Arterial Blood Flow and Peripheral Resistance Quiz
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Questions and Answers

Which equation represents the relationship between arterial pressure, cardiac output, and total peripheral resistance?

  • Arterial pressure = cardiac output + total peripheral resistance
  • Arterial pressure = cardiac output / total peripheral resistance
  • Arterial pressure = cardiac output - total peripheral resistance
  • Arterial pressure = cardiac output x total peripheral resistance (correct)

    • During laminar flow, what type of velocity profile is observed?

  • Parabolic velocity profile (correct)
  • Exponential velocity profile
  • Constant velocity profile
  • Linear velocity profile

    • Which factor is used to determine whether flow is likely to be laminar or turbulent?

  • Reynold's number (Re) (correct)
  • Fluid flow and turbulence
  • Viscosity
  • Poiseuille's law

    • Which of the following is NOT a factor that increases the likelihood of turbulence in blood flow?

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

    What is the equation for Reynold's number (Re)?

    <p>Re = (velocity of flow) x (radius of vessel) / viscosity</p> Signup and view all the answers

    Which statement is true regarding the effect of flow on viscosity?

    <p>Static blood has 100x the viscosity of flowing blood</p> Signup and view all the answers

    What is the primary effect of turbulence on blood flow?

    <p>Turbulence disrupts flow and increases resistance</p> Signup and view all the answers

    According to LaPlace's Law, the tension (T) in a blood vessel wall is proportional to the distending pressure (P) and the radius (R) of the vessel. Which of the following statements is correct?

    <p>The tension (T) in a blood vessel wall is directly proportional to the distending pressure (P) and inversely proportional to the radius (R) of the vessel.</p> Signup and view all the answers

    Which of the following is NOT a practical consequence of LaPlace's Law?

    <p>Regulation of blood flow</p> Signup and view all the answers

    Which of the following is responsible for regulating tissue blood flow in arterioles and precapillary sphincters?

    <p>Smooth muscle control</p> Signup and view all the answers

    What is the purpose of vasomotion in blood vessels?

    <p>To regulate blood flow through capillaries</p> Signup and view all the answers

    What is the term used to describe the increase in blood flow to highly active tissues?

    <p>Active hyperaemia</p> Signup and view all the answers

    What is the term used to describe the increase in blood flow that occurs after a temporary blockage of blood supply?

    <p>Reactive hyperaemia</p> Signup and view all the answers

    Which of the following is responsible for the regulation of arteriolar radius?

    <p>Smooth muscle</p> Signup and view all the answers

    Which of the following is true about blood flow through capillaries?

    <p>It accounts for approximately 5% of total cardiac output at rest.</p> Signup and view all the answers

    Which of the following describes the electrical conduction pathways in cardiac muscle?

    <p>The electrical activity starts in the sinoatrial node and spreads to the ventricles first.</p> Signup and view all the answers

    What is the primary focus of this lecture on cardiac action potentials?

    <p>Depolarization events</p> Signup and view all the answers

    What does an electrocardiogram (ECG) measure?

    <p>The total electrical activity of the heart</p> Signup and view all the answers

    What is the term used to describe the coordinated electrical activity in the heart?

    <p>Functional syncytium</p> Signup and view all the answers

    Which of the following is responsible for modifying the spontaneous electrical activity of the heart?

    <p>Sympathetic and parasympathetic nerves</p> Signup and view all the answers

    How can the spread of electrical activity throughout the heart be measured non-invasively?

    <p>By means of an electrocardiogram (ECG)</p> Signup and view all the answers

    What is the relationship between the shape and features of the ECG and the cellular action potentials?

    <p>The shape and features of the ECG reflect the cellular action potentials.</p> Signup and view all the answers

    Which phase of the cardiac action potential is characterized by rapid depolarization due to an increase in sodium permeability?

    <p>Phase 0</p> Signup and view all the answers

    During which phase of the cardiac action potential do calcium ions enter the cell through L-type channels?

    <p>Phase 2</p> Signup and view all the answers

    What is the effect of elevated internal calcium levels during the cardiac action potential?

    <p>Stimulates opening of potassium channels</p> Signup and view all the answers

    What is the primary effect of sympathetic stimulation on pacemaker activity?

    <p>Increased cAMP production</p> Signup and view all the answers

    How does parasympathetic stimulation affect the membrane potential of pacemaker cells?

    <p>Hyperpolarizes the membrane potential</p> Signup and view all the answers

    What is the intrinsic pacemaker of the heart?

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

    What is the conduction velocity in atrial and ventricular fibers?

    <p>0.3-0.5 m/s</p> Signup and view all the answers

    What does the Q-T interval on an electrocardiogram (ECG) represent?

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

    Which of the following is a possible mechanism of primary hypertension?

