A clear understanding of the autonomic nervous system is imperative to understanding physiological responses within the body. This assignment asks you to identify the features of the sympathetic and parasympathetic divisions of the autonomic nervous system that would allow us to distinguish one division from the other. This assignment will help you to apply this week’s reading content.

The sympathetic nervous system activates the 'fight or flight' response in an individual by releasing the hormones epinephrine and norepinephrine. These hormones increase the rate of the heart, respiration and dilates the pupils. This system is located in the spinal cord near the lumbar and thoracic area.

The parasympathetic nervous system found between the spinal cord and medulla, it activates the 'rest and digest' response by releasing the hormone acetylcholine, this hormone slows the heart rate as well as the respiration rate.

Explanation:

The Autonomic nervous system, is a branch of peripheral nervous system (PNS)  which  controls involuntary activities of the body and the complimentary damping effects.Thus heart rate, response to fight-or flight stimulus,arousal, from sleep,  digestion, breathing  all are controlled by the ANS. Its control center in the brain is the Hypothalamus.

Sympathetic and Parasympathetic nervous systems(SNS&PSN) respectively  are branches of ANS.while the SNS   coordinate  fast- response pathways to  involuntary stimuli. thus it is usually  refereed to as fight or flight system. The PNS  is concerned with coordination of complimentary counter quick response to slowdown the effects of the quick response.

Based on orgin;

The PSN originated from the cranial and sacral region of the CNS system while; the SNS  originated from the cranial, thoracic ,lumbar regions. The proximity to the SNS to these regions explains the reason  for its regulation of digestion, respiration, urination, breathing,and other involuntary activities associated with these regions.

Ganglion distribution.

The PNS ganglion are located close to the effectors away from the CNS (Thus this explains the long-preganglion fibres, and short post-ganglion fibres of PNS.) The proximity  with  the effectors  is to synapse quickly  to bring into effects  the motor response needed to  counter the  fast exitatory stimulation of the SNS at the effectors;e,g muscles.However SNS ganglion (shrot pre-ganlion fibres are in the CNS close to its control center in the medulla to coordinate fast response to rapid stimuli , to ensure effective response by the body,

Hormone influences

SNS  stimulates and  mediates the release of  adrenaline from adrenal glands  in response to fight or flight stimuli.This is needed to prepare the body for quick rapid response to danger or need for escape. However, the PNS has no effect on  hormone release but maintain return of the body to normal physiological state after the effects of adrenaline

Homeostatic effects

Most excitatory homeostatic effects of the body are controlled the SNS.(thus the need to raise the water potential of the blood during dehydration is due to the excitatory effects of SNS to stimulate the release of ADH.) However the complimentary  inhibitory effects to calm this down is coordinated by the  PNS.

Thus while SNS increases heartbeat,heart-rate, adrenaline levels, metabolic rate, breakdown of glucose, through  diffused  effects at the target areas in repose to fast involuntary stimuli,

PNS,  maintained  a decrease in all these activities, by bringing   calming effects at the localized area(effector).

Explanation: