10 14 14 Electrical Signals Ac on Poten al Propaga on Lesson 23 BIOL 1108 15 October 2014 1 Unit Animal Form and Func on Today s Topic Ac on Poten al Propaga on Today s learning objec ves Be able to describe how an electrical signal moves down an axon from one neuron to the next apply what you ve learned to real world situa ons 2 1 10 14 14 Figure 48 11 5 Key Na K 4 Falling phase of the action potential 3 Rising phase of the action potential Membrane potential mV 50 OUTSIDE OF CELL 100 Sodium channel Potassium channel 3 0 50 2 Depolarization Action potential Threshold 2 1 4 5 1 Resting potential Time INSIDE OF CELL Inactivation loop 1 Resting state 5 Undershoot 3 Channels in the cell membrane of an axon 4 2 10 14 14 t t 5 Ac on Poten al Propaga on Speed 1 2 6 3 10 14 14 Ac on Poten al Propaga on Speed Size and Structure Myelina1on Type Giant Squid Unmyelinated Mammals Unmyelinated Axon Diameter Up to 1 mm 2 m Mammals Myelinated 5 m Mammals Myelinated 20 m Speed Example 100m Propulsion sec 2m sec Warm temperature sensors 40m Pain mechano sec receptors 120m sec In 2m Tall Person NA Toe to brain in 1 sec Toe to brain in 50 ms Motorneurons Brain to to muscle toe in 16 ms 7 Channels in the cell membrane of an axon 8 4 10 14 14 Ac on Poten al Propaga on Speed Structure 9 In a neuron signal transmission speed is a ected MOST by which structure a dendrites b axon hillock c axon size d myelin sheath D SQUID drawing credit dolphin4life weebly com 10 5 10 14 14 Figure 48 4 Signal Movement Between Neurons Dendrites Stimulus Axon hillock Nucleus 1 synapses Cell body Presynaptic cell Signal direction Synapse Axon 2 synapses Synaptic terminals Synaptic terminals Postsynaptic cell Neurotransmitter 11 Figure 48 15 Presynaptic cell Neuron to Neuron Postsynaptic cell Axon Synaptic vesicle containing neurotransmitter 1 Communica on for Chemical Synapses Postsynaptic membrane Synaptic cleft Presynaptic membrane 3 K Ca2 2 Voltage gated Ca2 channel Ligand gated ion channels 4 Na 12 6 10 14 14 5 groups of Neurotransmiaers Acetylcholine muscle s mula on memory forma on learning Amino Acids long term memory Biogenic Amines sleep mood aaen on learning Used for nervous system disorders and treatments Neuropep1des pain recep on Gases Nitric oxide local regulators Carbon monoxide hypothalmic hormone release intes ne smooth muscle plasma membrane hyperpolariza on 13 Post Synap c Responses 0 55 70 0 Time Inhibitory Post Synap c Poten al IPSP Membrane poten al mV Membrane poten al mV Excitatory Post Synap c Poten al EPSP 0 55 70 0 Time How does the membrane poten al in the postsynap c neuron change with an EPSP vs an IPSP 14 7 10 14 14 Consider What happens when you have excitatory and inhibitory synapses ring simultaneously 15 Electrical signals are kept moving in one direc on down an axon by which of the following occurrences a potassium leaving the cell rapidly when voltage gated potassium channels are open b sodium entering rapidly when voltage gated sodium channels are open c sodium and potassium exchange through the sodium potassium pump d potassium owing through Ligand gated ion channels 16 8 10 14 14 Nervous System Disorders Schizophrenia distorted percep on of reality by fragmen ng brain func ons 1 of world s popula on Depression depressed mood abnormal sleep appe te and energy Major depression 1 in 7 adults Bipolar disorder 1 of world s popula on Drug Addic1on compulsive consump on and lack of intake control including alcohol and nico ne Alzheimer s Disease progressive mental deteriora on demen a confusion and memory loss No cure but some drugs relieve symptoms 10 of people age 65 35 of people age 85 Parkinson s Disease progressive motor disorder muscle tremors poor balance exed posture shu ing gait No cure but some drugs manage symptoms 1 of people age 65 5 of people age 85 17 Animal Form and Func on Ac on Poten al Propaga on Today s learning objec ves Be able to describe how an electrical signal moves down an axon If given the next slide could from one neuron to the next you describe these apply what you ve learned to real world situa ons Think about How does knowledge about electrical signals aid in trea ng nervous system disorders 18 9 10 14 14 How are ac on poten als propagated down the axon How does a signal move from one neuron to the next Axon Terminal 19 10