Physiology: Autonomic Nervous System Quiz

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Questions and Answers

Which of these receptors is innervated by the sympathetic nervous system?

  • muscarinic
  • β2 (correct)
  • α (correct)
  • β1 (correct)

Which of these target tissues are innervated by the parasympathetic nervous system?

  • Heart (correct)
  • Bronchiole smooth muscle (correct)
  • Sweat gland
  • Skin and gut

Which of these actions are a direct result of the parasympathetic nervous system?

  • contraction of the gastrointestinal tract (correct)
  • sweating
  • dilatation of the pupil
  • contraction of the bladder wall (correct)
  • relaxation of the airway
  • relaxation of the vascular smooth muscle

Which of these receptors are involved in the relaxation of skeletal and coronary smooth muscle?

<p>α and β2 (D)</p> Signup and view all the answers

Which of these actions is caused by the sympathetic nervous system?

<p>Contraction of the sphincters (A), Constriction of the pupil (B), Relaxation of the smooth muscle wall of the bladder (D), Contraction of uterine muscle (E)</p> Signup and view all the answers

Which of these actions are caused by β1 receptors?

<p>Increased heart rate (A)</p> Signup and view all the answers

Which of these receptors are NOT involved in the stimulation of the digestive system?

<p>β1 (D)</p> Signup and view all the answers

Which of the following is responsible for the dilation of the pupil?

<p>α receptor (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic shared by both the parasympathetic and sympathetic nervous systems?

<p>Both systems use the neurotransmitter norepinephrine in their postganglionic neurons. (A)</p> Signup and view all the answers

Where are the cell bodies of parasympathetic preganglionic neurons located?

<p>Brainstem and sacral cord (B)</p> Signup and view all the answers

What neurotransmitter is released by preganglionic neurons of both the sympathetic and parasympathetic nervous systems?

<p>Acetylcholine (ACh) (A)</p> Signup and view all the answers

Which of the following cranial nerves are involved in the parasympathetic nervous system?

<p>CN III (Oculomotor), CN VII (Facial), CN IX (Glossopharyngeal) and CN X (Vagus) (A)</p> Signup and view all the answers

Which of the following statements is TRUE regarding sympathetic postganglionic neurons?

<p>They release norepinephrine (NE) at the synapse. (C)</p> Signup and view all the answers

What does the term "thoracolumbar" refer to in the context of the sympathetic nervous system?

<p>The location of the preganglionic cell bodies. (B)</p> Signup and view all the answers

Which of the following is a primary function of the parasympathetic nervous system?

<p>Stimulation of digestion and relaxation of the bladder (B)</p> Signup and view all the answers

What neurotransmitter is associated with the "rest and digest" response?

<p>Acetylcholine (ACh) (A)</p> Signup and view all the answers

Which of the following statements is NOT correct regarding the organization of the autonomic nervous system?

<p>Sympathetic preganglionic neurons release norepinephrine. (A)</p> Signup and view all the answers

Which of the following is a characteristic of the sympathetic nervous system?

<p>Prepares the body for &quot;fight or flight&quot; responses (C)</p> Signup and view all the answers

Which of these autonomic nervous system functions is MOST likely to be impaired after a lesion at the level of L1?

<p>Regulation of blood pressure (C)</p> Signup and view all the answers

What is the primary role of the baroreceptor reflex in relation to blood pressure fluctuations?

<p>To maintain blood pressure during postural changes (B)</p> Signup and view all the answers

Which of these conditions can lead to syncope (fainting) by disrupting the proper functioning of the autonomic nervous system?

<p>Hypoglycemia (D)</p> Signup and view all the answers

What is the significance of the statement "there is a lesser likelihood of autonomic dysreflexia, and if it occurs, it is less severe" in regard to a lesion at the level of L1?

<p>It highlights the fact that the sympathetic nervous system below the lesion is less responsive. (D)</p> Signup and view all the answers

Which of these responses is NOT typically associated with a low blood pressure response triggered by the sympathetic system?

<p>Stimulation of digestion (A)</p> Signup and view all the answers

Afferent signals from the baroreceptors in the carotid and aortic arch are directly involved in which of these processes?

<p>The regulation of blood pressure during postural changes (C)</p> Signup and view all the answers

How does the brain respond to decreased blood pressure signals from the baroreceptors?

<p>It decreases parasympathetic activity to raise blood pressure (C)</p> Signup and view all the answers

Which of these events is NOT a typical trigger for autonomic dysreflexia?

