Step One: Embrace the Gift of Life

Ground yourself in this moment.  As you tune into your life – whatever may feel stable and whatever may feel overwhelming – acknowledge this fundamental truth: Your life is a precious gift.

Now reflect on these questions:

• Now reflect on these questions:
• How am I intentionally acknowledging and expressing what I am grateful for in my life?

Remember, how you respond to the gifts in your life is your choice. But the choice you make will shape your entire perspective and experience of whatever is before you.

Step Two: Remember the Good

Step Two: Remember the Good

First, think of a recent joy:

• What made this moment meaningful to you?
• How did this experience connect you to something larger than yourself?

Now recall a moment of difficulty in your life. Look deeper:

• Who or what supported you during that time?
• What goodness carried you through that challenge?
• What strength or wisdom did you discover within yourself?

As you remember these experiences, notice how meaning reveals itself not in the events themselves, but in your perspective and the good that you recognize within them.

Step Three: Discover Meaning in the Present

Finally, turn your attention to this very moment. Look around you with fresh eyes:

• What do you see, hear, or feel that you’re grateful for right now?
• Where do you sense an invitation to respond to life with purpose?

Remember, meaning isn’t something you need to chase or manufacture. It’s already here, waiting to be discovered. Your task is simply to notice and appreciate it.

Autonomic Nervous System

The autonomic nervous system is the division of the peripheral nervous system that is responsible for distributing signals from the central nervous system to all tissues except for skeletal muscle. Its control of cardiac muscle, smooth muscle, glands, and fat cells allows the autonomic nervous system to both maintain a favorable internal environment and, very importantly, adapt to change. The autonomic nervous system consists of three major divisions:

• Enteric nervous system
• Parasympathetic nervous system
• Sympathetic nervous system

This lesson will focus on the parasympathetic and sympathetic nervous systems.

Parasympathetic Nervous System

The parasympathetic nervous system is the division of the autonomic nervous system that predominates under resting conditions and is responsible for the control of day-to-day housekeeping functions, such as urination and digestion. Therefore, the parasympathetic nervous system is often referred to as the rest-and-digest division of the autonomic nervous system. A good scenario that you can think of in order to understand the functioning of the parasympathetic nervous system is you lying on the couch on a Sunday morning, binge-watching the latest series on Netflix and eating a huge bag of potato chips. In this scenario your body's biggest concern is to digest the mountain of potato chips that you are munching through. The importance of the parasympathetic nervous system therefore lies in its control of normal resting day-to-day housekeeping activities, which, of course, keep the body alive and healthy.

Sympathetic Nervous System

The sympathetic nervous system is the division of the autonomic nervous system that prepares the body for heightened activity and is associated with increased metabolic output. This division of the autonomic nervous system, when fully activated, produces the characteristic fight-or-flight reaction. This reaction, as its name suggests, prepares the necessary tissues of the body to stand and fight or run away for your life! A perfect scenario that can be used to understand the role of the sympathetic nervous system in the human body is this - you are walking down the road, minding your own business, when all of a sudden there is a loud hoot right next to you. We've all experienced something similar and know that in this situation your heart begins to race, your breathing increases and you begin to sweat. This is the fight-or-flight reaction in action! The importance of the sympathetic nervous system in the human body is therefore during emergency situations, where we need the body to react in a critical way in order to keep us alive.

Dual Innervation

Although there are some organs in the human body that receive innervation from just one of the divisions of the autonomic nervous system, most of the vital organs receive innervation from both the parasympathetic and sympathetic nervous systems. This is known as dual innervation. The effect of the parasympathetic and sympathetic nervous systems at these organs is often one of opposition, where the parasympathetic nervous system will, for example, decrease heart rate, while the sympathetic nervous system will increase it.

Autonomic Responses in the Human Body

The effects of the parasympathetic and sympathetic divisions of the autonomic nervous system on various organs within the human body are indicated in Table 1.

Organ	Parasympathetic Control	Sympathetic Control
Eyes	Constricts pupil	Dilates pupil
Salivary glands	Stimulates salivation	Inhibits salivation
Heart	Slows heart rate	Accelerates heart rate
Lungs	Constricts bronchi	Dilates bronchi
Stomach	Stimulates digestion	Inhibits digestion
Liver	Stimulates bile release	Stimulates glucose release
Intestines	Stimulates peristalsis and secretion	Inhibits peristalsis and secretion
Bladder	Contracts bladder	Relaxes bladder
Genitals	Erection	Ejaculation

Using the two scenarios described above, it is easy to understand the organ responses that are initiated by the parasympathetic and sympathetic nervous systems.

