Autonomic Nervous System Overview

Questions and Answers

What is the primary effect of beta-adrenergic blockers on the heart?

Enhance bronchodilation and peripheral resistance

Reduce heart rate and decrease conduction velocity (correct)

Increase heart rate and force of contraction

Increase vasodilation and lipolysis

Which medication is considered a non-selective beta blocker?

Metoprolol

Propranolol (correct)

Atenolol

Diltiazem

What is the mechanism through which norepinephrine affects cardiac muscle activity?

Increases perfusion to cardiac tissue

Inhibits Na+ and Ca+2 channel influx

Increases cAMP and activates PKA (correct)

Reduces conduction velocity through the AV node

Which of the following medications is a calcium channel antagonist?

Verapamil Signup and view all the answers

What effect do beta-2 adrenergic receptors have on smooth muscle?

Inhibit Myosin Light Chain Kinase Signup and view all the answers

In the context of cardiac regulation, what is the role of sympathomimetic agents like epinephrine?

Increase heart rate and lipolysis Signup and view all the answers

Which condition might benefit from the use of a beta-1 selective blocker like Metoprolol?

Heart failure with tachycardia Signup and view all the answers

What symptom is most likely associated with a heart rate of 176 bpm and the patient's description of feeling light-headed?

Arrhythmia Signup and view all the answers

What is the most likely underlying cause of the patient's increased heart activity in this scenario?

Coronary artery disease Signup and view all the answers

How does atrial fibrillation contribute to a decrease in blood pressure?

Through inefficient heart contractions Signup and view all the answers

Which of the following is NOT a recognized cause of atrial fibrillation?

Regular exercise Signup and view all the answers

What effect does a heart rate of 176 bpm have on the heart's pumping efficiency?

It reduces the time for the heart to fill with blood Signup and view all the answers

Which autonomic receptor type is primarily involved in regulating heart rate?

Beta-1 receptors Signup and view all the answers

What might be a common physical stressor that could lead to atrial fibrillation?

Surgery Signup and view all the answers

How does caffeine consumption potentially lead to heart rhythm abnormalities?

By acting as a stimulant that increases heart rate Signup and view all the answers

Which of the following scenarios might lead to problems with the heart's natural pacemaker?

Electrolyte imbalance Signup and view all the answers

Which part of the autonomic nervous system is responsible for the 'fight or flight' response?

Sympathetic division Signup and view all the answers

What is a defining characteristic of preganglionic fibers in the sympathetic division compared to those in the parasympathetic division?

They originate from the thoracic and lumbar regions. Signup and view all the answers

Which cells in the peripheral nervous system develop from neural crest cells?

Post-ganglionic sympathetic and parasympathetic nerves Signup and view all the answers

In which area of the body do parasympathetic fibers predominantly emerge from?

Sacral region Signup and view all the answers

What is the anatomical difference in the lengths of postganglionic fibers between the sympathetic and parasympathetic divisions?

Postganglionic fibers are longer in the sympathetic division. Signup and view all the answers

Which structure is associated with the adrenal medulla in terms of the autonomic nervous system?

Chromaffin cells Signup and view all the answers

What type of fibers synapse onto postganglionic fibers in the sympathetic nervous system?

Long preganglionic fibers Signup and view all the answers

What clinical symptoms might indicate an overactive sympathetic nervous system?

Rapid heart rate and light-headedness Signup and view all the answers

Which of the following accurately describes the relationship between the sympathetic chain ganglia and the sympathetic division?

They are part of the pathway for postganglionic sympathetic fibers. Signup and view all the answers

What is the primary function of the parasympathetic division of the autonomic nervous system?

To conserve energy and promote maintenance activities Signup and view all the answers

What is a common side effect that a patient should be monitored for when taking beta blockers?

Feeling dizzy or tired Signup and view all the answers

Which beta blocker is considered non-selective?

Propranolol Signup and view all the answers

What type of receptor mediates the constriction of the pupil in response to low light conditions?

Muscarinic M3 Signup and view all the answers

What effect does acetylcholine have on cardiac activity via M2 muscarinic receptors?

Decreases cAMP and PKA levels Signup and view all the answers

Which medication would be appropriate to induce pupil dilation during an eye exam?

Alpha 1 agonist Signup and view all the answers

What is one potential consequence of a patient taking an overdose of both a beta blocker and a calcium channel antagonist?