<p>A sudden drop in blood pressure (B)</p> Signup and view all the answers

What is the primary action of the sympathetic nervous system on the heart's SA node?

<p>Increases heart rate (A)</p> Signup and view all the answers

Which receptor type mediates the contraction of vascular smooth muscle in the skin and gut?

<p>α1 (D)</p> Signup and view all the answers

How does the sympathetic nervous system affect the gastrointestinal smooth muscle walls?

<p>Relaxes via β2 receptors (B)</p> Signup and view all the answers

What is the effect of the parasympathetic nervous system on the bladder wall?

<p>Contracts via M receptors (B)</p> Signup and view all the answers

Which action is associated with the sympathetic nervous system regarding the pupil?

<p>Mydriasis (dilation) (A)</p> Signup and view all the answers

What type of responses does the sympathetic nervous system typically evoke?

<p>Catabolic responses (C)</p> Signup and view all the answers

In terms of receptor action, how do the male sex organs respond to sympathetic stimulation?

<p>Ejaculation via α receptors (D)</p> Signup and view all the answers

What effect does the parasympathetic nervous system induce on the GI tract sphincters?

<p>Contracts the sphincters via M receptors (C)</p> Signup and view all the answers

What is the function of the autonomic nervous system?

<p>Regulates involuntary functions such as heart rate, digestion, and breathing (C)</p> Signup and view all the answers

Which of the following is NOT a division of the autonomic nervous system?

<p>Somatic (D)</p> Signup and view all the answers

What is the primary neurotransmitter released by the motor efferent at the neuromuscular junction?

<p>Acetylcholine (B)</p> Signup and view all the answers

Which of the following is a key difference between the sympathetic and parasympathetic divisions of the ANS?

<p>The sympathetic division is responsible for &quot;fight or flight&quot; responses, while the parasympathetic division is responsible for &quot;rest and digest&quot; responses. (B)</p> Signup and view all the answers

What is the role of the enteric nervous system?

<p>Control of digestion and other gastrointestinal functions (A)</p> Signup and view all the answers

What is the effect of parasympathetic stimulation on the pupil?

<p>Contraction of the pupil (B)</p> Signup and view all the answers

Which pathway is involved in sympathetic innervation of the eye?

<p>The carotid artery pathway (A)</p> Signup and view all the answers

What condition results from a lesion in the sympathetic pathway of the eye?

<p>Horner's syndrome (B)</p> Signup and view all the answers

Which component is not involved in the baroreceptor reflex?

<p>Brachial plexus (C)</p> Signup and view all the answers

What results from high blood pressure in the context of the baroreceptor reflex?

<p>Inhibition of sympathetic nervous system (C)</p> Signup and view all the answers

What triggers autonomic dysreflexia in individuals with high spinal cord lesions?

<p>Loss of reticulospinal control (D)</p> Signup and view all the answers

What happens to the eyelid due to sympathetic pathway lesion?

<p>Slight drooping (ptosis) occurs (D)</p> Signup and view all the answers

Which cranial nerve is primarily involved in pupillary constriction?

<p>CN III (D)</p> Signup and view all the answers

Flashcards

Autonomic Nervous System (ANS)

Controls the body's involuntary functions like heart rate, digestion, and breathing.

Sympathetic vs. Parasympathetic

The ANS is divided into two branches: the sympathetic and parasympathetic nervous systems.

Sympathetic Nervous System

The sympathetic system is responsible for the 'fight-or-flight' response, which prepares your body for action.

Parasympathetic Nervous System

The parasympathetic system is responsible for the 'rest-and-digest' response, which promotes relaxation and energy conservation.

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ANS Neurotransmitters

The ANS uses specific neurotransmitters to communicate between nerves and target tissues.

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β1 Receptor

A type of adrenergic receptor that, when activated, increases heart rate and contractility.

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β2 Receptor

A type of adrenergic receptor that, when activated, relaxes smooth muscle in the bronchioles, blood vessels of skeletal muscle, and the GI tract.

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Nicotinic Receptor

A type of cholinergic receptor found on postganglionic neurons of the ANS, as well as on skeletal muscle.

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Muscarinic Receptor

A type of cholinergic receptor found on target tissues innervated by the parasympathetic nervous system.

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Acetylcholine (ACh)

The neurotransmitter released by preganglionic neurons of both the sympathetic and parasympathetic nervous systems.

