Heart Circulation and Valves Quiz

The pulmonary trunk transports deoxygenated blood from the right ventricle to the lungs.

The two sets are the atrioventricular (AV) valves located between the atria and ventricles, and the semilunar valves located at the boundary between each ventricle and its associated arterial trunk.

The aortic semilunar valve is located between the left ventricle and the aorta, allowing oxygenated blood to flow into the systemic circulation and preventing backflow.

<p>The pulmonary arteries are unique because they carry deoxygenated blood, unlike other arteries that generally carry oxygenated blood.</p> Signup and view all the answers

<p>Pulmonary circulation refers to the movement of blood to and from the lungs for gas exchange, which is vital for oxygenating blood.</p> Signup and view all the answers

<p>The blood flows from the right atrium to the right ventricle, then through the pulmonary semilunar valve to the pulmonary artery and into the lungs.</p> Signup and view all the answers

<p>Systemic circulation involves the movement of oxygenated blood to the body, while pulmonary circulation involves the movement of deoxygenated blood to the lungs.</p> Signup and view all the answers

<p>Clinical signs include systemic edema, characterized by swelling in body tissues such as legs, ankles, and feet.</p> Signup and view all the answers

<p>It is important because it replenishes the oxygen supply of blood before it is pumped into the systemic circulation.</p> Signup and view all the answers

<p>Left ventricle impairment leads to pulmonary edema, causing fluid accumulation in the lungs and potential breathing difficulties.</p> Signup and view all the answers

<p>Arteries, veins, and capillaries.</p> Signup and view all the answers

<p>The heart is located posterior to the sternum and between the lungs.</p> Signup and view all the answers

<p>To transport deoxygenated blood from the right side of the heart to the lungs for gas exchange and return oxygenated blood to the left atrium.</p> Signup and view all the answers

<p>To pump blood throughout the body, providing oxygen and nutrients while removing wastes.</p> Signup and view all the answers

<p>Oxygenated blood enters the left atrium, passes through the left AV valve into the left ventricle, and is then pumped through the aortic semilunar valve into the aorta.</p> Signup and view all the answers

<p>Heart valves prevent backflow of blood.</p> Signup and view all the answers

<p>The pericardium consists of the fibrous pericardium, which is dense connective tissue, and the serous pericardium, which has parietal and visceral layers made of simple squamous epithelium and areolar connective tissue.</p> Signup and view all the answers

<p>Capillaries are the sites of exchange between blood and body cells.</p> Signup and view all the answers

<p>The heart is rotated such that the right side is more anteriorly positioned, while the left atrium and left ventricle are positioned more posteriorly.</p> Signup and view all the answers

<p>The pericardial cavity contains serous fluid that reduces friction between the heart and surrounding structures, allowing for smooth cardiac movement.</p> Signup and view all the answers

<p>The SA node (sinoatrial node) initiates the action potential.</p> Signup and view all the answers

<p>Deoxygenated blood drains into the superior vena cava, inferior vena cava, and coronary sinus, then enters the right atrium.</p> Signup and view all the answers

<p>The heart muscle is unable to respond to new stimuli after contraction.</p> Signup and view all the answers

<p>The right side receives deoxygenated blood, while the left side receives oxygenated blood.</p> Signup and view all the answers

<p>The right and left pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs for gas exchange in the pulmonary capillaries.</p> Signup and view all the answers

<p>Systemic circulation delivers oxygenated blood from the left side of the heart to the body cells, while pulmonary circulation carries deoxygenated blood from the right side of the heart to the lungs.</p> Signup and view all the answers

<p>A myocardial infarction is a blockage that restricts blood flow to the heart muscle.</p> Signup and view all the answers

<p>The fibrous pericardium provides a sturdy barrier that protects the heart from external forces and prevents overexpansion.</p> Signup and view all the answers

<p>Arteries have thicker walls to withstand higher pressure, while veins have thinner walls.</p> Signup and view all the answers

<p>The heart is conical and about the size of a clenched fist, which optimizes its ability to pump blood efficiently throughout the body.</p> Signup and view all the answers

<p>Cardiac output is the volume of blood the heart pumps per minute; it's crucial for delivering sufficient blood flow to organs.</p> Signup and view all the answers

