KIN 292 1nd Edition Lecture 18 These are the notes from Professor Starnes lecture of Clinical Human Physiology These come from the slideshows provided by the professor and include extra notes and explanations Highlighted or bolded information are things that I believe to be information that is important to look over multiple times The notes in red are my personal additions and quotes of Professor Starnes from the class lecture Outline of Last Lecture I Chapter 10 10 1 and 10 2 II Exam 2 Outline of Current Lecture I 11 1 The Autonomic Nervous System II 11 2 The Somatic Nervous System Current Lecture Autonomic and Motor Systems the efferent branch of PNS Composed of The Autonomic Nervous System regulates the function of most of your effector organs without your control or knowledge Also referred to as the involuntary system for lack of volition The Somatic Nervous System controls only skeletal muscle function and it is under your control Volition definition the act of willing choosing or resolving 11 1 The Autonomic Nervous System Outline Dual innervation in the autonomic nervous system Two opposing divisions or branches innervate most organs Anatomy of the autonomic nervous system Regulation of autonomic function Autonomic neurotransmitters and receptors Autonomic neuroeffector junctions These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Autonomic nervous system is under dual innervation from sympathetic and parasympathetic divisions Neuron origins o Sympathetic Thoracolumbar o Parasympathetic Craniosacral Primary function regulate organs to maintain homeostasis Parasympathetic rest Sympathetic fight or flight response Two types of neurons from CNS to effector organs Preganglionic CNS to autonomic ganglion Postganglionic autonomic ganglion to organ Autonomic ganglia are busy communication centers o A preganglionic neuron synapses with many postganglionic neurons Ganglia also contain intrinsic neurons that modulate information being sent to effector organs 3 neural anatomy patterns in the sympathetic nervous system 1 Sympathetic chain Ganglia connected by preganglion collaterals Allows for simultaneous activation of many organs 2 Direct to modified postganglion cells endocrine in adrenal medulla Fig 11 5 3 Travel through sympathetic chain without forming a synapse Forms synapses in one of 3 collateral ganglia that innervate only selected target organs Allows for more discrete or specific results compared to 1 2 above Parasympathetic nervous system pathways Long preganglionic neurons directly to ganglia near the effector organ Short postganglionic neurons Cranial nerves see Fig 11 1 o Cranial nerve X vagus nerve much of viscera o Cranial nerve III oculomotor smooth muscle in pupil and lens o Cranial nerve VII facial nerve salivary glands o Cranial nerve IX glossopharyngeal nerve smooth muscle in throat and viscera of thorax and abdomen The Mixed Composition of Autonomic Nerves Nerve o Definition A bundle of axons fibers in the PNS connects the CNS with organs in the periphery Autonomic nerves have o Fibers sending action potentials in two directions o Efferent fibers to regulate effector organs and o Afferent fibers from visceral receptors to CNS Important in maintaining homeostasis Regulation of Autonomic Function Dual innervation of organs both sympathetic and parasympathetic nerves Visceral receptors within body send afferent signals to specific locations in the brain which process the information and decide how much sympathetic and parasympathetic activity is required to maintain homeostasis in each organ at any particular moment or activity Increases in parasympathetic activity are coupled with decreases in sympathetic activity and vice versa Autonomic reflex response that controls blood pressure when a person stands up An example Regulation General Process Visceral receptors send afferent signals to specific locations in the brain which process the information and decide how much sympathetic and parasympathetic activity is required to maintain homeostasis in each organ at any particular moment or activity Regulation of Autonomic Function Parasympathetic activity o Quiet relaxed states o Active in rest and digest o Increases gastrointestinal activities o Decreases heart rate and blood pressure Sympathetic activity o Fight or flight response o Prepares for emergency stress and exercise o Increases heart rate and blood pressure o Mobilizes energy stores o Dilates pupils o Decreases gastrointestinal and urinary functions Tonic Activity at Rest Both branches active Parasympathetic nervous system dominates Endurance exercise training enhances the parasympathetic domination at rest and during light exercise intensities resulting in lower resting heart rate and some other changes Autonomic Neurotransmitters and Receptors Types of cholinergic receptors Types of adrenergic receptors Neurotransmitters of the Autonomic Nervous System Preganglionic neurons o Acetylcholine Parasympathetic postganglionic neurons o Acetylcholine Sympathetic postganglionic neurons o Norepinephrine Hormones of the adrenal medulla secreted to blood o 80 epinephrine o 20 norepinephrine Types of Cholinergic Receptors Nicotinic cholinergic receptors ionotropic o Cause cation channels to open o Channel opening results in depolarization Muscarinic cholinergic receptors metabotropic o G protein coupled o Effect depends on target cell Types of Adrenergic Receptors Two main classes alpha and beta Each has subclasses All are coupled to G proteins Alpha Receptors o Alpha 1 1 o Alpha 2 2 Beta Receptors o Beta 1 1 o Beta 2 2 o Beta 3 3 Specific drugs target specific receptors to treat specific clinical issues Autonomic Neuroeffector Junctions Synapses between efferent neuron and effector organ in the autonomic nervous system Neuroeffector junction o Between postganglionic neuron and effector organ o Neurotransmitter stored in axon swellings Varicosities Released in response to action potential in postganglionic neuron Neuroeffector junctions synapses at effector organs in autonomic nervous system Neurotransmitter release from varicosities Release mechanism is very similar to that of a normal axon terminal Exceptions 1 NT released from all vericosities each one is similar to a terminal 2 Distance between varicosities and organ are greater than the width of a synaptic cleft which means the NT diffuses further and can bind