Autonomic Nervous System

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The two divisions of the autonomic nervous system (ANS), sympathetic (SNS) and parasympathetic (PNS), function in a complementary and integrated manner to maintain homeostasis. The output of the autonomic nervous system is quick in comparison to the endocrine system functions. In most cases, these systems have opposite effects, where one initiates a physiological response and the other inhibits. The nerves of this system regulate vital internal functions which are generally performed without conscious control (Khan Academy, 2014). The output of the ANS effects smooth, cardiac muscle and glandular tissue (Betts et al, 2013) The sympathetic division is associated with the “fight or flight” response, dominating in stressful situations…show more content…
The synapse at the axon terminal of the postganglionic neuron and the target effector cell (in the form of muscle or gland) uses epinephrine/norepinephrine (adrenaline/noradrenaline) (AK Lectures, 2014) The parasympathetic division however, is concerned with “rest and digest” responses and when active, reverses the effects of the SNS. The PNS system increases blood flow to digestive organs and excretory system and decreases the blood flow to skeletal tissue (an opposite effect to the SNS) (AK Lectures, 2014) Salivary secretion is increased and gastric motility is stimulated to facilitate digestion (McCorry, 2007). The PNS either originates at the start of the spinal cord or at the end (Khan Academy, 2014). The preganglionic neuron is of long structure and uses acetylcholine to transmit signals to the shorter postganglionic neuron. The postganglionic neuron continues to use acetylcholine to transmit to the target effector cell (AK Lectures, 2014) Question 2 (1.3) Using Illustrations, and a short commentary, describe the sensory and motor neuron. Figure 1- A Motor Neuron (Biologymad, n.d.) Figure 2- A Sensory Neuron (Biologymad, n.d.) (200) Sensory neurons are unipolar (Betts et al, 2013) Sensory (afferent) neurons transmit impulses from sensory receptors to the CNS and Motor (efferent) neurons transmit impulses from the CNS to effector muscle and
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