<p>Consequences include tissue deprivation of oxygen, nutrient accumulation, and potential cell death.</p> Signup and view all the answers

<p>The superior vena cava (SVC) and inferior vena cava (IVC).</p> Signup and view all the answers

<p>The heart is a hollow, four-chambered organ that contracts to pump blood effectively.</p> Signup and view all the answers

<p>Shortness of breath, chest pain, and fainting.</p> Signup and view all the answers

<p>Hypertrophic cardiomyopathy involves an inward growth of the heart walls leading to decreased cardiac output, while cardiomegaly is a general term for an enlarged heart without specifying the structural changes.</p> Signup and view all the answers

<p>Heart sounds provide clinically important information about heart activity and the action of heart valves.</p> Signup and view all the answers

<p>Valvular insufficiency causes the cardiac valves to leak, resulting in heart murmurs which can indicate problems with heart function.</p> Signup and view all the answers

<p>An ultrasound or echocardiogram.</p> Signup and view all the answers

<p>The pericardium covers the heart and consists of the fibrous pericardium, visceral pericardium, and parietal pericardium.</p> Signup and view all the answers

<p>The pericardial cavity is located between the visceral and parietal layers of the serous pericardium and contains serous fluid to minimize friction.</p> Signup and view all the answers

<p>The left atrium is connected to the left pulmonary veins from an anterior view.</p> Signup and view all the answers

<p>Excess fluid accumulation can limit the heart's movement and lead to cardiac tamponade, preventing the heart chambers from filling adequately.</p> Signup and view all the answers

<p>The myocardium is responsible for the contraction of the heart.</p> Signup and view all the answers

<p>The interventricular sulcus and the posterior interventricular sulcus separate the ventricles from each other.</p> Signup and view all the answers

<p>Pericarditis is the inflammation of the pericardium and is associated with a friction rub heard with a stethoscope.</p> Signup and view all the answers

<p>The epicardium is the outermost layer of the heart wall and is also called the visceral pericardium.</p> Signup and view all the answers

<p>The ascending aorta, aortic arch, superior vena cava, pulmonary trunk, and right and left ventricles are visible from the anterior view.</p> Signup and view all the answers

<p>The coronary sulcus separates the atria from the ventricles and contains the left and right coronary arteries.</p> Signup and view all the answers

<p>The myocardium generates the force necessary to pump blood.</p> Signup and view all the answers

<p>The left ventricular wall is typically three times thicker than the right ventricular wall.</p> Signup and view all the answers

<p>The fossa ovalis is a depression in the interatrial septum marking the location of the fetal foramen ovale.</p> Signup and view all the answers

<p>Deoxygenated blood enters through the superior and inferior venae cava into the right atrium, while oxygenated blood enters the left atrium from the lungs.</p> Signup and view all the answers

<p>Papillary muscles anchor the tendinous cords that secure the atrioventricular valves to prevent backflow during ventricular contraction.</p> Signup and view all the answers

<p>The atrioventricular valves prevent backflow into the atria during ventricular contraction.</p> Signup and view all the answers

<p>Cardiomegaly is characterized by an enlargement of the heart due to an increase in chamber or wall size.</p> Signup and view all the answers

<p>Semilunar valves have cusps that resemble half-moons and allow blood to flow from the ventricles into the aorta and pulmonary trunk.</p> Signup and view all the answers

<p>The interatrial septum separates the left and right atria.</p> Signup and view all the answers

<p>The flexibility and elasticity of heart valves decrease, potentially leading to inflexibility and altered blood flow.</p> Signup and view all the answers

<p>Trabeculae carneae are large, smooth, irregular muscular ridges found in the ventricles.</p> Signup and view all the answers

<p>The two types of heart valves are atrioventricular valves (between atria and ventricles) and semilunar valves (between ventricles and arterial trunks).</p> Signup and view all the answers

<p>Hypertrophic cardiomyopathy is characterized by thickening of the heart muscle.</p> Signup and view all the answers

<p>Tendinous cords secured by papillary muscles prevent the AV valves from being forced back into the atria.</p> Signup and view all the answers

<p>The RMP of -60 mV is important as it indicates the threshold at which SA nodal cells can initiate spontaneous depolarization, essential for maintaining the heart's rhythm.</p> Signup and view all the answers

