BIOL 252 1st Edition Lecture 4 Outline of Last Lecture I Intro to Intracellular Communication II How Action Potentials Work III Refractory Period IV Myelinated Axons V Synapses Outline of Current Lecture I Cessation of the Signal II Postsynaptic Potentials III Neuronal Circuits IV Autonomic Nervous System Visceral Motor Division Current Lecture I II Cessation of the Signal a How do we stop the signal i Diffusion neurotransmitters can leak out of the synapse because there are no walls to contain them ii Re uptake done by pre synaptic neuron 1 SSRI selective serotonin re uptake inhibitors inhibit re uptake neurotransmitter stays in synapse iii Degradation enzymes breakdown neurotransmitters 1 Acetylcholinesterase AChE breaks down ACh Postsynaptic Potentials a In postsynaptic cell i Depolarization EPSP excitatory can lead to action potential 1 2 Multiple EPSP s required to trigger action potential 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 3 ii Hyperpolarization IPSP inhibitory can negate effects of other neurons 1 Used if you want to prevent neurons from having action potentials III IV 2 Neuronal Circuits a Reverberating i Ex control of respiration b Diverging i Ex control of muscles c Converging i Ex sensory system take in information sent to the brain Autonomic Nervous System Visceral Motor Division a Responsible for i Changing physiology of body for the flight or fight response ii Returning it to state of rest digest iii Maintaining homeostasis temperature blood pressure blood pH ion balance b Poll Everywhere Which system does not contain visceral structures Skeletal c Somatic vs Visceral i Visceral cardiac and smooth muscle glands visceral targets ii Visceral neurons innervate smooth muscle glands even if they are found in the somatic part of the body d Visceral Reflexes Reflex Arc i ii Visceral effector autonomic nervous system iii Unconscious automatic stereotyped responses to stimulation iv Example blood pressure 1 Baroreceptor in carotid artery lead to the brain 2 If blood pressure is high a signal is sent along nerve glossopharyngeal sensory visceral and goes to the cardiac center 3 Vagus nerve transmits inhibitory signal to cardiac pacemaker 4 Example of negative feedback 5 e Neural Pathways i Somatic motor 1 All Myelinated goes to somatic effectors 2 ii Visceral motor 1 Myelinated preganglionic fiber goes to autonomic ganglion ACh 2 Unmyelinated postganglionic fiber visceral effectors a ACh parasympathetic b NE sympathetic 3 Heart gets innervation from both parasympathetic and sympathetic and can distinguish between the two 4 If heart has NE it is speeding up because that is used by the sympathetic division f 5 Sympathetic vs Parasympathetic Anatomy i Sympathetic 1 Short preganglionic neuron 2 Thoracolumbar origin 3 Innervates structures all over the body 4 Postganglionic neurons travel to innervate smooth muscle and glands in the skin 5 The adrenal medulla receives preganglionic neurons and itself acts as postganglionic neurons releasing NE to the blood 6 7 ii Parasympathetic 1 Long preganglionic neuron ganglion on visceral target 2 Craniosacral origin 3 Innervates structures all over the body 4 Cranial Nerves III VII IX X innervate visceral structures from the head to the abdomen 5 Pelvic Splanchnic Nerves S2 S4 innervate the large intestine rectum bladder reproductive organs 6