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CV System - Medium
40 Questions
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CV System - Medium

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@AccomplishedLongBeach

Questions and Answers

What effect does the dorsal motor nucleus of the vagus nerve have on heart rate?

  • Increases heart rate
  • Has no effect on heart rate
  • Decreases heart rate (correct)
  • Irregularly changes heart rate

    • The sympathetic nervous system typically increases heart rate.

    True

    Which part of the nervous system decreases heart rate?

    Parasympathetic nervous system

    The _____ node is known as the natural pacemaker of the heart.

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

    Match the cardiac components with their functions:

    <p>SA node = Natural pacemaker AV node = Delays impulse to ventricles Sympathetic trunk ganglion = Increases heart rate Parasympathetic neurons = Decreases heart rate</p> Signup and view all the answers

    Which process causes the rising phase of the action potential in cardiac muscle cells?

    <p>Influx of Na+ via fast voltage-gated channels</p> Signup and view all the answers

    Cardiac muscle action potentials do not have a plateau phase.

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

    What is the primary function of contractile muscle fibers in the heart?

    <p>Pumping action of the heart</p> Signup and view all the answers

    What is the primary function of the sympathetic nervous system in regulating heart rate during stress?

    <p>Increases heart rate and contractility</p> Signup and view all the answers

    Epinephrine decreases heart rate and contractility.

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

    What neurotransmitter is released by the parasympathetic nervous system to slow heart rate?

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

    Hyperkalemia can lead to ______ and cardiac arrest.

    <p>heart block</p> Signup and view all the answers

    Match the following ions with their effects on heart function:

    <p>Calcium (Ca2+) = Increased HR and contractility Potassium (K+) = Alters electrical activity Hypocalcemia = Depresses heart function Hyperkalemia = Leads to feeble heartbeat</p> Signup and view all the answers

    What will happen to the end-diastolic volume (EDV) when the heart rate increases due to sympathetic activation?

    <p>EDV decreases due to decreased fill time</p> Signup and view all the answers

    Thyroxine has no significant effect on heart rate.

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

    What is the role of norepinephrine in heart rate regulation?

    <p>It binds to β1-adrenergic receptors, increasing heart rate and contractility.</p> Signup and view all the answers

    What is the cardiac output (CO) when heart rate (HR) is 75 beats/min and stroke volume (SV) is 70 ml/beat?

    <p>5.25 L/min</p> Signup and view all the answers

    The stroke volume (SV) correlates with the volume of blood pumped out by one ventricle with each beat.

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

    What is the average heart rate (HR) at rest?

    <p>75 beats/min</p> Signup and view all the answers

    Cardiac output (CO) can be calculated using the formula CO = HR × ______.

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

    Which of the following factors does NOT affect cardiac output (CO)?

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

    Match the following cardiovascular terms with their definitions:

    <p>Heart Rate (HR) = Number of beats per minute Stroke Volume (SV) = Volume of blood pumped by one ventricle per beat Cardiac Output (CO) = Amount of blood pumped out by each ventricle in one minute End Diastolic Volume (EDV) = Volume of blood in the ventricles at the end of filling</p> Signup and view all the answers

    Preload refers to the amount of blood remaining in the ventricle after contraction.

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

    What is the total blood flow at rest?

    <p>6000 ml/min</p> Signup and view all the answers

    What is systolic pressure?

    <p>Pressure when sounds first occur as blood starts to spurt through the artery</p> Signup and view all the answers

    Diastolic pressure is normally less than 100 mm Hg.

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

    Name one artery associated with the lower limb.

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

    The _____ artery is responsible for supplying blood to the forearm.

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

    Match the following arterial terms with their descriptions:

    <p>Superficial temporal artery = Artery of the head Posterior tibial artery = Artery supplying the back of the lower leg Popliteal artery = Artery behind the knee Radial artery = Artery supplying the forearm and hand</p> Signup and view all the answers

    What does MAP stand for in relation to blood pressure?

    <p>Mean Arterial Pressure</p> Signup and view all the answers

    Peripheral resistance is mainly affected by vessel diameter.

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

    What is the relationship between blood pressure and cardiac output?

    <p>Blood pressure varies directly with cardiac output.</p> Signup and view all the answers

    What is the main function of the cardioacceleratory center?