<p>Voltage-gated Ca2+ channels open during depolarization, allowing Ca2+ to enter the cell, which is crucial for reaching the threshold and initiating an action potential.</p> Signup and view all the answers

<p>Continuous parasympathetic stimulation by the vagus nerve decreases the inherent heart rate of SA nodal cells to a normal resting rate of 75 beats per minute.</p> Signup and view all the answers

<p>During repolarization, K+ channels open, allowing K+ to flow out of the cell, which brings the membrane potential back to -60 mV, the resting membrane potential.</p> Signup and view all the answers

<p>Autorhythmicity is the ability of SA nodal cells to spontaneously depolarize and generate action potentials without external stimuli, which is essential for heart rhythm stability.</p> Signup and view all the answers

<p>Unlike neurons that require external stimuli to depolarize, SA nodal cells generate action potentials autonomously through their pacemaker potentials.</p> Signup and view all the answers

<p>The fibrous skeleton insulates parts of the heart, slowing the conduction rate of action potentials and acting as a 'bottleneck' to coordinate heart contractions.</p> Signup and view all the answers

<p>Ectopic pacemakers are alternate sites within the heart that can initiate action potentials but do so at a slower rate compared to the SA node.</p> Signup and view all the answers

<p>Pacemaker potentials are gradual increases in membrane potential that allow SA nodal cells to reach threshold potential and depolarize, initiating heartbeats.</p> Signup and view all the answers

<p>The intrinsic heart rate is approximately 100 beats per minute, which is modified to 75 beats per minute through parasympathetic stimulation.</p> Signup and view all the answers

<p>The SA node establishes the heart rhythm at 60 to 100 beats per minute.</p> Signup and view all the answers

<p>The AV node takes over as the pacemaker, establishing a slower rhythm of 40 to 50 beats per minute.</p> Signup and view all the answers

<p>It begins at the SA node, travels through the AV node, AV bundle, bundle branches, and Purkinje fibers.</p> Signup and view all the answers

<p>It allows the ventricles to fill adequately before contraction, preventing backflow into the atria.</p> Signup and view all the answers

<p>-90 mV.</p> Signup and view all the answers

<p>The opening of fast voltage-gated Na+ channels allows Na+ to enter the cell.</p> Signup and view all the answers

<p>The plateau phase is when the membrane potential remains at +30 mV due to the slow influx of Ca2+ and K+ exiting.</p> Signup and view all the answers

<p>Calcium ions bind to troponin, initiating crossbridge cycling and muscle contraction.</p> Signup and view all the answers

<p>Depolarization, plateau, and repolarization.</p> Signup and view all the answers

<p>The refractory period is the time when cardiac muscle cells cannot respond to a new action potential.</p> Signup and view all the answers

<p>Mechanical pacemakers deliver electrical impulses to maintain heart rhythm, compensating for natural pacemaker failure.</p> Signup and view all the answers

<p>The slow influx of Ca2+ and the exit of K+ keep the cell in a depolarized state with no electrical change.</p> Signup and view all the answers

<p>They include the release of Ca2+ from the SR, binding to troponin, and the sliding of actin and myosin filaments.</p> Signup and view all the answers

<p>It involves the exit of K+ from the cell and the closure of Ca2+ channels, returning the membrane potential to -90 mV.</p> Signup and view all the answers

<p>The plateau phase prolongs contraction time, ensuring that the heart pumps effectively without tetany.</p> Signup and view all the answers

<p>Dense irregular connective tissue.</p> Signup and view all the answers

<p>Coronary arteries transport oxygenated blood to the heart, while coronary veins carry deoxygenated blood away from the heart.</p> Signup and view all the answers

<p>It can lead to a myocardial infarction, commonly known as a heart attack.</p> Signup and view all the answers

<p>The great cardiac vein, middle cardiac vein, and small cardiac vein.</p> Signup and view all the answers

<p>The coronary sinus collects deoxygenated blood from the myocardium and empties it into the right atrium.</p> Signup and view all the answers

<p>They do not anastomose with each other.</p> Signup and view all the answers

<p>Valvular stenosis is the narrowing of a heart valve, often caused by scarring or decreased valve flexibility.</p> Signup and view all the answers