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Norepinephrine (NE)

The neurotransmitter released by postganglionic neurons of the sympathetic nervous system.

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Adrenal Medulla

The part of the sympathetic nervous system that releases NE directly into the bloodstream.

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Acetylcholine (ACh)

The primary neurotransmitter responsible for sweating.

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Two-Neuron Chain

Both the sympathetic and parasympathetic nervous systems exert their effects via a two-neuron chain, with a peripheral synapse typically located within a ganglia.

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Preganglionic Neuron

The first neuron in the chain is called the preganglionic neuron, and it releases acetylcholine (ACh).

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Acetylcholine (ACh) Release

The preganglionic neuron of both the sympathetic and parasympathetic systems releases acetylcholine (ACh).

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Postganglionic Neuron

The second neuron in the chain is called the postganglionic neuron. It releases different neurotransmitters depending on the system..

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Parasympathetic Postganglionic Neurotransmitter

The postganglionic neurons of the parasympathetic nervous system release acetylcholine (ACh).

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Sympathetic Postganglionic Neurotransmitter

The postganglionic neurons of the sympathetic nervous system release norepinephrine (NE).

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Preganglionic Cell Body Location [Difference]

The location of the preganglionic cell body is different for the sympathetic and parasympathetic nervous systems.

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How does the sympathetic nervous system affect the SA node?

The Sinoatrial (SA) node is the pacemaker of the heart, responsible for initiating heartbeat. Stimulation by the sympathetic nervous system via β1 receptors increases heart rate.

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How does the sympathetic nervous system impact heart contractility?

The sympathetic nervous system increases heart muscle contractility via β1 receptors. This makes the heart pump harder.

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What is the sympathetic effect on skin and gut blood vessels?

The sympathetic nervous system causes vasoconstriction in skin and gut blood vessels via α receptors, diverting blood to vital organs. This helps with 'fight-or-flight.'

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How does the sympathetic nervous system affect skeletal and coronary blood vessels?

The sympathetic nervous system can cause either relaxation or contraction in skeletal and coronary blood vessels depending on the receptor type (β2 or α).

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How does the sympathetic nervous system affect gastrointestinal smooth muscle?

The sympathetic nervous system relaxes gastrointestinal smooth muscle via β2 receptors, decreasing motility and digestion. Think 'fight-or-flight' and prioritization of energy.

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How does the sympathetic nervous system affect gastrointestinal sphincters?

The sympathetic nervous system contracts gastrointestinal sphincters via α receptors. This helps control the flow of food and waste during 'fight-or-flight.'

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How does the sympathetic nervous system affect the bladder?

The sympathetic nervous system relaxes the bladder muscle wall via β2 receptors, delaying urination. Think 'fight-or-flight' and prioritizing immediate needs.

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How does the sympathetic nervous system affect the bladder neck?

The sympathetic nervous system contracts the bladder neck (sphincter) via α receptors, preventing urination. Think 'fight-or-flight' and controlling body functions.

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Lesion in the Sympathetic Nervous System

A disruption in the sympathetic nervous system below the point of the lesion, affecting blood vessel regulation and reducing the risk of autonomic dysreflexia.

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Autonomic Dysreflexia

A medical condition characterized by an exaggerated response of the autonomic nervous system, often caused by a trigger below the level of a spinal cord injury.

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Baroreceptor Reflex

A reflex that helps regulate blood pressure and maintain blood flow to the brain, involving the baroreceptors in the carotid arteries and aortic arch.

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Presyncope

The feeling of lightheadedness or dizziness that can precede fainting.

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Syncope (Fainting)

A brief loss of consciousness caused by insufficient blood flow to the brain.

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Hypovolemia

A condition caused by a decrease in blood volume.

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Cardiovascular Failure

A condition where the cardiovascular system fails to maintain adequate blood pressure and blood flow.

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Autonomic Nervous System Failure

A condition where the autonomic nervous system fails to regulate blood flow to the brain.

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Miosis

Pupil constriction caused by the parasympathetic nervous system. It occurs via the Sphincter pupillae muscle.

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Mydriasis

Pupil dilation caused by the sympathetic nervous system. It occurs via the Dilator iridis muscle.

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Horner's Syndrome

A group of symptoms caused by interruption of the sympathetic nerve pathway, leading to a drooping eyelid (ptosis), constricted pupil (miosis), and a bloodshot appearance in the eye.

