sympathetic nervous system

(noun)

The part of the autonomic nervous system that under stress raises blood pressure and heart rate, constricts blood vessels, and dilates the pupils.

Related Terms

Examples of sympathetic nervous system in the following topics:

  • Sympathetic Nervous System

    • Sympathetic ganglia are the ganglia of the sympathetic nervous system that initiate "fight-or-flight" or stress-mediated responses.
    • Sympathetic ganglia are the ganglia of the sympathetic nervous system (see , red fibers).
    • The sympathetic nervous system is said to have "thoracolumbar outflow" based on its location.
    • The parasympathetic nervous system, shown in blue, is a division of the autonomic nervous system.
    • Describe the features of the sympathetic division of the autonomic nervous system

  • Sympathetic Responses

    • The sympathetic division of the autonomic nervous system maintains internal organ homeostasis and initiates the stress response.
    • Alongside the other two components of the autonomic nervous system, the sympathetic nervous system aids in the control of most of the body's internal organs (see ).
    • The sympathetic nervous system is responsible for regulating many homeostatic mechanisms in living organisms.
    • Some evolutionary theorists suggest that the sympathetic nervous system operated in early organisms to maintain survival since the sympathetic nervous system is responsible for priming the body for action.
    • His theory states that animals react to threats with a general discharge of the sympathetic nervous system, priming the animal for fighting or fleeing.

  • The Stress Response

    • The body's stress response is mediated by the sympathetic nervous system and the hypothalmic-pituitary-adrenal (HPA) axis.
    • The body's stress response is mediated by interplay between the sympathetic nervous system (SNS) and the hypothalmic-pituitary-adrenal (HPA) axis .
    • The sympathetic nervous system participates in the regulation of many homeostatic mechanisms in living organisms.
    • Evolutionary theorists hypothesize that the sympathetic nervous system operated in early organisms to maintain survival as the sympathetic nervous system is responsible for priming the body for action.
    • Distinguish between the nervous system and endrocrine system responses to stress

  • Divisions of the Autonomic Nervous System

    • The autonomic nervous system (ANS) contains two subdivisions; the parasympathetic (PSNS) and sympathetic (SNS) nervous systems.
    • The autonomic nervous system (ANS) is classically divided into two subsystems (see : the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS).
    • The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system.
    • In the autonomic nervous system, preganglionic neurons connect the CNS to the ganglion.
    • Distinguish between the parasympathetic and sympathetic subsystems of the autonomic nervous system

  • Parasympathetic Responses

    • The parasympathetic nervous system (PSNS, or occasionally PNS) is one of the two main divisions of the autonomic nervous system (ANS) (shown in ).
    • The autonomic nervous system (ANS, or visceral nervous system, or involuntary nervous system) is the part of the peripheral nervous system that acts as a control system, functioning largely below the level of consciousness and controlling visceral functions.
    • Its action is described as being complementary to that of one of the other main branches of the ANS, the sympathetic nervous system, which is responsible for stimulating activities associated with the "fight or flight" response.
    • The sympathetic nervous system can be considered a quick response, mobilizing system; and the parasympathetic a more slowly activated dampening system.
    • The parasympathetic nervous system, shown in blue, is a division of the autonomic nervous system.

  • Comparing the Somatic and Autonomic Nervous Systems

    • The peripheral nervous system (PNS, see ) is divided into the somatic nervous system and the autonomic nervous system.
    • The somatic nervous system (SoNS) is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles.
    • The somatic nervous system consists of three parts:
    • It is classically divided into two subsystems: the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS).
    • The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system.

  • Autonomic Nervous System (ANS)

    • The autonomic nervous system is a part of the peripheral nervous system that controls visceral functions such as heart rate and digestion.
    • The autonomic nervous system (ANS or visceral nervous system or involuntary nervous system) is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness and controls visceral functions .
    • It is classically divided into two subsystems: the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS).
    • The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system.
    • Stimulation of the enteric nerves by the sympathetic system inhibits GI activity.

  • Parasympathetic (Craniosacral) Division

    • Parasympathetic ganglia are the autonomic ganglia of the parasympathetic nervous system which lie near or within the organs they innervate.
    • Parasympathetic ganglia are the autonomic ganglia of the parasympathetic nervous system, blue fibers).
    • Because of its location, the parasympathetic system is commonly referred to as having "craniosacral outflow," which stands in contrast to the sympathetic nervous system, which is said to have "thoracolumbar outflow."
    • The parasympathetic nervous system, shown in blue, is a division of the autonomic nervous system.
    • Describe features of the parasympathetic division of the autonomic nervous system

  • Preganglionic Neurons

    • In the autonomic nervous system (ANS), nerve fibers that connect the central nervous system to ganglia are known as preganglionic fibers.
    • In the autonomic nervous system (ANS), fibers from the central nervous system to the ganglion are known as preganglionic fibers.
    • All preganglionic fibers, whether they are in the sympathetic nervous system (SNS) or in the parasympathetic nervous system (PSNS), are cholinergic - that is, these fibers use acetylcholine as their neurotransmitter - and are myelinated.
    • Sympathetic preganglionic fibers tend to be shorter than parasympathetic preganglionic fibers because sympathetic ganglia are often closer to the spinal cord while parasympathetic preganglionic fibers tend to project to and synapse with the postganglionic fiber close to the target organ.
    • The site of synapse formation and this divergence for both the sympathetic and parasympathetic preganglionic neurons does however, occur within ganglia situated within the Peripheral nervous system.

  • Autonomic Interactions

    • The sympathetic and parasympathetic autonomic nervous systems cooperatively modulate internal physiology to maintain homeostasis.
    • Example processes that are modulated by the sympathetic and parasympathetic systems and are not easily labeled as "fight" or "rest" include the maintenance of blood pressure when standing and the maintenance of regular heart rhythms.
    • Some typical actions of the sympathetic and parasympathetic systems are listed below.
    • In the autonomic nervous system, preganglionic neurons connect the CNS to the ganglion.
    • Describe the interactions between the sympathetic and parasympathetic divisions of the autonomic nervous system