<p>It occurs when blood flow to a part of the heart is blocked, often by a blood clot.</p> Signup and view all the answers

<p>Women may experience jaw pain or flulike symptoms.</p> Signup and view all the answers

<p>It interrupts blood flow to the heart muscle.</p> Signup and view all the answers

<p>They provide mechanical anchoring and facilitate electrical connections between cardiac muscle cells.</p> Signup and view all the answers

<p>The SA node is the heart's pacemaker, regulating heart rate through electrical impulses.</p> Signup and view all the answers

<p>Myoglobin binds oxygen, providing it to the muscle during rest.</p> Signup and view all the answers

<p>Cardiac muscle primarily relies on aerobic respiration, while skeletal muscle can also utilize anaerobic pathways.</p> Signup and view all the answers

<p>The SA node initiates the heartbeat while the AV node transmits the electrical signals from the atria to the ventricles.</p> Signup and view all the answers

<p>Parasympathetic innervation decreases heart rate, whereas sympathetic innervation increases both heart rate and force of contraction.</p> Signup and view all the answers

<p>Baroreceptors detect changes in blood pressure and help regulate heart rate and blood vessel diameter to maintain homeostasis.</p> Signup and view all the answers

<p>The three phases are reaching threshold, depolarization, and repolarization.</p> Signup and view all the answers

<p>The unstable RMP is maintained by K+ leak channels, Na+ leak channels, and Na+/K+ pumps.</p> Signup and view all the answers

<p>The cardiac center modifies cardiac activity by integrating signals from both the sympathetic and parasympathetic nervous systems.</p> Signup and view all the answers

<p>During depolarization, voltage-gated Ca2+ channels open, causing the membrane potential to shift from -40 mV to a positive value.</p> Signup and view all the answers

<p>Ischemic conditions can lead to cardiac muscle failure due to the muscle's limited ability to perform glycolysis and sustain oxygen debt.</p> Signup and view all the answers

<p>Purkinje fibers conduct the electrical impulse to the outer regions of the ventricles, facilitating coordinated contraction.</p> Signup and view all the answers

<p>Sympathetic innervation causes dilation of coronary arteries, increasing blood flow, while parasympathetic innervation has little effect on coronary artery diameter.</p> Signup and view all the answers

<p>Cardiac muscle cells primarily rely on aerobic cellular respiration for energy due to their high demand for sustained contraction.</p> Signup and view all the answers

<p>Voltage-gated channels allow for the controlled flow of ions like Na+ and Ca2+, facilitating the depolarization and repolarization needed for action potential generation.</p> Signup and view all the answers

<p>Repolarization involves closing of calcium channels and opening of potassium channels, returning the membrane potential to -60 mV.</p> Signup and view all the answers

<p>The cardiac center increases heart rate and contractility during stress, ensuring sufficient blood flow and oxygen delivery to meet heightened demands.</p> Signup and view all the answers

<p>The five phases are atrial relaxation and ventricular filling, atrial contraction and ventricular filling, isovolumic contraction, ventricular ejection, and isovolumic relaxation.</p> Signup and view all the answers

<p>Pressure changes in the atria and ventricles cause the AV valves to open for blood flow into the ventricles, and pressure in the ventricles opens the semilunar valves for blood ejection into the arteries.</p> Signup and view all the answers

<p>The end-diastolic volume (EDV) is crucial as it represents the maximum blood volume in the ventricles at the end of diastole, influencing stroke volume and cardiac output.</p> Signup and view all the answers

<p>Isovolumic contraction is when the ventricles contract with no change in blood volume, critical for building pressure to eventually open the semilunar valves.</p> Signup and view all the answers

<p>Atrial systole contracts the atria to push remaining blood into the ventricles through the open AV valves, ensuring efficient ventricular filling.</p> Signup and view all the answers

<p>Isovolumic relaxation occurs when the ventricles relax without changing volume, as both semilunar and AV valves are closed, preparing the heart for the next filling phase.</p> Signup and view all the answers

<p>During ventricular ejection, the semilunar valves open due to increased pressure, allowing blood to be pumped into the arteries, which is vital for systemic circulation.</p> Signup and view all the answers

