Sympathetic Nervous System Case Study

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1. A salivary gland is stimulated by its parasympathetic nerve.
a) Describe the organization of the parasympathetic division of the autonomic nervous system
The autonomic nervous system (ANS) is a part of the peripheral nervous system that largely acts involuntarily. It consists of nerves in cardiac muscle, smooth muscle, exocrine and endocrine glands. The main visceral activities are temperature regulation, digestion, blood pressure and genitourinary function. The second main division of the peripheral nervous system is the somatic nervous system. This consists of cranial and spinal nerves that innervate skeletal muscle tissue and have a more voluntary control function. The ANS has two peripheral components, a motor efferent system and a sensory afferent system.
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The parasympathetic division, is associated with actions that conserve and restore energy. It is central during rest, sleeping, digesting food, lowering metabolic rate and restoring blood pressure and resting heartbeat. The parasympathetic system is also referred to as the craniosacral system i.e. preganglionic neurons leaving the brain via the cranial nerves and also leaving the spinal cord via the sacral nerves. Preganglionic neurons have long axons. Postganglionic neurons have short axons that terminate in the organ being innervated. The cranial nerves that are involved in the parasympathetic system include the following:
• Oculomotor Nerve (III): target is the eye. Preganglionic neurons originate in accessory occulomotor nucleus, postganglionic neurons originate in ciliary ganglion. Its parasympathetic nerve fibers control the muscles that dilate or constrict the pupils. They also control the muscles that change the shape of the lens to allow the eyes to focus on near or far

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