Parasympathetic Responses

If you are lying on the couch watching television and eating your potato chips, then your body is at rest and its main concern is digestion of your snack. Therefore, if we look at Table 1, we will see that our digestive organs (i.e. salivary glands, stomach, liver, and intestines) are stimulated by parasympathetic activation, while the parasympathetic nervous system keeps the other organs at rest (i.e. eyes, heart, lungs). Besides digestion, all other housekeeping activities, such as waste removal, will be stimulated to occur and therefore your bladder will contract, and urination will occur, to rid the body of waste.

Sympathetic Responses

During the vital 'fight-or-flight reaction,' your vital organs need to ensure that they are working hard enough to allow us to fight or flee for our lives. Therefore, as seen in Table 1, the vital organs (i.e. eyes, lungs, heart, and liver) will be stimulated to react in a way that they can meet the demands of increased bodily activity, while the non-vital organs (i.e. digestive organs and bladder) will be inhibited. This allows the body to focus on meeting the demands of the emergency situation and not wasting vital resources on housekeeping activities (such as digestion and urination).

Example – Autonomic Control of Genitalia

The reproductive system is an excellent example of the fact that the activities of the parasympathetic and sympathetic nervous systems do not always oppose each other in the human body, and, sometimes, they may very well work together towards a common goal. In this case the common goal is procreation. When in a resting state, the parasympathetic nervous system is responsible for erection of the reproductive organs. Once erection has occurred, the sympathetic nervous system takes over, in order to achieve ejaculation of the reproductive organs. This ejaculation is accompanied by other sympathetic responses in the body that accompany an orgasm, such as an increase in heart rate, pupil dilation, and increased breathing rate. It is important here to remember that ejaculation will not occur unless the resting parasympathetic state has caused erection. Therefore, it would be impossible for ejaculation to occur during the ‘fight-or-flight’ reaction.

Lesson Summary

The autonomic nervous system controls cardiac muscle, smooth muscle, glands, and fat cells, in order to both maintain a favorable internal environment and to allow the body to react to change. Two of the major divisions of the autonomic nervous system are the parasympathetic and sympathetic nervous systems.

The parasympathetic nervous system, or rest-and-digest division, is responsible for day-to-day housekeeping functions such as digestion and urination, and predominates under resting conditions. The sympathetic nervous system, when fully activated, is able to produce the characteristic fight-or-flight reaction that allows the body to respond to emergency situations. This reaction is associated with an increase in activity of the vital organs, such as the lungs, heart, skeletal muscles, brain and liver, and a decrease in activity of the organs associated with housekeeping activities, such as those associated with digestion and urination. In the human reproductive system, the parasympathetic and sympathetic nervous systems cooperate in order to achieve procreation. The parasympathetic nervous system controls erection and then hands over to the sympathetic nervous system, which achieves ejaculation. In this way, the two systems cooperate in order to achieve a common goal.

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Answer Key

Worksheet: Autonomic Nervous System: Parasympathetic & Sympathetic Nervous Activity

• The ___ nervous system is known as the 'rest-and-digest' division, since it is responsible for typical day-to-day housekeeping activities.

  • enteric
  • sympathetic
  • parasympathetic
  • autonomic

• Which of the following tissues are NOT controlled by the autonomic nervous system?

  • fat cells
  • skeletal muscle
  • cardiac muscle
  • smooth muscle

• During the male sexual response, the ___ nervous system is responsible for ejaculation.

  • parasympathetic
  • enteric
  • sympathetic
  • somatic

• Which of the divisions of the autonomic nervous system would you associate with the following scenario: it is a Saturday evening and you have decided to stay in bed in order to read the new novel that your friend recommended.

  • autonomic nervous system
  • enteric nervous system
  • parasympathetic nervous system
  • sympathetic nervous system

• During the 'fight-or-flight' reaction, heart rate will ___.

  • increase
  • not change
  • stay the same
  • decrease

Somatic Nervous System

The somatic nervous system (SNS) is part of the peripheral nervous system (PNS) that regulates voluntary body movements through skeletal muscle innervation. To allow for such innervation, two main components are essential:

• Afferent (sensory) nerves relay various senses throughout the body to the spinal cord and brain (central nervous system). For instance, thermoreceptors in the skin may convey the sensation of heat if one accidentally places their finger on a hot stove. This response will then be transmitted to the spinal cord and brain via afferent nerves.
• Efferent (motor) nerves relay a response from the brain and spinal cord to the body, which results in movement via muscle contractions. In the case of the finger being placed on the hot stove, reflex arc results with the motor portion initiating immediate withdrawal of the affected finger from the stove to minimize any further damage. Efferent nerves may also trigger more complicated movements via muscle contractions, such as walking, running, gymnastic moves, etc.