<p>Contraction of the atria compresses the openings for the great veins, preventing backflow of blood into the veins during ventricular contraction.</p> Signup and view all the answers

<p>Stroke volume (SV) is the amount of blood ejected during ventricular contraction, while end-systolic volume (ESV) represents the volume of blood remaining in the ventricle at the end of contraction.</p> Signup and view all the answers

<p>The semilunar valves open during ventricular ejection to allow blood to flow into the arteries and close during isovolumic relaxation to prevent backflow.</p> Signup and view all the answers

<p>Semilunar valves open when ventricular pressure exceeds arterial pressure, allowing blood to flow into the arterial trunks.</p> Signup and view all the answers

<p>It may result in edema due to fluid accumulation.</p> Signup and view all the answers

<p>Cardiac output is calculated using heart rate (HR) and stroke volume (SV).</p> Signup and view all the answers

<p>The dicrotic notch represents a temporary drop in pressure that occurs when the aortic semilunar valve closes.</p> Signup and view all the answers

<p>The left ventricle is larger and stronger than the right ventricle to pump blood through the systemic circulation.</p> Signup and view all the answers

<p>The cardiac cycle includes phases of atrial relaxation, atrial contraction, isovolumic contraction, ventricular ejection, and isovolumic relaxation.</p> Signup and view all the answers

<p>All heart valves are closed simultaneously, and the volume of blood in the ventricles remains unchanged.</p> Signup and view all the answers

<p>Cardiac reserve is determined by subtracting resting cardiac output from cardiac output during exercise.</p> Signup and view all the answers

<p>The P wave represents atrial depolarization during the cardiac cycle.</p> Signup and view all the answers

<p>The AV valves open and close due to the pressure differences between the atria and ventricles.</p> Signup and view all the answers

<p>Individuals with smaller hearts have higher resting heart rates to maintain normal cardiac output.</p> Signup and view all the answers

<p>Stroke volume indicates the volume of blood ejected from the ventricles during one heartbeat.</p> Signup and view all the answers

<p>With a cardiac output of approximately 5 L per minute, the total blood volume is circulated every minute, equating to over 7000 L daily.</p> Signup and view all the answers

<p>Systemic circulation requires a greater muscular contraction from the left ventricle compared to the right ventricle for pulmonary circulation.</p> Signup and view all the answers

<p>ATP binds to the myosin head to release it from actin and is then split by myosin ATPase to reset the head.</p> Signup and view all the answers

<p>The longer refractory period in cardiac muscle cells is due to an extended plateau in the action potential, preventing tetany.</p> Signup and view all the answers

<p>The three principal deflections are the P wave, QRS complex, and T wave.</p> Signup and view all the answers

<p>Ca2+ channel blockers decrease the force of contraction and slow the heart rate by blocking calcium entry into cardiac cells.</p> Signup and view all the answers

<p>The P-R interval measures the time from the start of the P wave to the beginning of the QRS complex, reflecting AV node conduction.</p> Signup and view all the answers

<p>A third-degree AV block results in complete failure to conduct atrial action potentials to the ventricles, which can be life-threatening.</p> Signup and view all the answers

<p>The T wave represents ventricular repolarization, indicating the recovery phase of the ventricles after contraction.</p> Signup and view all the answers

<p>Ventricular fibrillation involves chaotic electrical activity in the ventricles, leading to uncoordinated muscle contraction and possible loss of consciousness.</p> Signup and view all the answers

<p>The cardiac cycle consists of distinct phases that include atrial relaxation, ventricular filling, contraction, and relaxation.</p> Signup and view all the answers

<p>High-frequency stimulation causes sustained muscle contraction, or tetany, due to the short refractory period of skeletal muscle.</p> Signup and view all the answers

<p>The AV node delays the electrical signal from the atria before it travels to the ventricles, allowing for coordinated contractions.</p> Signup and view all the answers

<p>The Q-T interval measures the time from the beginning of the QRS complex to the end of the T wave, and a longer interval may indicate significant arrhythmias or other cardiac issues.</p> Signup and view all the answers

<p>Abnormal waves or segments, such as a flattened T wave, can indicate issues like ischemia or other heart dysfunctions.</p> Signup and view all the answers

