sympathetic system

Examples of sympathetic 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).
  • Therefore, this response that acts primarily on the cardiovascular system is mediated directly via impulses transmitted through the sympathetic nervous system and indirectly via catecholamines secreted from the adrenal medulla.
  • The sympathetic nervous system is said to have "thoracolumbar outflow" based on its location.
  • 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.

• 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.
  • The sympathetic division typically functions in actions requiring quick responses.
  • Distinguish between the parasympathetic and sympathetic subsystems of the autonomic nervous system

• 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.
  • This response acts primarily on the cardiovascular system and is mediated directly via impulses transmitted through the sympathetic nervous system and indirectly via catecholamines such as adrenaline secreted from the adrenal medulla.
  • CRH gets transported to the anterior pituitary through the circulatory system and vasopressin is transported by axonal transport to the anterior pituitary.
  • Distinguish between the nervous system and endrocrine system responses to stress

• Parasympathetic Responses

  • 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.
  • Sympathetic and parasympathetic divisions typically function in opposition to each other.
  • The sympathetic nervous system can be considered a quick response, mobilizing system; and the parasympathetic a more slowly activated dampening system.
  • The sympathetic division typically facilitates quick responses.

• 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

• Autonomic Reflexes

  • 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.
  • The ANS is classically divided into two subsystems: the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS) which operate independently in some functions and interact co-operatively in others.
  • An older simplification of the sympathetic and parasympathetic nervous systems as "excitatory" and "inhibitory" was overturned due to the many exceptions found.
  • A more modern characterization used is that the sympathetic nervous system is a "quick response mobilising system" and the parasympathetic is a "more slowly activated dampening system"; but even this also has exceptions, such as in sexual arousal and orgasm where both play a role.
  • This schematic (but not anatomically correct) depiction of a typical spinal nerve indicates (1) somatic efferent fibers, (2) somatic afferent fibers, (3-5) sympathetic efferent fibers, and (6,7) sympathetic afferent fibers.

• Parasympathetic (Craniosacral) Division

  • Each has three roots entering the ganglion (motor, sympathetic, and sensory roots) and a variable number of exiting branches.
  • The sympathetic root carries postsynaptic sympathetic fibers (general visceral efferent fibers) that traverse the ganglion without synapsing.
  • 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 Plexuses

  • Autonomic plexuses are formed from both sympathetic and parasympathetic fibers and innervate visceral organs to regulate overall activity.
  • The nerves in the each plexus are close to each other, as in the plexuses of the somatic nervous system, but typically do not interact or synpase together.
  • Instead they provide a complex innervation pattern to the target organs, since most organs are innervated by both divisions of the autonomic nervous system.
  • Pulmonary: The pulmonary plexus is an autonomic plexus formed from pulmonary branches of vagus nerve and the sympathetic trunk.
  • This section of the sympathetic trunk shows both the celiac and the hypogastric plexus.