Comatose state and cold skin Signup and view all the answers

To increase fluid secretion on the cornea of the eye, which autonomic nervous system division needs to be activated?

Parasympathetic Signup and view all the answers

Which calcium channel antagonist is known for its ability to also lower heart rate?

Diltiazem Signup and view all the answers

What neurotransmitter is involved in the response to activate the muscarinic receptors that decrease heart rate?

Acetylcholine Signup and view all the answers

In patients taking beta blockers, what is a likely cardiovascular effect?

Decreased force of contraction Signup and view all the answers

Which type of receptor is mainly responsible for increasing intracellular calcium in response to stimulation?

Alpha 1 Signup and view all the answers

When a patient experiences cold hands or feet while on medication, which class of drugs might be responsible?

Calcium channel antagonists Signup and view all the answers

What is the primary action of calcium channel antagonists in relation to cardiac function?

Decrease contractility and heart rate Signup and view all the answers

What physiological effect is primarily mediated by the activation of Beta 1 receptors?

Increased heart rate Signup and view all the answers

In response to a poorly lit room, which muscle type is activated for pupil constriction?

Sphincter muscle Signup and view all the answers

Which receptor types decrease cyclic AMP (cAMP) levels when activated?

Alpha 2 and M2 Signup and view all the answers

Study Notes

Autonomic Nervous System (ANS) Overview

ANS regulates involuntary actions within the body.
Two main divisions:
- Sympathetic ("fight or flight")
- Parasympathetic ("rest and digest").

Development of the ANS

Originates from Neural Crest Cells.
Structures derived include:
- Smooth muscle
- Schwann and Satellite cells
- Post-ganglionic sympathetic and parasympathetic nerves
- Enteric nerves
- Chromaffin cells in the adrenal medulla.

Heart Rate Regulation

Increased heart activity leads to symptoms such as tachycardia (176 bpm), light-headedness, and shortness of breath.
Atrial fibrillation is often identified as a cause of increased heart rate.
Common causes of atrial fibrillation include:
- Coronary artery disease
- Congenital heart defects
- Heart valve abnormalities
- High blood pressure
- Lung diseases
- Problems with natural pacemakers
- Physical stressors
- Use of stimulants (e.g., caffeine, tobacco).

Anatomical Differences in ANS

Sympathetic nervous system fibers are short preganglionic and long postganglionic, originating from thoracic and lumbar regions.
Parasympathetic fibers are long preganglionic and short postganglionic, originating from the brainstem and sacral regions.

Pharmacological Management

Possible medications for increased heart rate and blood pressure management include:
- Beta-adrenergic blockers (e.g., Propranolol, Metoprolol, Atenolol).
- Calcium channel antagonists (e.g., Diltiazem, Verapamil).
Medication side effects may include dizziness, fatigue, constipation, and low blood pressure.

Sympathetic Cardiac Regulation

Norepinephrine and epinephrine act on Beta1 adrenergic receptors, increasing cAMP levels, leading to heightened cardiac activity.
Beta2 receptors induce smooth muscle relaxation, resulting in vasodilation through cAMP modulation.

Parasympathetic Cardiac Regulation

Acetylcholine acts on M2 muscarinic receptors, resulting in decreased cAMP, reducing cardiac activity via K+ efflux.

Emergency Management for Overdose

In cases of medication overdose (e.g., beta blockers, calcium channel antagonists), immediate interventions are required for low blood pressure and heart rate.

Receptor Types and Signaling

Sympathetic receptors:
- Beta1 (Gs) - increases cAMP and cardiac output.
- Alpha1 (Gq) - induces smooth muscle contraction.
- Alpha2 (Gi) - decreases cAMP.
Parasympathetic receptors:
- M2 (Gi) - reduces cardiac activity.
- M3 (Gq) - increases calcium and muscle contraction.

Eye Response Example

Pupil constriction in dim light exemplifies parasympathetic activity through muscarinic M3 receptors activated by acetylcholine.
Sympathetic agonists or muscarinic antagonists can induce pupil dilation for eye exams.
To increase corneal fluid, activation of the parasympathetic system through M3 receptors is required.

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Description

This quiz covers the fundamentals of the Autonomic Nervous System (ANS), including its divisions, development, and role in heart rate regulation. You'll explore the differences between the sympathetic and parasympathetic systems, as well as the implications of conditions like atrial fibrillation. Test your knowledge on how the ANS manages involuntary actions in the body.