BIOL 460 1nd Edition Exam 2 Study Guide Lectures 1 9 Possible Essay Questions 1 How do monoamine neurotransmitters function question from last exam The monoamine neurotransmitters function via either the andenylate cyclase cAMP signal transduction pathway dopamine serotonin A2 B1 B2 adrenergic receptors Figure 7 31 Monoamine bonds to receptor G protein is used as second messenger alpha subunit turns on andenylate cyclase converting STP to cyclic adenosine monophosphate cAMP and pyrophosphate cAMP is a very common 2nd messenger system cAMP activate protein kinase add phosphate to a protein phosphorylates protein alters protein conformation makes protein active can turn on ion channels or enzyme 2 Nitric oxide as neurotransmitter and the action of Viagra Figure 20 22 Nitric oxide NO is a gaseous neurotransmitter It is produced when a calcium voltage gated channel on a pre synaptic is opened and nitric oxide synthetase is turned on this causes the production of nitric oxide from L argenine The NO can diffuse through the plasma membrane of the terminal bouton through the synaptic cleft and directly into the visceral effector organ in this example the vascular smooth muscle in the penis There it turns on guanylate cyclase Guanylate cyclase hydrolyzes guanosine triphosphate into cyclic guanasine monophosphate cGMP and pyrophosphate The cGMP then blocks calcium ligand gated channels on the post synaptic cell which prevents muscle contraction This relaxation of muscles causes vasodilation The vasodilation causes the erection This system is turned off through the breakdown of cGMP by phosphodiesterase The drug Viagra inhibits phosphodiesterase Therefore there is no breakdown of cGMP no opening of calcium ligand gated channels and a continuous muscle relaxation Therefore an erection is maintained for a longer period of time 3 Structure of parasympathetic division of the autonomic nervous system The parasympathetic division of the autonomic nervous system is structured as a twoneuron pathway The pre ganglionic neurons are very long and synapse with terminal ganglia very near or inside the effector organs The post ganglionic neurons are very short and cause the physiological effects The nerves involved in this system are the cranial nerves and the sacral segments 2 4 The main nerve is the vagus nerve cranial nerve X This innervates all of the parasympathetic nervous system except the urinary system and the reproductive system 4 Structure of sympathetic division of the autonomic nervous system The sympathetic division of the ANS is composed of the segments T1 L2 This division causes what is known as the flight or fight response The sympathetic division is a two neuron system First the sympathetic pre ganglionic neuron exits the spinal column with the cell body in the CNS through the ventral root and enters the spinal nerve proper with the axon being termed a white ramus communicantes because it is myelinated There it can do one of three things First the pre ganglionic neurons below the diaphragm can bypass what is known as the chain ganglia and continue on as a splanchnic nerve It will synapse with a collateral ganglion either the celiac superior mesenteric or inferior mesenteric The post synaptic neuron will innervate organs such as the stomach urinary system and reproductive system Second the pre ganglionic neuron can synapse with a ganglion in the chain ganglia The chain ganglia are a series of ganglia that run parallel to the spinal column The pre ganglionic neuron can synapse directly with a ganglion in the chain ganglia which will then send unmyelinated axons grey rami communicantes to the effector organs in this case arrector pili muscles glands in the skin and visceral smooth muscle in the somatic part of the body Finally the pre ganglionic neuron can move up or down the chain ganglia and then synapse with any of the ganglia present 5 Adenylate cyclase cAMP 2nd messenger system This system is one of the many systems that polar hormones can activate First the ligand a hormone or neurotransmitter such as norepinephrine binds to the receptor protein This causes activation of a G protein complex The G protein complex separates and one subunit turns on adenylate cyclase Adenylate cyclase breaks down adenosine triphosphate into cyclic adenosine monophosphate cAMP and pyrophosphate PO4 PO4 cAMP activates protein kinases which phosphorylate proteins This changes the conformation of the protein typically activating it The protein is often an enzyme or channel and this causes a physiological response The system is turned off in several ways First the g protein turns itself off cAMP is broken down by phosphodiesterase The ligand is destroyed Adenylate cyclase turns itself off The protein kinases effects are reversed by protein phosphatases 6 Phospholipase C Ca 2nd messenger system This is one of three systems that polar hormones can cause a physiological response First a ligand binds to a receptor protein This turns on a g protein complex The gprotein complex separates and one subunit turns on phospholipase C Phospholipase C breaks down a phospholipid into diacyl glyceride which remains in the plasma membrane and inositol triphosphate IP3 IP3 diffuses through the cytoplasm to the rough ER where it causes a release of calcium which is built up in the ER via a pump The calcium release causes the binding of Ca2 to calmodulin The Ca2 Calmodulin complex then turns on protein kinases causing a physiological effect Turning off this system requires several steps First the ligand is released or destroyed The g protein complex turns itself off The calcium is pumped back into the rough ER IP3 is broken down Finally protein phosphatases reverse the effects of protein kinases 7 Tyrosine kinase 2nd messenger system In the tyrosine kinase signal transduction pathway a hormone usually a growth hormone binds to the two tyrosine kinase monomers This turns on the two monomers to phosphorylate the tyrosine resides on each other Then the active dimer can phosphorylate the tyrosine residues of second messengers using phosphates from ATP This causes the physiological effect 8 Mechanism of steroid H family action Steroid hormones are transported using carrier proteins in the blood this is a transitory association and the hormones can break off When the hormones reach the target cell they enter the cell and bind with the ligand binding domain of a nuclear receptor protein NRP The hormone NRP enters the nucleus and