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Baroreceptors

Sensory receptors in the carotid artery and aortic arch that detect changes in blood pressure.

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Sympathetic Response to High Blood Pressure

The sympathetic nervous system's response to a sudden increase in blood pressure. It causes a decrease in heart rate and vasodilation, reducing blood pressure.

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Sympathetic Response to Low Blood Pressure

The sympathetic nervous system's response to a sudden decrease in blood pressure. It causes an increase in heart rate and vasoconstriction, increasing blood pressure.

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Study Notes

Autonomic Nervous System (ANS)

  • The ANS controls many bodily functions, often involuntarily.
  • It regulates various organ systems.
  • It maintains homeostasis (balance).
  • It consists of afferent (sensory) and efferent (motor) components.

Homeostasis

  • Homeostasis is the balance within the body.
  • This involves maintaining equilibrium regarding bodily functions and chemical fluid composition.
  • Negative feedback loops are crucial to homeostasis involving sensors, a control center, and effectors.

Negative Feedback Loop

  • A control circuit that maintains balance.
  • If a variable (e.g., temperature) increases from the set point, the loop activates effectors to decrease it.
  • Conversely, if the variable decreases from the set point, the loop activates effectors to increase it
  • Includes sensors, a control center, and effectors.
  • Example: Body temperature regulation.

ANS Organization

  • Three divisions: sympathetic, parasympathetic, enteric.
  • Sympathetic: "fight or flight" response, often increasing energy output.
  • Parasympathetic: "rest and digest" response, often promoting energy conservation.
  • Enteric: Intrinsic nervous system within the GI tract.

Synapses, Neurotransmitters and Receptors

  • Neurotransmitters: Chemical messengers.
  • Receptors: Specific protein sites for these messengers.
  • Many different neurotransmitters and their corresponding receptors are involved in ANS function.
  • Key neurotransmitters include Acetylcholine (ACh) and Norepinephrine.

Sympathetic Division

  • Preganglionic neurons are in the spinal cord (thoracolumbar).
  • Postganglionic neurons typically use norepinephrine (NE) at target tissues.
  • Actions: increased heart rate, pupil dilation, blood pressure increases.

Parasympathetic Division

  • Preganglionic neurons are in the brainstem and sacral regions of the spinal cord.
  • Postganglionic neurons typically use acetylcholine (ACh) at target tissues.
  • Actions: decreased heart rate, pupil constriction, blood pressure reduced.

ANS Control of Target Tissues

  • Effects on specific organs/tissues vary depending on the division activated.
  • Examples: Heart rate, blood flow, digestion, pupils.
  • Specific tissues can react differently to similar neurotransmitters, depending on the receptor(s) present

ANS Control of Eyes

  • Parasympathetic innervation constricts the pupils (miosis).
  • Sympathetic innervation dilates the pupils (mydriasis).

ANS Control of Body Temperature

  • Sympathetic: regulates blood flow to skin, sweating, and shivering.
  • Parasympathetic: has little influence.

ANS Control of Bladder

  • Parasympathetic: contraction of the bladder.
  • Sympathetic: Relaxation of the bladder.
  • Both work with the somatic system for continence.

Autonomic Dysreflexia

  • A condition in individuals with spinal cord injury.
  • Severe hypertension often accompanied by bradycardia.
  • Associated with uncontrolled/unregulated sympathetic activity.
  • Often results from noxious stimuli below the injury level.
  • Requires immediate intervention.

Syncope

  • Loss of consciousness, often related to insufficient blood flow to the brain.
  • Possible causes include: orthostatic hypotension, hypovolemia, or cardiac issues.

Congenital Megacolon

  • Hirschsprung's disease is a disorder of the enteric nervous system
  • Failure of ganglion cells migration in the colon
  • Distension/constipation in the colon.
  • Usually diagnosed in newborns and requires surgery.
  • Problems with gut motility.

Compromised Bladder Control

  • Damage to the sacral spinal cord, etc., can disrupt bladder function.
  • Incontinence (loss of bladder control) can result.
  • Bladder and sphincter dyssynergia is a possible manifestation from spinal cord issues.

Learning Objectives:

  • Define homeostasis and negative feedback loops.
  • Describe the organization of sympathetic and parasympathetic divisions.
  • Identify neurotransmitters and receptors involved in ANS.
  • Review ANS effects on various organs, particularly pupils, heart, blood vessels, bladder.

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MPAS; PAEP7002 Autonomic Nervous System PDF

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