    <p>Increased sympathetic system activity</p> Signup and view all the answers

    What are the possible mechanisms of secondary hypertension?

    <p>Renin-angiotensin-aldosterone system dysfunction</p> Signup and view all the answers

    What are the consequences of hypertension?

    <p>All of the above</p> Signup and view all the answers

    How is hypertension treated?

    <p>All of the above</p> Signup and view all the answers

    What type of hypertension affects the pulmonary system?

    <p>Pulmonary hypertension</p> Signup and view all the answers

    Which of the following is NOT a possible contributor to systemic hypertension?

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

    Which of the following is the most potent endogenous vasoconstrictor?

    <p>Endothelin-1 (ET-1)</p> Signup and view all the answers

    Which of the following is responsible for promoting sodium and water excretion in the kidneys?

    <p>Nitric oxide (NO)</p> Signup and view all the answers

    Which of the following is NOT a potential cause of secondary hypertension?

    <p>Primary hypertension</p> Signup and view all the answers

    Which of the following is NOT a consequence of systemic hypertension?

    <p>Increased nitric oxide production</p> Signup and view all the answers

    Which of the following is a major risk factor for cardiovascular disease?

    <p>Increased blood pressure in the arteries of the lungs</p> Signup and view all the answers

    What is the definition of systemic arterial hypertension?

    <p>Systolic blood pressure &gt; 140 mmHg and/or Diastolic blood pressure &gt; 90mmHg</p> Signup and view all the answers

    Which of the following is NOT a possible contributor to systemic hypertension?

    <p>Increased blood pressure in the arteries of the lungs</p> Signup and view all the answers

    Which of the following is responsible for the secretion of aldosterone from the adrenal glands?

    <p>Angiotensin II</p> Signup and view all the answers

    Which of the following is the primary cation in the extracellular fluid (ECF)?

    <p>Sodium (Na+)</p> Signup and view all the answers

    Which of the following is NOT a risk factor for hypertension?

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

    What is the primary cation in the extracellular fluid (ECF)?

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

    Which of the following is responsible for the conversion of angiotensin I to angiotensin II?

    <p>Angiotensin converting enzyme (ACE)</p> Signup and view all the answers

    Which of the following is true about blood flow through capillaries?

    <p>Blood flow is slowest in capillaries compared to other blood vessels.</p> Signup and view all the answers

    What is the primary effect of turbulence on blood flow?

    <p>Increased resistance</p> Signup and view all the answers

    Which of the following is a possible mechanism of primary hypertension?

    <p>Increased sympathetic system activity</p> Signup and view all the answers

    What is the primary effect of turbulence on blood flow?

    <p>Increased resistance</p> Signup and view all the answers

    What is the equation for Reynold's number (Re)?

    <p>Re = (velocity) x (density) x (length) / (viscosity)</p> Signup and view all the answers

    Which of the following is NOT a possible contributor to systemic hypertension?

    <p>Decreased circulating factors</p> Signup and view all the answers

    Which of the following is responsible for promoting sodium and water excretion in the kidneys?

    <p>Renin-angiotensin-aldosterone system (RAAS)</p> Signup and view all the answers

    Which of the following is NOT a risk factor for hypertension?

    <p>Increased sympathetic activity</p> Signup and view all the answers

    Which of the following is the correct order of the cleavage steps in the renin-angiotensin-aldosterone system (RAAS)?

    <p>Angiotensinogen -&gt; Renin -&gt; Angiotensin I -&gt; ACE -&gt; Angiotensin II</p> Signup and view all the answers

    Which of the following is NOT a consequence of hypertension?

    <p>Increased nitric oxide production</p> Signup and view all the answers

    Which of the following is the most potent endogenous vasoconstrictor?

    <p>Endothelin-1 (ET-1)</p> Signup and view all the answers

    Which of the following is NOT a possible mechanism of secondary hypertension?

    <p>Increased sympathetic activity</p> Signup and view all the answers

    Which of the following is NOT a broad category of events that can lead to dysrhythmias?

    <p>Circus re-entry</p> Signup and view all the answers

    Which type of dysrhythmia is considered to be more serious?

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

    Which part of the heart has the fastest inherent rate and acts as the pacemaker?

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

    Which of the following is true about First Degree Heart Block?

    <p>AVN is only slightly affected and conduction is slowed</p> Signup and view all the answers

    What is the most likely consequence of Third Degree Heart Block?

    <p>The ventricles depolarise at their inherent rate</p> Signup and view all the answers

    What can cause the development of ectopic pacemakers in the heart?

    <p>Abnormalities in the conducting system</p> Signup and view all the answers

    Which of the following is NOT a category in the Vaughn-Williams Classification system for anti-dysrhythmic drugs?

    <p>Class IV</p> Signup and view all the answers

    What is the primary effect of the accessory electrical connection between the atria and ventricles in Wolf-Parkinson-White Syndrome?

