L17 Autonomic Control of the Heart

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What is the main function of the Autonomic Nervous System (ANS)?

To regulate conscious thought processes

To facilitate the fight-or-flight response

To manage subconscious and involuntary bodily functions (correct)

To control voluntary muscle movements

Which component of the ANS is dominant during exercise?

Parasympathetic Nervous System

Both systems are equally dominant

Neither system is dominant during exercise

Sympathetic Nervous System (correct)

What is the main function of the Cardiac Inhibitory Center (CIC) within the Autonomic Nervous System?

To regulate blood vessel diameter

To increase heart rate and contractility

To coordinate the cardiovascular response to stress

To decrease heart rate and contractility (correct)

How does the Sympathetic Nervous System affect the heart?

It increases heart rate and contractility Signup and view all the answers

What is the main function of the Vasodilator Center within the Autonomic Nervous System?

To increase blood flow to active muscles Signup and view all the answers

What is the main function of the Cardiac Acceleration Center (CAC) within the Autonomic Nervous System?

To increase heart rate and contractility Signup and view all the answers

What is the effect of strong vagal stimulation on the heart?

Causes the ventricle to beat continuously at a rate of 25-40 beats/min Signup and view all the answers

Where does the majority of the vagus nerve supply in the heart during rest?

S.A. Node Signup and view all the answers

Which part of the heart receives no vagal fibers?

Ventricles Signup and view all the answers

From where is the sympathetic nervous system derived that supplies all parts of the heart?

(T1-T5) Signup and view all the answers

What is the effect of sympathetic stimulation on cardiac properties?

Increases excitability, rhythmicity, conductivity, and contractility Signup and view all the answers

Which part of the heart is primarily supplied by the parasympathetic nervous system during rest?

S.A. Node Signup and view all the answers

What is the primary effect of the parasympathetic nervous system on ventricular contractility?

Has no direct effect on ventricular contractility Signup and view all the answers

What is the primary effect of the sympathetic nervous system on ventricular contractility?

Increases the opening of Ca2+ channels in the myocyte Signup and view all the answers

What is the primary effect of norepinephrine released from post-ganglionic sympathetic fibers on vascular tone?

Vasoconstriction through activation of α1 and α2 adrenergic receptors Signup and view all the answers

Which of the following mechanisms does the sympathetic nervous system use to alter the electrical transmission of the sinoatrial node?

Decreasing Ca2+ conductance Signup and view all the answers

Which of the following correctly describes the effects of the sympathetic and parasympathetic nervous systems on the heart?

SNS increases heart rate and contractility, PSNS decreases heart rate and contractility Signup and view all the answers

What is the overall effect of norepinephrine on vascular tone?

Vasoconstriction Signup and view all the answers

Which of the following is the effect of parasympathetic stimulation on the heart?

Decreases excitability, rhythmicity, conductivity, and contractility Signup and view all the answers

Which neurotransmitter is released by post-ganglionic sympathetic fibers to increase heart rate?

Norepinephrine Signup and view all the answers

How does parasympathetic stimulation affect the AV node conductivity?

Slows conduction through the AV node Signup and view all the answers

Which receptor type is targeted by sympathetic stimulation to increase heart rate?

β1 adrenergic receptors Signup and view all the answers

Which of the following is NOT an effect of parasympathetic stimulation on the heart?

Causes coronary vasodilation Signup and view all the answers

Which cranial nerve supplies the SA node with parasympathetic fibers?

Right vagus nerve Signup and view all the answers

Which of the following statements correctly describes the effects of the sympathetic nervous system (SNS) and parasympathetic nervous system (PSNS) on heart rate and contractility?

SNS: ↑ heart rate, ↑ contractility; PSNS: ↓ heart rate, ↓ contractility Signup and view all the answers

Which component of the autonomic nervous system is dominant during resting conditions?

Parasympathetic nervous system Signup and view all the answers

Which of the following mechanisms is responsible for the sympathetic nervous system's effect on heart rate and contractility?

Release of norepinephrine at the sinoatrial node and cardiac muscle Signup and view all the answers

Which of the following statements accurately describes the effect of the autonomic nervous system on blood vessels?

SNS: vasoconstriction; PSNS: vasodilation Signup and view all the answers

During exercise, which component of the autonomic nervous system becomes dominant?

Sympathetic nervous system Signup and view all the answers

Which of the following best describes the role of the autonomic nervous system?

Regulating involuntary bodily functions Signup and view all the answers