Goes Wrong

    • Myocardial ischemia: reduced blood flow to myocardium
    • Angina pectoris: associated pain
    • Myocardial infarction (MI): complete obstruction of blood flow to part of myocardium

    The Heart (Structure)

    • Heart valves and sounds
    • Heart tissue

    The Heart: Overview

    • Pump of the cardiovascular system
    • Weighs approximately 250-300g
    • Pumps 30 times its own weight (5L) per minute
    • Muscular organ that never rests
    • Contracts approximately 3 billion times during an average human lifetime

    Thickness of Cardiac Walls

    • Blood pressure (BP) in aorta is 120mmHg
    • BP in pulmonary trunk is 30mmHg
    • Why the difference?

    Heart Valves

    • Valves open to allow blood flow from atria into ventricles (atrioventricular valves: bicuspid (mitral) and tricuspid); and from ventricles into corresponding arteries (semilunar valves)
    • Stenosis: narrowing of heart valves, restricting blood flow

    Heart Sounds

    • Sounds of heartbeat due to turbulence in blood flow and valve closure
    • 1st heart sound (lubb) - S1 (closure of AV valves)
    • 2nd heart sound (dubb) - S2 (closure of semilunar valves)
    • S3 and S4 not usually loud enough to be heard
    • Tool: Stethoscope
    • Heart murmur: abnormal sounds sometimes due to valve disorder (e.g., mitral stenosis)

    The Layers of the Heart Wall

    • Endocardium (inner layer): lines chambers and valves, continuous with large blood vessels (thin squamous epithelium)
    • Myocardium (muscle layer): specialized cardiac muscle (95% of wall)
    • Epicardium (external layer): transparent outer layer, part of pericardium

    Pericardium

    • Double walled sac surrounding the heart
    • Space between inner and outer pericardial membranes filled with pericardial fluid
    • Lubrication, prevention of friction during heart beats
    • Pericarditis: inflammation of pericardium
      • Causes surfaces to rub together
      • Distinct scratching sound heard through stethoscope
      • Acute or chronic

    Myocardium

    • Cardiac muscle: muscle fibers swirl/spiral diagonally in interlacing bundles/networks.

    The Heart (Function)

    • Electrical conduction
    • Volume and pressure
    • The muscle cells
    • Stroke volume and cardiac output

    Heart: Electrical Activity, the conducting system

    • Heart has intrinsic rhythmical electrical activity (continuous beating)
    • Specialized cardiac muscle conducting cells (self-excitable)
    • Fire spontaneously due to unstable membrane potential
    • Act as pacemakers; set rhythm
    • Form networks/path for spread of excitation through the heart

    Volume & Pressure: 1. ECG, pressure

    • ECG (electrocardiogram) relates to the electrical activity of the heart over time
    • Pressure is measured in the heart and blood vessels
    • Diagram shows pressure changes relating to the opening and closing of heart valves

    Volume & Pressure: 2. Pressure Detail

    • Pressure in ventricle higher than aortic and pulmonary trunk – SL valves open
    • As ventricle relaxes, pressure drops and AV valves open

    Volume & Pressure: 3. Volume Detail

    • Pressure in atria higher than in ventricle – passive filling (70% ventricular capacity)
    • Volume rises

    Volume & Pressure: 4. Heart Sounds

    • Heart valves closing produce the lubb-dubb sounds

    Myocardium: The Muscle Cells

    • Involuntary contractions
    • Striated, branching fibers
    • Connected by intercalated discs
    • Single central nucleus

    Myocardium: Histology

    • Thick filaments: myosin
    • Thin filaments: actin
    • Contraction: myosin heads pull thin actin filaments, resulting in shortening of the sarcomere
      • Length of individual thin and thick filaments does not change
      • Shortening of sarcomere = shortening of muscle = contraction

    Comparison to Skeletal Muscle

    • Shorter (50-100 µm) and exhibit branching
    • Usually one central nuclei
    • Intercalated discs - contain gap junctions
    • Many more mitochondria
    • Same arrangement (actin, myosin, bands & discs)
    • Less developed sarcoplasmic reticulum with smaller calcium stores

    Stroke Volume

    • End diastolic volume (EDV): volume in ventricle at end of diastole (approximately 130 mL)
    • End systolic volume (ESV): volume in ventricle at end of systole (approximately 60 mL)
    • Stroke volume (SV): volume ejected per beat from each ventricle (approximately 70 mL)
      • SV = EDV - ESV

    Cardiac Output

    • Cardiac output (CO): amount of blood ejected by left ventricle per minute
    • Determined by stroke volume and heart rate (CO = SV x HR)
    • If SV = 70 mL/beat and HR = 75 beats/min, CO = 5250 mL/min
    • Entire blood supply passes through circulatory system every minute
    • Cardiac reserve: maximum output – output at rest (average = X4-5, athlete =X7-8)

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    Description

    This quiz tests your knowledge on the anatomy and function of the heart, including the role of heart valves, myocardial contractions, and circulation. Match heart valve actions to states and answer questions about cardiac health and structure. Perfect for students studying cardiovascular anatomy!

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