Autonomic Nervous System (ANS) Anatomy

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Questions and Answers

What type of antagonism is exhibited by the dual innervation of organs by the ANS?

Physiological

Pharmacological

Dynamic (correct)

Static

Which of the following organs receives innervation only from the sympathetic system?

Skeletal muscle

Kidney (correct)

Pituitary gland

Heart

What is a key difference between the efferent somatic nervous system and the ANS?

Type of neurotransmitters released

Voluntary vs. involuntary control (correct)

Number of neurons involved

Somatic vs. visceral innervation

Which division of the ANS has a more limited distribution in the body?

Parasympathetic Signup and view all the answers

What is a characteristic of the parasympathetic division of the ANS?

One-to-one interactions Signup and view all the answers

Which of the following is NOT a characteristic of the sympathetic nervous system?

One-to-one interactions Signup and view all the answers

What is the main difference in the anatomical arrangement of neurons between the somatic and ANS divisions?

Presence or absence of ganglia Signup and view all the answers

Which of the following statements is TRUE about the vagus nerve?

It slows down heart rate Signup and view all the answers

What is the main function of the parasympathetic nervous system?

To maintain homeostasis within the body Signup and view all the answers

What is the relationship between the parasympathetic and sympathetic nervous systems?

The parasympathetic system usually acts to oppose or balance the actions of the sympathetic system Signup and view all the answers

What would happen if the parasympathetic system were to discharge as a complete system?

The body would experience massive, undesirable, and unpleasant symptoms Signup and view all the answers

What type of impulses travel to integrating centers in the CNS?

Afferent impulses Signup and view all the answers

What is the function of the hypothalamus in the control of autonomic functions?

To integrate sensory information from the viscera and other autonomically innervated structures Signup and view all the answers

What is the role of the CNS in the control of autonomic functions?

To integrate sensory information from the viscera and other autonomically innervated structures Signup and view all the answers

What type of stimuli elicit sympathetic and parasympathetic actions?

Different stimuli Signup and view all the answers

What is the purpose of the ANS?

To control autonomic functions Signup and view all the answers

What is the primary function of the preganglionic neuron in the autonomic nervous system?

To make synaptic connections in ganglia with postganglionic neurons Signup and view all the answers

What is the term for the aggregation of nerve cell bodies located in the peripheral nervous system?

Ganglia Signup and view all the answers

Which of the following is NOT a type of neuron in the autonomic nervous system?

Sensory neurons Signup and view all the answers

What is the term for the nervous system that controls digestion, cardiac output, blood flow, and glandular secretions?

Autonomic nervous system Signup and view all the answers

Which of the following is a function of the afferent neurons in the autonomic nervous system?

Sensing pressure in the carotid sinus and aortic arch Signup and view all the answers

What is the term for the nervous system that is responsible for the 'fight or flight' response?

Sympathetic nervous system Signup and view all the answers

Where is the cell body of the postganglionic neuron located?

In the ganglia Signup and view all the answers

What is the term for the nervous system that is responsible for regulating the involuntary functions of the viscera?

Autonomic nervous system Signup and view all the answers

What is the primary function of second messenger molecules in a cellular response?

To intervene between the original message and the ultimate effect on the cell Signup and view all the answers

Which of the following receptors are coupled to the second messenger system?

Muscarinic receptors Signup and view all the answers

What is the name of the system that involves adenylyl cyclase as a second messenger?

Adenylyl cyclase system Signup and view all the answers

What type of receptors do not directly open ion channels?

Muscarinic receptors Signup and view all the answers

What is the term for the original message that binds to a neurotransmitter receptor?

First messenger Signup and view all the answers

What is the role of a G protein in the second messenger system?

To activate the second messenger cascade Signup and view all the answers

What is the term used to describe the collection of nerve fibers that innervate the gastrointestinal tract, pancreas, and gallbladder?

Brain of the gut Signup and view all the answers

Which of the following is NOT a function of the sympathetic nervous system?

