EXAM 3 STUDY GUIDE ANS Independent Autonomic Nervous System this is the other part of the peripheral nervous system the part we already learned is the somatic nervous system SNS ANS basically controls smooth muscle internal organs in that motor neurons innervate innervate means a nerve controls a cell smooth muscle in organs like the heart blood vessels bladder and gastrointestinal system viscera is a term that is used during lecture that refers to internal organs abdominal thoracic cavities First we need to understand how the ANS autonomic nervous systems differs from the SNS somatic nervous system EFFECTORS ANS cardiac muscle smooth muscle and glands the effector of the SNS is skeletal muscle an effector is the specific tissue being stimulated by the ANS ANS targets the heart and organs SNS targets skeletal muscles EFFERENT PATHWAYS ANS has a TWO neuron chain this means that the autonomic nervous system needs two neurons to connect to the organ This two neuron chain is made up of the pre ganglionic neuron has lightly myelinated axon and then the post ganglionic neuron the second neuron that extends to an effector organ So inside of one ganglia you have the axon terminal of the pre ganglionic neuron and the soma of the post ganglionic neuron So remember that for the ANS 1 SYNAPSE 2 NUERONS 1 GANGLIA ANS is divided into the sympathetic nervous system and the parasympathetic nervous system these systems are in sync to counterbalance the activity of one another ultimately playing a huge role in homeostasis Sympathetic fibers increase heart and respiratory rates and inhibit digestion and elimination Parasympathetic fibers decrease heart and respiratory rates and allow for digestion and the discarding of wastes Anatomy of ANS Parasympathetic CRANIOSACRAL division long pre ganglionic nerve before synapse short post ganglionic nerve after synapse this is opposite for Sympathetic Vagus Nerve aka X its soma extends from medulla oblongata most pre ganglionic parasympathetic neurons extend from here and the rest extend from sacral part of craniosacral division Sympathetic pre ganglionic neurons located from T1 to L2 the THORACOLUMBAR division The adrenal gland part of kidneys is ONLY innervated by sympathetic no post ganglionic neuron collateral ganglia farther away from vertebrae sympathetic ganglia that is unpaired and located between the chain and the organ sympathetic chain ganglia paired parallel to one another these pairs can be seen on the below diagram from T1 to L2 T5 L2 splanchnic nerves synapse with collateral ganglia Neurotransmitters and Receptors acetylcholine Ach and Norepinephrine NE are two major neurotransmitters cholinergenic fibers are fibers that release Ach Ach receptors are located on all organ cells and are stimulated by postganglionic fibers the effect of Ach binding can be either inhibitory or excitatory For example in the thoracic cavityAch will produce inhibition abdominal cavity Ach abdomen will produce stimulation Okay Soooo this is how I think about it the Sympathetic ANS 1 realeases Norepinephrine NE to its organs and 2 stimulates the thoracic cavity and inhibits the abdominal cavity Therefore any organ in the thoracic cavity must be stimulated by NE and any organ in the abdominal cavity must be inhibited by NE Furthermore since NE stimulates the thoracic cavity Ach must counterbalance that by inhibiting it Same goes for the Abdominal cavity if NE inhibits it then Ach must stimulate it IN A NUT SHELL NE of Symp stimulates thoracic cavity inhibits abdominal cavity Ach of ParaSymp inhibits thoracic cavity stimulates abdominal cavity occurs and also goes to gasto intestinal organs stimulation takes place Stimualtion from midbrain Ach goes to heart inhibition The stimulation of adrenergic receptors is opposite adrenergic receptors are in response to Catecholamines Sympathetic Nervous System Adrenergic fibers sympathetic post ganglionic axons that release norepinephrine Catecholamine group of chemical substances epinephrine EPI and norepinephrine NE can serve as hormones and neurotransmitters Postganglionic sympathetic neurons are the only onex that secretes catecholamines The soma of sympathetic post ganglionic neurons can produce catecholamines Adrenal glands receive Ach from pre ganglionic axons tissue of adrenal medulla and sympathetic post ganglionic neurons are the same tissue Adrenal medulla and post ganglionic neuron both release catecholamines catecholamine from the adrenal medulla are hormones and catecholamines from sympathetic post ganglionic neurons are neurotransmitters The adrenal medulla is a part of both the ANS autonomic and the ENS endocrine adroneurgic Adrenergic receptors alpha stimulatory and beta inhibitory An example of sympathetic stimulation with exercise heart rate increases Blood vessels and ventricles heart ONLY sympathetic innervation atrium BOTH Most blood vessels have NO parasympathetic innervation Acetylcholine Ach and Catecholamines Ach cholinergenic Catecholamines norepinephrine and epinephrine Ach inhibits the hear catecholamines aka NE EPI stimulate the heart Parasympathetic inhibits heart and stimulates abdomen Sympathetic stimulates the heart and inhibits abdomen Again these are opposite of each other the counterbalance each other An important thing to remember about Parasympathetic neurons is that the Vagus nerve innervates the atrium of the heart and the gastrointestinal system The Sympathetic division is fight or flight system and can regulate functions not subject to parasympathetic influence adrenal medulla sweat glands kidneys most bloods vessels The division of the sympathetic nervous system in for a excitement emergency embarrassment exercise basically think STRESS this division increases metabolic rate raises blood glucose levels and mobilizes fat as an energy source Although the parasympathetic nervous system slows the heart and stimulates digestive urinary systems the division of the sympathetic can override the usual parasympathetic affect during STRESS THE ENDOCRINE SYSTEM response occur slowly but last longer than those of nervous system works with nervous system to regulate body cell activity Remember that the hypothalamus belongs to the nervous system but secretes hormones that control endocrine system Endocrine gland info The most important PURE ENDOCRINE gland is the pituitary gland adrenal medulla nervous and endocrine system outside the adrenal medulla is the adrenal cortex which secretes many different
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