Other components of the SNS include:

• Spinal nerves: Spinal nerves are located in the PNS and represent the combination of dorsal nerve roots, which contain sensory information, and ventral nerve roots, which contain motor information. Thus, they are considered mixed nerves. Different spinal nerves will innervate different muscles and glands in the body.
• Cranial nerves: Cranial nerves originate from the brain, especially the brainstem, and they transmit information into and out of this brain region. They are generally numbered by a roman number (I through XII) and include an associated name, such as optic nerve or cochlear nerve. Cranial nerves will relay information regarding the senses especially, such as vision, hearing, smell, taste, but they can also regulate several muscles, such as eye muscles, those of the mouth, neck, shoulder, and tongue muscles.

Functions of the Somatic Nervous System (SNS)

The primary function of the SNS is to regulate voluntary movement that could be through conscious or unconscious mechanisms, i.e., a reflex arc.

Upper cell bodies of motor neurons within the precentral gyrus triggers the corticospinal tract. Axons from motor neurons in the ventral horn synapse on the skeletal muscle that results in the contraction of such muscles. This occurs due to motor neuron release of acetylcholine at the axon terminal/synapse region. This neurotransmitter binds and activates nicotinic acetylcholine receptors expressed by skeletal muscle, which results in muscle contraction and movement.

• A reflex arc is where there is almost a direct link between sensory and motor output, as a quick response may be required, such as withdrawal of one’s finger from a burning stove. Such reflexes may be simple or complex in terms of how much sensory information is conveyed and the neurons that will initiate a response.
• A monosynaptic reflex involves only a single synapse between sensory and motor response. The main example of this type of reflex is the knee jerk (patellar) reflex, where tapping the patellar tendon results in a kick of the knee. While withdrawing a hand from a hot stove is protective, the knee jerk reflex may be a remnant of a more primitive response, as no obvious protection comes from such a reflex.

Lesson Summary

The somatic nervous system (SNS) is the portion of the peripheral nervous system (PNS) related to voluntary muscle control. Two types of nerves are essential for the SNS: afferent (sensory) nerves that carry information from the body to the spinal cord and brain, and efferent (motor) nerves that relay information from the brain and spinal cord to the skeletal muscle. Spinal nerves originate from the spinal cord and carry sensory and motor information. Cranial nerves carry information to and from the brain.

Answer Key

Worksheet: Somatic Nervous System: Components & Functions

https://study.com/academy/lesson/somatic-nervous-system-components-functions.html

Which of these is considered a simple (monosynaptic) reflex?

• Knee jerk reflex
• Running
• Hand withdrawal reflex
• Walking

Which of these is NOT a function of the somatic nervous system?

• Knee jerk reflex
• Coordinated movement of the gastrointestinal system (peristalsis)

Which neurotransmitter causes skeletal muscle fibers to contract?

• Serotonin
• Acetylcholine
• Dopamine
• Epinephrine

Which of these would be considered an afferent component of the somatic nervous system?

• Thermoreceptors in the skin that relay temperature information
• Axons of motor neurons in the spinal cord synapsing on skeletal muscle fibers
• Motor neurons in the spinal cord
• Motor neurons in the brain

What type of information is carried by spinal nerves?

• Afferent
• Mixed (afferent and efferent)
• Afferent for some spinal nerves but efferent for other spinal nerves
• Efferent

What is Vagus Nerve?

The nervous system is the part of the body that originates in the brain and controls movements, thoughts, and automatic responses. Automatic responses are activities that do not require conscious thought, such as reacting by removing a finger from a hot stove or breathing. The image here shows the thousands of different nerves in the nervous system.

The nervous system is composed of a group of cells called neurons

The parasymphatetic nervous system is the part of the nervous system that conserves the body's natural activity by promoting relaxation and digestion after a stressful situation has passed. One of the main components of the parasympathetic nervous system is the vagus nerve.

Vagus nerve definition

The parasympathetic nervous system is mainly controlled by the agus nerve. The vagus nerve plays the important role of monitoring crucial body functions such as mood control, immune response, digestion, and heart rate.