    <p>To increase cardiac output</p> Signup and view all the answers

    The baroreceptor reflex helps to increase blood pressure when it is high.

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

    What are the two main types of regulation for blood pressure?

    <p>Short-term regulation and long-term regulation</p> Signup and view all the answers

    The ________ center of the medulla oblongata is responsible for cardiovascular regulation.

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

    Which statement best describes the function of the vasomotor center?

    <p>It controls vasoconstriction and vasodilation</p> Signup and view all the answers

    Chemoreceptor reflexes play a role in the short-term regulation of blood pressure.

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

    What happens to cardiac output when blood pressure falls?

    <p>Cardiac output increases.</p> Signup and view all the answers

    Match the following types of regulation with their descriptions:

    <p>Short-term regulation = Involves neural mechanisms and hormonal control Long-term regulation = Primarily managed by renal controls Baroreceptor reflexes = Responds to changes in mean arterial pressure Vasomotor control = Regulates blood vessel diameter</p> Signup and view all the answers

    Study Notes

    Nervous System Control of Heart Rate

    • The autonomic nervous system regulates heart rate through sympathetic and parasympathetic pathways.
    • The dorsal motor nucleus of the vagus nerve decreases heart rate via the cardioinhibitory center.
    • Sympathetic cardiac nerves increase heart rate and myocardial contractility.

    Cardiac Muscle Action Potentials

    • Contractile cardiac muscle fibers are responsible for the heart's pumping action, featuring plateau phases in action potentials.
    • Fast voltage-gated Na+ channels open during depolarization, causing an influx of Na+, leading to the rising phase of the action potential.

    Cardiac Output (CO)

    • CO is defined as the volume of blood pumped by each ventricle per minute: CO = heart rate (HR) × stroke volume (SV).
    • At rest, an average CO is approximately 5.25 L/min, calculated with a typical HR of 75 beats/min and an SV of 70 ml/beat.

    Factors Influencing Heart Rate

    • The autonomic nervous system and various chemicals influence heart rate.
    • Sympathetic activation during stress releases norepinephrine, increasing HR by faster pacemaker firing and enhanced contractility.
    • Parasympathetic activation via acetylcholine results in hyperpolarization of pacemaker cells, slowing HR.

    Chemical Regulation of Heart Rate

    • Hormonal factors such as epinephrine from the adrenal medulla raise HR and contractility; thyroxine also boosts HR.
    • Appropriate ionic concentrations (Ca2+, K+) are essential for cardiac function; imbalances can be detrimental.

    Blood Pressure Regulation

    • Blood pressure is regulated by cardiac output, peripheral resistance, and blood volume.
    • Mean arterial pressure (MAP) is defined as MAP = CO × total peripheral resistance (TPR).
    • Changes in SV, HR, or TPR directly impact MAP, with vessel diameter playing a significant role in peripheral resistance.

    Measurement of Blood Pressure

    • Systemic arterial blood pressure is measured indirectly using a sphygmomanometer to determine systolic and diastolic pressures.
    • Normal systolic pressure is less than 120 mm Hg; normal diastolic pressure is less than 80 mm Hg.

    Baroreceptor Reflexes

    • Located in carotid sinuses and aortic arch; they detect changes in MAP.
    • High MAP stimulates baroreceptors to decrease cardiac output and induce peripheral vasodilation, lowering blood pressure.
    • Conversely, low blood pressure prompts an increase in cardiac output and peripheral vasoconstriction.

    Regulatory Mechanisms

    • Neural regulation involves the cardiovascular center in the medulla, which houses cardiac and vasomotor centers.
    • Cardioacceleratory center boosts cardiac output; cardioinhibitory center reduces it.
    • Vasomotor center controls vasoconstriction and vasodilation via adrenergic and cholinergic nerves, respectively.

    Long-term Regulation of Blood Pressure

    • Long-term blood pressure adjustments are mediated through renal control mechanisms.
    • Short-term regulation includes neural mechanisms and hormonal responses for immediate blood pressure stabilization.

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    Description

    Explore the role of the vagus nerve in the parasympathetic nervous system. This quiz covers the anatomy, functions, and effects on heart rate regulation, particularly focusing on the dorsal motor nucleus and cardoinhibitory center.

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