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?

α and β2 (D) Signup and view all the answers

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

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) Signup and view all the answers

Which of these actions are caused by β1 receptors?

Increased heart rate (A) Signup and view all the answers

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

β1 (D) Signup and view all the answers

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

α receptor (D) Signup and view all the answers

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

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

Where are the cell bodies of parasympathetic preganglionic neurons located?

Brainstem and sacral cord (B) Signup and view all the answers

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

Acetylcholine (ACh) (A) Signup and view all the answers

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

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

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

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

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

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

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

Stimulation of digestion and relaxation of the bladder (B) Signup and view all the answers

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

Acetylcholine (ACh) (A) Signup and view all the answers

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

Sympathetic preganglionic neurons release norepinephrine. (A) Signup and view all the answers

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

Prepares the body for "fight or flight" responses (C) 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?

Regulation of blood pressure (C) Signup and view all the answers

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

To maintain blood pressure during postural changes (B) 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?

Hypoglycemia (D) 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?

It highlights the fact that the sympathetic nervous system below the lesion is less responsive. (D) 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?

Stimulation of digestion (A) 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?

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

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

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

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

A sudden drop in blood pressure (B) Signup and view all the answers

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

Increases heart rate (A) Signup and view all the answers

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

α1 (D) Signup and view all the answers

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

Relaxes via β2 receptors (B) Signup and view all the answers

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

Contracts via M receptors (B) Signup and view all the answers

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

Mydriasis (dilation) (A) Signup and view all the answers

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

Catabolic responses (C) Signup and view all the answers

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

Ejaculation via α receptors (D) Signup and view all the answers

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

Contracts the sphincters via M receptors (C) Signup and view all the answers

What is the function of the autonomic nervous system?

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

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

Somatic (D) Signup and view all the answers

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

Acetylcholine (B) Signup and view all the answers

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

The sympathetic division is responsible for "fight or flight" responses, while the parasympathetic division is responsible for "rest and digest" responses. (B) Signup and view all the answers

What is the role of the enteric nervous system?

Control of digestion and other gastrointestinal functions (A) Signup and view all the answers

What is the effect of parasympathetic stimulation on the pupil?

Contraction of the pupil (B) Signup and view all the answers

Which pathway is involved in sympathetic innervation of the eye?

The carotid artery pathway (A) Signup and view all the answers

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

Horner's syndrome (B) Signup and view all the answers

Which component is not involved in the baroreceptor reflex?

Brachial plexus (C) Signup and view all the answers

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

Inhibition of sympathetic nervous system (C) Signup and view all the answers

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

Loss of reticulospinal control (D) Signup and view all the answers

What happens to the eyelid due to sympathetic pathway lesion?

Slight drooping (ptosis) occurs (D) Signup and view all the answers

Which cranial nerve is primarily involved in pupillary constriction?

CN III (D) Signup and view all the answers

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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Description

Test your knowledge of the autonomic nervous system with this quiz. Explore the functions and effects of both the sympathetic and parasympathetic branches, including their receptors and actions on various tissues. Perfect for students in physiology or related health fields.