Vagus Cranial Nerve

Cranial nerves are a set of 12 pairs of nerves connecting the brain to different parts of the head, neck, and body. This table shows the 12 cranial nerves and their function. Each of these nerves are pairs. One nerve is found on the right side of the body and its pair is on the left side of the body. For example, the vagus cranial nerve, also known as cranial nerve X, is the 10th pair of the cranial nerves with one nerve on each side of the body.

Cranial Nerve Number	Nerve	Function
CN I	Olfactory Nerve	Smell
CN II	Optic Nerve	Vision
CN III	Oculomotor Nerve	Eye movement; Pupil constriction
CN IV	Trochlear Nerve	Eye movement
CN V	Trigeminal Nerve	Sensory information: touch and pain from face/head; muscles for chewing
CN VI	Abducens Nerve	Eye movement
CN VII	Facial Nerve	Taste; Sensory information from ear; controls muscles in facial expression
CN VIII	Vestibulocochlear Nerve	Hearing and balance
CN IX	Glossopharzyngeal Nerve	Taste; sensory information from tongue, tonsils, pharynx; some muscles involved in swallowing
CN X	Vagus Nerve	Sensory; motor; digestion; heart rate; breathing
CN XI	Accessory Nerve	Muscles used for head and neck movement; shrugging
CN XII	Hypoglossal Nerve	Tongue muscles

Location of different cranial nerves

Vagus Nerve Anatomy

Nerves are categorized as sensory, motor, or mixed.Motor nerves transmit impulses from the brain and spinal cord to muscles. Sensory nerves move information such as heat, cold, and pain to the brain and spinal cord. Mixed nerves are composed of motor and sensory fibers.

Vagus nerve anatomy

The vagus nerve is the longest cranial nerve in the body. It is actually two nerves called the left and right vagus nerve. It is considered a mixed nerve because it contains both motor and sensory fibers. The word vagus means wandering in Latin. This nerve was named the vagus nerve because it wanders throughout the body. In other words, it has the widest distribution of all the other nerves in the body.

Vagus nerve physiology

The vagus nerve carries information between the brain and internal organs. The nerve alerts the brain about what is going on inside organs, specifically the digestive tract, lungs, heart, spleen, liver, and kidneys. The main function of the vagus nerve is to calm organs after stressful situations and adrenaline release.

Vagus Nerve Location

Where is the vagus nerve located?

The vagus nerve location originates in the brain and branches in different directions to the neck and trunk. Branches of the vagus nerve include:

• Auricular nerve
• Pharyngeal nerve
• Superior laryngeal nerve
• Superior cervical branches of the vagus nerve
• Inferior cervical cardiac branch
• Recurrent laryngeal nerve
• Thoracic cardiac branches
• Branches of the pulmonary plexus
• Branches to the esophageal plexus
• Anterior vagal trunk
• Posterior vagal trunk
• Herring breuer reflex in alveoli

Vagus Nerve Function

What is the function of the vagus nerve?

The vagus nerve functions to:

• Provide bodily sensation from the skin behind the ear, external ear canal, and parts of the throat
• Provide bodily sensation from the larynx, esophagus, lungs, trachea, and majority of the digestive tract
• Provide sensation of tastes near the root of the tongue
• Stimulate muscles in the pharynx, larynx, and soft palate
• Stimulate muscles in the heart to lower resting heart rate
• Stimulate involuntary contractions in the digestive tract allowing food to move

The vagus nerve is also important because it regulates internal organ function (digestion, heart rate, and respiratory rate), blood vessel dilation, and reflexes (coughing, sneezing, swallowing, and vomiting).

Vagus Nerve Pathway

The vagus nerve pathway starts in the brain and moves into the organs in the neck, chest, and abdomen and forms many branches along the way.

• The right vagus nerve branches to the right recurrent laryngeal nerve which ascends into the neck between the trachea and esophagus. It then runs along the superior vena cava to the right main bronchus. It forms the vagal trunk at the lower part of the esophagus and enters the diaphragm.
• The left vagus nerve enters the thorax and descends along the aortic arch where it branches into the left recurrent laryngeal nerve and moves between the trachea and esophagus. Additional thoracic branches continue into the esophageal plexus and enter the abdomen.

Vagus Nerve Innervation

The vagus nerve has two ganglia, or masses of nerve tissue: the superior and inferior ganglia. These ganglia innervate supply different areas of the body with nerves.