Promoting digestion and absorption of nutrients Signup and view all the answers

What is the term used to describe the body's response to emergencies, such as trauma or fear?

Fight-or-flight response Signup and view all the answers

What is the main difference between the sympathetic and parasympathetic nervous systems?

The sympathetic nervous system is active during stress, while the parasympathetic nervous system is active during rest Signup and view all the answers

What is the function of the enteric nervous system in regulating the GI tract?

Controlling the motility, exocrine and endocrine secretions, and microcirculation of the GI tract Signup and view all the answers

What is the effect of sympathetic stimulation on the pupils?

Dilation of the pupils Signup and view all the answers

What is the function of the adrenal medulla during the 'fight-or-flight' response?

Releasing epinephrine and norepinephrine into the bloodstream Signup and view all the answers

What is the characteristic of the sympathetic nervous system that allows it to respond to stressful situations?

It adjusts in response to stressful situations Signup and view all the answers

Study Notes

Organization of the Autonomic Nervous System (ANS)

The ANS is also known as the visceral, vegetative, or involuntary nervous system due to its involuntary nature and functions.
It is composed of efferent neurons that innervate smooth muscle of the viscera, cardiac muscle, vasculature, and the exocrine glands, controlling digestion, cardiac output, blood flow, and glandular secretions.

Anatomy of the ANS

The ANS carries nerve impulses from the CNS to the effector organs through two types of efferent neurons: the preganglionic neurons and the postganglionic neurons.
The cell body of the preganglionic neuron is located within the CNS, emerges from the brainstem or spinal cord, and makes a synaptic connection in ganglia.
The ganglia function as relay stations between the preganglionic neuron and the postganglionic neuron.
The cell body of the postganglionic neuron originates in the ganglion and terminates on effector organs, such as visceral smooth muscle, cardiac muscle, and the exocrine glands.

Efferent Neurons

The efferent ANS is divided into the sympathetic and the parasympathetic nervous systems, as well as the enteric nervous system.
The sympathetic and parasympathetic neurons originate in the CNS and emerge from two different spinal cord regions.

Functions of the Sympathetic Nervous System

The sympathetic nervous system is continually active to some degree, adjusting in response to stressful situations, such as trauma, fear, hypoglycemia, cold, and exercise.
The effect of sympathetic output is to increase heart rate and blood pressure, mobilize energy stores of the body, and increase blood flow to skeletal muscles and the heart while diverting flow from the skin and internal organs.
Sympathetic stimulation results in dilation of the pupils and the bronchioles, affecting GI motility and the function of the bladder and sexual organs.

Fight-or-Flight Response

The changes experienced by the body during emergencies are referred to as the “fight or flight” response.
These reactions are triggered both by direct sympathetic activation of the effector organs and by stimulation of the adrenal medulla to release epinephrine and lesser amounts of norepinephrine.

Functions of the Parasympathetic Nervous System

The parasympathetic division is involved in maintaining homeostasis within the body, required for life, and maintains essential bodily functions, such as digestion and elimination of wastes.
The parasympathetic division usually acts to oppose or balance the actions of the sympathetic division and generally predominates in “rest-and-digest” situations.

Role of the CNS in the Control of Autonomic Functions

The ANS requires sensory input from peripheral structures to provide information on the current state of the body.
Feedback is provided by streams of afferent impulses originating in the viscera and other autonomically innervated structures that travel to integrating centers in the CNS, such as the hypothalamus, medulla oblongata, and spinal cord.

Innervation by the ANS

Most organs in the body are innervated by both divisions of the ANS.
Dual innervation allows for antagonism, fine-tuning of homeostatic organ functions, and dynamic regulation.
Some effector organs, such as the adrenal medulla, kidney, pilomotor muscles, and sweat glands, receive innervation only from the sympathetic system.

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Description

Learn about the organization and functions of the Autonomic Nervous System (ANS), including its control over digestion, cardiac output, and more.