<p>An AED can quickly restore a normal heart rhythm in cases of ventricular fibrillation, enhancing survival chances during cardiac emergencies.</p> Signup and view all the answers

<p>It can lead to cyanosis or other symptoms due to the mixing of oxygenated and deoxygenated blood.</p> Signup and view all the answers

<p>They decrease the contractility of the heart and dilate blood vessels.</p> Signup and view all the answers

<p>Intercalated discs facilitate coordinated contraction of the heart by connecting cardiac muscle cells.</p> Signup and view all the answers

<p>Atria have thinner walls than ventricles due to lower pressure and shorter distances for blood transport.</p> Signup and view all the answers

<p>Coronary vessels supply the heart muscle with oxygen and nutrients essential for its function.</p> Signup and view all the answers

<p>It can increase heart rate due to the loss of parasympathetic input.</p> Signup and view all the answers

<p>The right ventricle has a thinner wall than the left ventricle because it pumps blood to the lungs, which have lower resistance.</p> Signup and view all the answers

<p>Common symptoms include chest pain and pain radiating to the arm and jaw.</p> Signup and view all the answers

<p>Bradycardia decreases heart rate, which consequently reduces cardiac output.</p> Signup and view all the answers

<p>The four chambers of the heart develop from a single primitive heart tube during early embryonic development.</p> Signup and view all the answers

<p>Pericardial fluid lubricates the surfaces between the pericardial layers to reduce friction during heartbeats.</p> Signup and view all the answers

<p>An incomplete partition in the interatrial septum can lead to an atrial septal defect.</p> Signup and view all the answers

<p>The right side of the heart is more visible from the anterior view, while the left side is more visible from the posterior view.</p> Signup and view all the answers

<p>The atrioventricular valves separate the atria from the ventricles.</p> Signup and view all the answers

<p>Intercalated discs link cardiac muscle cells together and permit action potential passage.</p> Signup and view all the answers

<p>The SA node initiates an action potential that spreads through the conduction system, resulting in a heartbeat.</p> Signup and view all the answers

<p>If the foramen ovale remains open, blood flows from the right atrium to the left atrium.</p> Signup and view all the answers

<p>Coronary arteries supply blood to the heart wall.</p> Signup and view all the answers

<p>Inadequate oxygen supply can lead to cardiac muscle cell failure.</p> Signup and view all the answers

<p>Desmosomes provide strong adhesion between cardiac muscle cells.</p> Signup and view all the answers

<p>Tetralogy of Fallot involves an uneven division of the truncus arteriosus by the aorticopulmonary septum.</p> Signup and view all the answers

<p>Sympathetic stimulation increases heart rate by releasing norepinephrine and epinephrine, which bind to β-adrenergic receptors, enhancing the firing rate of the SA node.</p> Signup and view all the answers

<p>Chronotropic agents are external factors that affect heart rate; positive agents increase it while negative agents decrease it.</p> Signup and view all the answers

<p>The Frank-Starling law states that increased preload leads to increased stroke volume due to greater stretch of heart muscle before contraction.</p> Signup and view all the answers

<p>Preload, afterload, and the force of contraction of the myocardium are key factors influencing stroke volume.</p> Signup and view all the answers

<p>Inotropic agents alter the force of contraction of the myocardium, with positive agents increasing and negative agents decreasing it.</p> Signup and view all the answers

<p>Higher afterload decreases stroke volume because the heart must work harder to pump blood against increased resistance.</p> Signup and view all the answers

<p>Thyroid hormones enhance heart rate by making SA nodal cells more responsive to norepinephrine and epinephrine.</p> Signup and view all the answers

<p>Sympathetic nerve stimulation increases calcium influx in AV node cells, reducing conduction delay and raising heart rate.</p> Signup and view all the answers

<p>Venous return directly affects preload; an increase in venous return raises preload, enhancing stroke volume.</p> Signup and view all the answers

<p>An increase in afterload leads to a decrease in stroke volume as the heart faces more resistance during contraction.</p> Signup and view all the answers

<p>Positive chronotropic agents increase heart rate, while negative chronotropic agents decrease it.</p> Signup and view all the answers