Branches of the superior ganglion innervate the skin in the ear. The inferior ganglion branches into the pharyngeal nerve and superior laryngeal nerve. The laryngeal nerve innervates the muscles of the voice box.

The vagus also branches to innervate cardiac, esophageal, and pulmonary areas and the greater part of the digestive tract in the abdomen.

The vagus nerve controls many important body functions like breathing, talking, and sweating. Since the vagus nerve innervates the esophagus, it is also involved in peristalsis. Peristalsis is a process by which muscles in the digestive system contract in order to move food down the digestive tract.

Vagus Nerve Damage

Vagus nerve damage can result in the following:

• Difficulty speaking
• Loss or change of voice
• Difficulty of swallowing
• Loss of gag reflex
• Low blood pressure
• Slow heart rate
• Changes in digestion
• Nausea or vomiting
• Abdominal bloating or pain
• Depression and anxiety coupled with breathing problems or heart disease

Gastroparesis is a condition in which involuntary contractions prevent the stomach from emptying properly. A person with gastroparesis may have symptoms of nausea, vomiting, feeling full easily, and having a slowly emptying stomach. There are different factors that can cause gastroparesis. One factor is damage to the vagus nerve since it is involved in digestion.

When the vagus nerve is not functioning properly a heightened sense of stress may occur and result in anxiety.

Vagus Nerve Stimulation

In vagus nerve stimulation, a device is used to send electrical impulses to the nerve. One method of vagus nerve stimulation involves an implanted device under the skin. In this method, a wire connected to the device under the skin runs to the vagus nerve. When the device is activated, an electrical signal is sent to the vagus nerve. In this type of treatment, the left vagus nerve is stimulated. Stimulation of the right vagus nerve is avoided since the right nerve can branch to the heart.

Vagus nerve stimulation may help reduce epileptic seizures in people who have not responded to anti-seizure drugs. It can also be helpful for people who have not responded to intensive depression treatments. Research is being done on using vagus stimulation to treat headaches, rheumatoid arthritis, inflammatory bowel disease, bipolar disorder, obesity, and Alzheimer's disease.

Lesson Summary

The nervous system is the part of the body that originates in the brain and controls movements, thoughts, and automatic responses. The parasymphatetic nervous system is the part of the nervous system that conserves the body's natural activity promoting relaxation and digestion after stressful situations. The parasympathetic nervous system is mainly controlled by the vagus nerve. The vagus nerve plays the important role of monitoring crucial body functions such as mood control, immune response, digestion, and heart rate. Cranial nerves are a set of 12 pairs of nerves connecting the brain to different parts of the head, neck, and body. The vagus cranial nerve, also known as cranial nerve X, is the 10th pair of cranial nerves with one nerve on each side of the body.

Nerves are categorized as sensory, motor, or mixed. Motor nerves transmit impulses from the brain and spinal cord to muscles. Sensory nerves move information such as heat, cold, and pain to the brain and spinal cord. Mixed nerves are composed of motor and sensory fibers. The vagus nerve is the longest cranial nerve in the body and is considered a mixed nerve because it contains both motor and sensory fibers. It has two ganglia that innervate, or supply different areas of the body with nerves such as the skin in the ear, muscles of the voice box, esophagus, heart, and digestive tract in the abdomen. Peristalsis is a process by which muscles in the digestive system contract in order to move food down the digestive tract. Gastroparesis is a condition that can result when the vagus nerve is damaged. In this condition, the stomach does not empty properly.

Frequently Asked Questions

Where does the vagus nerve go?

The vagus nerve pathway starts in the brain and moves into the organs in the neck, chest, and abdomen. The vagus nerve forms many branches along the way.

What happens when you stimulate the vagus nerve?

In vagus nerve stimulation, a device is used to send electrical impulses to the nerve. The vagus nerve may be stimulated to reduce epileptic seizures in people who have not responded to anti-seizure drugs.

Why is the vagus nerve so important?

The vagus nerve is the main component of the parasympathetic nervous system. It oversees crucial body functions such as mood control, immune response, digestion, and heart rate.

How does the vagus nerve affect anxiety?

The vagus nerve is involved in calming the body. When the vagus nerve is not functioning properly, a heightened sense of stress may occur and result in anxiety.

What side of the body is the vagus nerve on?

The vagus nerve is a pair of nerves. The vagus cranial nerve, also known as cranial nerve X, is the 10th pair of cranial nerves with one nerve on each side of the body.

What are the symptoms of vagus nerve damage?

Vagus nerve damage can cause different symptoms, including: