EXAM 3 STUDY GUIDEANS- (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” isa term that is used during lecture that refers to internal organs, abdominal & thoracic cavitiesFirst we need to understand how the ANS (autonomic nervous systems) differs fromthe 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 hugerole 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 gangliaNeurotransmitters 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 stimulationOkay, 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 byinhibiting 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 Stimualtion from midbrain..Ach goes to heart (inhibition occurs) and also goes to gasto/intestinal organs (stimulation takes place) 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 fromsympathetic 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 innervationAcetylcholine(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 systemThe 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 andmobilizes fat as an energy sourceAlthough the parasympathetic nervous system slows the heart and stimulates digestive/urinary systems the division of the sympathetic can override the usual parasympathetic affect during STRESSTHE 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
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