BCMB 230 1st Edition Lecture 10 Outline of Last Lecture I Review of Last Lecture II The Last Membrane Potential III Neurotransmitter Storage and Release Outline of Current Lecture I Classification of Neurotransmitters II Biogenic Amines III Drugs associated with Neurotransmitters IV Peripheral Nervous System Current Lecture I Classification of Neurotransmitters Acetylcholine ACh very common Biogenic amines neurotransmitters derived from an amino acid Catecholamines all made from the amino acid tyrosine Dopamine DA Norepinephrine NE Epinephrine Epi Serotonin 5 hydroxytryptamin 5 HT made from tyrptophan Histamine has different functions depending on where it is released from more likely to be a paracrine agent Amino Acids Excitatory amino acids ex glutamate Inhibitory amino acids ex gamma aminobutyric acid GABA and glycine amino acid not used for protein synthesis Neuropeptides varies in size ex endogenous opioids oxytocin tachykinins Gases ex nitric oxide carbon monoxide hydrogen sulfide nitric oxide functions within cardiovascular system as both a neurotransmitter and a paracrine agent Purines ex adenosine and ATP metabolic byproducts II Biogenic Amines 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 Acetylcholine made from choline and acetyl CoA can get rid of acetylcholine using an enzyme called acetylcholinesterase which limits how much it is going to react Two classes of receptors that bind to acetylcholine cholinergic receptors Can be divided into two kinds nicotinic receptors ligand gated channels a Na and K channel that causes depolarization tends to be excitatory muscarinic receptors signal transduction mediated by a G protein can activate multiple types can cause depolarization or hyperpolarization can be excitatory or inhibitory Catecholamine all made from amino acid tyrosine tyrosine intermediate dopamine norepinephrine epinephrine norepinephrine and epinephrine have similar structures so will bind to same enzyme when neurotransmitters more norepinephrine than epinephrine when hormones more epinephrine than rnorepinephrine Monoamineoxidase is the enzyme that breaks down catecholamine into epinephrine and norepinephrine and to a smaller extent serotonin Adrenergic receptors alpha uses a variety of G proteins uses a variety of second messengers can be excitatory or inhibitory beta uses G proteins but then uses cyclic AMP as a second messenger Seratonin largely controlled by a re uptake transporter class of drugs called SSRI selective serotonin reuptake inhibitors increase level or production of serotonin because it is not being broken down III Drugs Associated with Neurotransmitters Agonist binds to a receptor and mimics the action of a neurotransmitter initiating signal transduction Antagonist binds to a receptor but does not initiate signal transduction blocks neurotransmitters from binding drugs can influence enzymes or proteins to increase degradation or removal of neurotransmitters Epinephrine and norepineprhine correct levels of norepinephrine and serotonin cause a good mood some drugs are used to level out if there is an imbalance increase levels of norepinephrine and serotonin by blocking enzymes and transporters monoamineoxidase inhibitors MAOIs stops breakdown of norepinephrine sometimes serotonin causes an elevation of mood selective serotonin reuptake inhibitors SSRIs stop reuptake of serotonin neurotransmitters are very much involved in the sympathetic nervous system and can be increased by exercise to increase serotonin without drugs eat foods with tryptophan an amino acid that is largely dietary IV Peripheral Nervous System Somatic Motor skeletal muscle control excitatory all or none have a single cell a single neuron one fiber path that comes from the muscle and goes to the CNS neurons release ACh which goes to the skeletal muscle effector which has a nicotinic receptor on it Visceral Motor Autonomic smooth cardiac muscle or glands excitatory or inhibitory on different cells graded response two fiber two neuron path in PNS have a preganglionic fiber and postganglionic fiber CNS to ganglion that synapses to two neurons fibers pre and post which then leads to the smooth or cardiac muscles glands or other cells synapse is in the ganglion sympathetic and parasympathetic sympathetic gets body ready for something fight or flight in the vicera and face but also the skin and blood vessels throughout the body blood vessels out in skeletal muscle ganglia close to CNS distribution system allows for sympathetic nerves originating in the thoracic lumbar sections of the spinal cord to go anywhere in the body parasympathetic does opposite rest digest largely in the vicera gut and the face where the effectors are glanglion close to effector distribution system is cranial sacral if one is the accelerated the other is going to be the brake preganglionic autonomic fibers release acetylcholine postganglionic autonomic fibers have nicotinic receptors on dendrites parasympathetic postganglionic fibers release AcH parasympathetic effectors have mascrine receptors sympathetic postganglionic fibers release norepinephrine sympathetic effectors have alpha or beta adrenergic receptors Pathways of nerve controls vagus nerve cranial nerve X comes out of the brain and goes to the vicera phrenic nerve comes from the neck and goes to the diaphragm somatic motor phrenic nerve controls diaphragm sympathetic trunk distribution system that allows us to get sympathetic nerves anywhere