    <p>Shortening the PR interval</p> Signup and view all the answers

    What is the main characteristic of circuits involved in circus re-entry movements?

    <p>Short length and high impulse frequency</p> Signup and view all the answers

    What is the primary cause of the grey area in the cardiac conduction system?

    <p>Insufficient current generation</p> Signup and view all the answers

    Which of the following is responsible for the conduction of electrical impulses between the atria and ventricles in the heart?

    <p>Bundle of His</p> Signup and view all the answers

    What is the term used to describe a condition where the AV node is only slightly affected and conduction is slowed, resulting in an abnormally long P-R interval?

    <p>First Degree Heart Block</p> Signup and view all the answers

    Which of the following describes a type of second degree heart block where most beats are conducted with a constant P-R interval, but occasionally there is an atrial depolarisation without a ventricular depolarisation?

    <p>Mobitz (type 2)</p> Signup and view all the answers

    Which of the following is NOT a broad category of event that can give rise to dysrhythmias?

    <p>Circus re-entry</p> Signup and view all the answers

    Which of the following is NOT a common type of tachyarrhythmia?

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

    Which part of the heart has the fastest inherent rate and acts as the pacemaker?

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

    Which part of the heart is responsible for generating the impulse that initiates the cardiac action potential?

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

    What is the main characteristic of Wolf-Parkinson-White Syndrome?

    <p>Short PR interval and early upstroke of QRS complex</p> Signup and view all the answers

    What is the primary effect of Class III anti-dysrhythmic drugs?

    <p>Prolong the duration of action potential repolarisation</p> Signup and view all the answers

    What is the effect of unidirectional block in the orthodromic direction?

    <p>Increased frequency of impulses generated</p> Signup and view all the answers

    Study Notes

    Cardiovascular System: Blood Flow and Pressure

    • Arterial pressure (BP) = Cardiac Output (CO) x Total Peripheral Resistance (TPR): This equation describes the relationship between these three key factors in cardiovascular function.

    • Laminar flow: During laminar flow, blood moves in a smooth, layered pattern with the fastest velocity in the center and slower velocity near the vessel walls. This results in a parabolic velocity profile.

    • Reynold's number (Re): This dimensionless quantity is used to predict whether flow will be laminar or turbulent. A higher Re indicates a greater likelihood of turbulent flow.

    • Equation for Reynold's number (Re):

      • Re = (density of fluid x mean velocity x diameter of the vessel) / viscosity of fluid

    • Viscosity and flow: As blood flows through a vessel, its viscosity decreases, making it easier to flow.

    • Effect of turbulence on blood flow: Turbulence increases the energy expenditure of the heart due to increased resistance, and it can also cause damage to blood vessels.

    LaPlace's Law and Vessel Wall Tension

    • LaPlace's Law: This law states that the wall tension (T) in a blood vessel is directly proportional to the distending pressure (P) and the radius (R) of the vessel.

      • T = P x R

    • Practical consequences of LaPlace's Law: - Aneurysms: Weakened vessel walls are more prone to dilation, leading to aneurysms due to increased tension. - Advantages of small vessels: Small vessel radius minimizes wall tension for a given pressure, allowing for efficient blood flow.

    Blood Flow Regulation

    • Vasomotion: This is the rhythmic constriction and dilation of arterioles and precapillary sphincters, which helps regulate blood flow to tissues.

    • Active hyperemia: This is the increase in blood flow to highly active tissues, such as muscles during exercise.

    • Reactive hyperemia: This is the increase in blood flow that occurs after a temporary blockage of blood supply, due to the accumulation of metabolic byproducts and decreased oxygen.

    • Arteriolar radius regulation: The radius of arterioles is regulated by:

      • Myogenic mechanism: Inherent property of vascular smooth muscle to respond to changes in pressure.
      • Metabolic factors: Local changes in tissue metabolism, such as oxygen levels, CO2, pH, and metabolites.
      • Neural control: Sympathetic and parasympathetic nerve activity.
      • Hormonal control: Endocrine hormones like epinephrine and norepinephrine.

    • Blood flow through capillaries: Flow through capillaries is slow, allowing for adequate exchange of nutrients and waste products.

    Electrical Conduction in the Heart

    • Conduction pathways: The electrical activity in cardiac muscle is conducted through a specific pathway:

      • Sinoatrial (SA) node: The pacemaker of the heart.
      • Atrial muscle: The electrical impulse spreads through the atria.
      • Atrioventricular (AV) node: The impulse is delayed here to allow complete atrial contraction.
      • Bundle of His: Conducts the impulse to the ventricles.
      • Purkinje fibers: The impulse rapidly spreads through the ventricular muscle.