<p>Individuals with a weakened heart may have reduced cardiac reserve due to limited ability to increase heart rate and stroke volume under stress.</p> Signup and view all the answers

<p>An increase in preload enhances myocardial contraction strength due to better overlap of actin and myosin filaments.</p> Signup and view all the answers

<p>Highly trained athletes may experience up to seven-fold increases in adrenal medulla secretion compared to nonathletic individuals.</p> Signup and view all the answers

<p>Cardiac output is the product of heart rate and stroke volume, meaning an increase in either factor results in greater overall blood flow.</p> Signup and view all the answers

<p>Decreased stroke volume can lead to reduced cardiac output, which negatively impacts tissue perfusion and oxygen delivery.</p> Signup and view all the answers

<p>Cations, primarily Na+ and Ca2+, enter the SA nodal cells through open voltage-gated cation channels.</p> Signup and view all the answers

<p>The action potential travels through the SA node, AV node, AV bundle, bundle branches, and Purkinje fibers.</p> Signup and view all the answers

<p>Preload is the measure of the stretch of the heart chamber before contraction, and it is directly correlated with stroke volume.</p> Signup and view all the answers

<p>Positive inotropic agents increase stroke volume by enhancing the contractility of cardiac muscle.</p> Signup and view all the answers

<p>Cardiac muscle cells exhibit a longer refractory period than skeletal muscle fibers.</p> Signup and view all the answers

<p>Positive chronotropic agents increase the heart rate by enhancing the activity of the SA and AV nodes.</p> Signup and view all the answers

<p>The foramen ovale allows most of the blood to bypass pulmonary circulation while in the embryo.</p> Signup and view all the answers

<p>The phases are atrial contraction and ventricular filling, isovolumetric contraction, and ventricular ejection.</p> Signup and view all the answers

<p>During the atrial reflex, there is a decrease in the filling rate of the atria to control heart rate.</p> Signup and view all the answers

<p>Chronotropic agents can be positive, increasing heart rate, or negative, decreasing heart rate.</p> Signup and view all the answers

<p>The mechanical events involve crossbridge cycling and the shortening of sarcomeres.</p> Signup and view all the answers

<p>Calcium channels in SA nodal cells allow for depolarization, which initiates action potentials.</p> Signup and view all the answers

<p>Increased venous return leads to greater stroke volume due to enhanced preload on the heart.</p> Signup and view all the answers

<p>An electrocardiogram (ECG) is used to record the electrical changes in the heart.</p> Signup and view all the answers

<p>Increased venous return leads to increased cardiac output due to enhanced stroke volume.</p> Signup and view all the answers

<p>Positive inotropic agents increase cardiac output by enhancing the force of heart contractions.</p> Signup and view all the answers

<p>Higher afterload decreases stroke volume as it creates more resistance for the ventricles to eject blood.</p> Signup and view all the answers

<p>Venous return can approximately double during exercise compared to its rate at rest.</p> Signup and view all the answers

<p>Greater venous pressure and a slower heart rate contribute to increased venous return.</p> Signup and view all the answers

<p>Electrolyte imbalances such as increased levels of K+ or H+ act as negative inotropic agents, decreasing cardiac output.</p> Signup and view all the answers

<p>Atherosclerosis increases resistance in arteries, thereby increasing afterload and decreasing stroke volume and cardiac output.</p> Signup and view all the answers

<p>Chronotropic agents influence the heart rate by acting on the SA and AV nodes to speed up or slow down the heartbeat.</p> Signup and view all the answers

<p>Increased Ca2+ concentrations enhance myocardial contractility by increasing the formation of crossbridges.</p> Signup and view all the answers

<p>Bradycardia is defined as a resting heart rate below 60 beats per minute, which can lead to reduced cardiac output.</p> Signup and view all the answers

<p>By day 21 of embryonic development, paired heart tubes fuse to form a single primitive heart tube.</p> Signup and view all the answers

<p>The net effect on cardiac output is determined by the relative changes in both stroke volume and heart rate.</p> Signup and view all the answers

<p>Stroke volume is influenced by venous return, inotropic agents, and afterload.</p> Signup and view all the answers

<p>Positive inotropic agents increase contractility, while negative inotropic agents decrease contractility.</p> Signup and view all the answers