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By the end of this section, you will be able to:
  • Name the components that generate the sympathetic and parasympathetic responses of the autonomic nervous system
  • Explain the differences in output connections within the two divisions of the autonomic nervous system
  • Describe the signaling molecules and receptor proteins involved in communication within the two divisions of the autonomic nervous system

The nervous system can be divided into two functional parts: the somatic nervous system and the autonomic nervous system. The major differences between the two systems are evident in the responses that each produces. The somatic nervous system causes contraction of skeletal muscles. The autonomic nervous system controls cardiac and smooth muscle, as well as glandular tissue. The somatic nervous system is associated with voluntary responses (though many can happen without conscious awareness, like breathing), and the autonomic nervous system is associated with involuntary responses, such as those related to homeostasis.

The autonomic nervous system regulates many of the internal organs through a balance of two aspects, or divisions. In addition to the endocrine system, the autonomic nervous system is instrumental in homeostatic mechanisms in the body. The two divisions of the autonomic nervous system are the sympathetic division    and the parasympathetic division    . The sympathetic system is associated with the fight-or-flight response    , and parasympathetic activity is referred to by the epithet of rest and digest    . Homeostasis is the balance between the two systems. At each target effector, dual innervation determines activity. For example, the heart receives connections from both the sympathetic and parasympathetic divisions. One causes heart rate to increase, whereas the other causes heart rate to decrease.

Watch this video to learn more about adrenaline and the fight-or-flight response. When someone is said to have a rush of adrenaline, the image of bungee jumpers or skydivers usually comes to mind. But adrenaline, also known as epinephrine, is an important chemical in coordinating the body’s fight-or-flight response. In this video, you look inside the physiology of the fight-or-flight response, as envisioned for a firefighter. His body’s reaction is the result of the sympathetic division of the autonomic nervous system causing system-wide changes as it prepares for extreme responses. What two changes does adrenaline bring about to help the skeletal muscle response?

Sympathetic division of the autonomic nervous system

To respond to a threat—to fight or to run away—the sympathetic system causes divergent effects as many different effector organs are activated together for a common purpose. More oxygen needs to be inhaled and delivered to skeletal muscle. The respiratory, cardiovascular, and musculoskeletal systems are all activated together. Additionally, sweating keeps the excess heat that comes from muscle contraction from causing the body to overheat. The digestive system shuts down so that blood is not absorbing nutrients when it should be delivering oxygen to skeletal muscles. To coordinate all these responses, the connections in the sympathetic system diverge from a limited region of the central nervous system (CNS) to a wide array of ganglia that project to the many effector organs simultaneously. The complex set of structures that compose the output of the sympathetic system make it possible for these disparate effectors to come together in a coordinated, systemic change.

Questions & Answers

what is the difference between a neuron and nerve?
Tonny Reply
Neurons are specialized cells which are capable of transmitting signals between different parts of the body. Nerve is a bundle of fibers composed of neurons. Therefore, neurons and nerves are closely related.
acquosuah
wow
Andy
what are the first aid procedures
Andy
immediately care to prevent further injury
Vandana
what is a positive and negative feedback and give examples of both positive and negative feedback
esther Reply
Positive feedback is a feedback that tends to magnify its output. An example of positve feedback is the release of oxytocin from the pitutary gland during child birth. Negative feedback regulates a stimulus to cause a opposite effect. An example of this is when you eat your blood sugar rises,which
Camello
is sensed by the nervous system. specialized cells in the pancreas sense the increase and release the hormone insulin.
Camello
merci beaucoup
esther
what then is Pathological anatomy
acquosuah Reply
anatomy study about normal human organ... pathological anatomy study of diseased organ
Aswin
thanks
acquosuah
wow
Morshed
that's are good
Morshed
why oral glucose make insulin response in 1 phase but IV glucose make insulin response in 2 phase?
qwe Reply
what is anatomical position?
Kakande Reply
it's de description of any region or part of the body in specific strance
Andy
the standard anatomical position is standing straight with your hand an feet forward and the neck straight and face facing forward
Lubabah
how many cell do we have in our body
Sawmtei Reply
around 37.2 trillion
Jeremiah
how do you know when a women is lying
Hernandez
go with your gut
Stephanie
what is a positive and negative feedback and give examples of negative and positive feedback
esther Reply
messa I didn't understand this too
Shammy
and would love to know as well
Shammy
what are the various types of white blood cells
Andy Reply
what is cpr in first aid
Andy
various whiteblood cells includes Granulocytes (neutrophils,basophils ana eosinophils) and Agranulocytes (monocytes and lymphocytes)
Waziri
Cardiopulmonary resuscitation (cpr) is an emergency procedure. Uses chest compressions with artificial ventilation in an effort to preserve brain function until further measures are taken to restore blood circulation and breathing in a person who is in cardiac arrest.
Jeremiah
wow thanks alot
Andy
respiration is not just taking in of oxygen and bringing out Co2. that is called INHALATION AND EXHALATION. BUT RESPIRATION IS THE BREAKDOWN OF LARGE MOLECULES OF GLUCOSE OR OTHER SUBSTRATES IN THE PRESENCE OF OXYGEN AND SUBSEQUENT REMOVAL OF WASTE PRODUCT
Osuji Reply
why study anatomy?
esther Reply
to know the detailed functioning of the internay body organs
Jam
we study anatomy to know about the structure of the organs which in turn help to study physiology which is the knowledge related to function of the vital organ,and when we know the normal functionality we can understand the abnormalities in that organ,and the study of disease is called pathology
Lubabah
why is it so hard to know the spelling and words
Sawmtei
they were made so that only the best and thr brightest would understand.
Senen
thank you
esther
to know the internal structure of the human body and how it function
Jaafar
whats antonmy
Jaan Reply
the study of structure and function of internal body parts
Jam
is a branch of biology which describes the structures of the body and relationship from one part to another
esther
I believe it is the scientific study of body structures that are both macro and micro.
acquosuah
wat the question is tis ! without knowing tis simple thing.. y didn't install tis app ..
Aswin
what is anatomy and physiology
mwitwa Reply
Anatomy is the study of structures of the body
Zunehri
Physiology the study functions of the body
Zunehri
anatomy is study of structure of body nd physiology is study of function of body.
PRIYANKA
anatomy is the study of internal body structures and physiology is the functioning of these structures in the body
Jam
what is lungs
Shipon Reply
it an organ found in our thoracic cavity
Richard
lungs are spongy organs where our respiration takesplace
Maryama
Lungs is a spongy organs located in the chest , is an a primary organs of respiration in human body and other Animals
Zunehri
lungs thorex me present hote hai ye organ hai and gas exchange (o2,co2 exchange)inka inka function hai.
PRIYANKA
lungs ka function hai
OM
pls am a student I don't know
Mavis
main function is respiration
faheem
respiration is the taking ing of oxygen by the body tissues and the removal of carbondioxide from the body tissues
Jam
what is heart beat,?
Naqeeb Reply
heart beat is the process briting
Mavis
what functions of heart
Muthu Reply
To circulate the blood
Arshad
it pump blood to the lungs
Laura
very twiest
Shipon

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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