    • Cardiac action potential: The lecture focuses on the electrical events that underlie the cardiac action potential, a key aspect of heart function.

    • Electrocardiogram (ECG): This is a non-invasive tool that measures the electrical activity of the heart. It provides valuable diagnostic information about the electrical conduction system of the heart.

    • Syncytium: The coordinated electrical activity in the heart creates a functional syncitium, meaning the cells function as a single unit.

    Modifying Cardiac Electrical Activity

    • Autonomic nervous system: The sympathetic and parasympathetic branches of the autonomic nervous system can modify the spontaneous electrical activity of the heart.

    • Sympathetic stimulation: Increases the rate and force of heart contractions by releasing norepinephrine.

    • Parasympathetic stimulation: Decreases heart rate by releasing acetylcholine.

    • Intrinsic pacemaker: The SA node is the intrinsic pacemaker of the heart, responsible for generating the heart rhythm.

    • Conduction velocity: Conduction velocity is fastest in the Purkinje fibers and slowest in the AV node.

    • ECG interval: The Q-T interval on an ECG reflects the time taken for the ventricles to depolarize and repolarize.

    Hypertension

    • Hypertension: High blood pressure, a major risk factor for cardiovascular disease.

    • Primary hypertension: The cause is unknown, but may involve genetic predisposition and environmental factors.

    • Secondary hypertension: Has a specific identifiable cause, such as kidney disease, endocrine disorders, or medications.

    • Consequences of hypertension:
      - Damage to blood vessels: Hypertension weakens blood vessel walls, leading to atherosclerosis. - Heart disease: Increased workload on the heart, leading to heart failure. - Stroke: Hypertension can lead to rupture of blood vessels in the brain.

    • Treatment of hypertension: Lifestyle modifications and medications are used to manage hypertension.

    • Pulmonary hypertension: Affects the pulmonary arteries and increases pressure in the lungs.

    • Endogenous vasoconstrictor: Angiotensin II is a potent endogenous vasoconstrictor.

    • Renin-angiotensin-aldosterone system (RAAS): This system plays a key role in regulating blood pressure.

    • Aldosterone: This hormone released by the adrenal glands helps retain sodium and water, raising blood pressure.

    • Sodium (Na+): The primary cation in the extracellular fluid.

    Dysrhythmias

    • Dysrhythmias: Disorders of heart rhythm, which can range from mild to life-threatening.

    • Causes of dysrhythmias:

      • Electrolyte imbalances: Imbalances in key electrolytes can disrupt electrical conduction.
      • Structural heart disease: Heart conditions, such as cardiomyopathy, can affect electrical activity.
      • Ischemia: Lack of blood flow to the heart muscle can cause electrical disturbances.
      • Drugs: Certain medications can cause dysrhythmias.

    • Types of dysrhythmias:

      • Bradyarrhythmias: Slow heart rate.
      • Tachyarrhythmias: Fast heart rate.

    • First degree heart block: A delay in the conduction of the electrical impulse through the AV node, resulting in a prolonged PR interval on the ECG.

    • Third degree heart block: Complete blockage of conduction between the atria and ventricles, resulting in the atria and ventricles beating independently.

    • Ectopic pacemakers: Abnormal pacemakers that develop in areas other than the SA node, causing an irregular heartbeat.

    • Wolf-Parkinson-White Syndrome: A condition where an accessory electrical connection bypasses the AV node, shortening the PR interval and creating a delta wave on the ECG.

    • Re-entry arrhythmias: Occur when an electrical impulse travels in a loop, circling around the heart.

    • Vaughn-Williams classification system: Categorizes anti-dysrhythmic drugs based on their mechanisms of action.

    • Unidirectional block: A type of block that occurs in one direction, allowing the impulse to pass in the opposite direction.

    • Orthodromic conduction: When the impulse travels from the atrium to the ventricle through the AV node.

    • Second degree heart block (Mobitz I): This type of block shows gradual prolongation of the PR interval until a beat fails to conduct.

    • Second degree heart block (Mobitz II): Regular P waves are seen, but some don't have associated QRS complexes. There's a consistent P-R interval before those missing beats.

    • Tachycardia (SVT): A rapid heart rate exceeding 100 bpm.

    • SA node: Sets the heart's rhythm and initiates the action potential.

    • Class III anti-dysrhythmic drugs: They prolong the duration of the action potential, thus preventing rapid firing.

    • Effect of unidirectional block in the orthodromic direction: In the orthodromic direction, a blocked wave can circulate back through the accessory pathway, causing tachycardia.

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    Description

    Test your knowledge on arterial blood flow and peripheral resistance in the vasculature with this quiz. Learn about factors affecting resistance to blood flow, regulation of tissue blood flow, and the role of capillaries. Challenge yourself with questions on fluid flow and the parabolic velocity profile during laminar flow.

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