Physiology 206 Lecture 5 Outline of Last Lecture I. NeuronsII. Glia cellsIII. Action potentialsIV. Voltage Gated Ion channelsOutline of Current Lecture I. AxonsII. Action potentialsIII. Myelin sheathIV. Neurotransmitters V. Presynaptic cells, postsynaptic cellsVI. Central nervous systemVII. Peripheral nervous systemCurrent Lecture1/24/14These 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.- Node of Ranvier: part of the axon that is directly exposed to ECF- Rate of Action Potentialso Travel faster with myelinated axons then non-myelinated axons Myelinated axons: 0.1 seconds for a message to travel from toes to spinal cord Non-myelinated axons: messages travel ~3 feet/secondo Axons with larger diameters transmit action potentials faster and axons with smaller diameters transmit action potentials slower- Salutatory conductiono Action potentials ‘jump’ from one nod to another- Myelin sheath limits interaction of axons with ECFo Prevents large concentration difference between the inside of the axon and ECFo Allows messages to travel down an axon more efficiently- Interneurons (CNS) are non-myelinatedo Have very small amount of space to transmit messages, don’t need speed of myelin sheath- Neurotransmitterso Most common is acetylcholine Stored in axon terminals in vesicles Ach crosses synapse Reached acetylcholine receptors on target cello Presynaptic cell sends the messageo Postsynaptic cell receives the message- Chemical synapse-uses Ach- Electrical synapseo Cells next to each other frequently have connections between the cytoplasm via gap junctions, allowing ions to pass througho These cells can pass messages to each othero Occurs in many tissues- In periphery, the target of the message can be muscle tissue or glands- Inhibited cellso It’s harder to fire action potentialso Usually because the distance of the synapse is too greato Ex: postsynaptic cell goes from -75mV to -80mV- Excitatory synapseo When presynaptic cell make postsynaptic cell more negative to make it closer to the thresholdo This way a weaker action potential is needed to send a messageo Ex: postsynaptic cell goes from -75mV to -65mV- Cells can be presynaptic to multiple postsynaptic cells: creates an extensive network- Central Nervous Systemo Braino Spinal Cord- Peripheral Nervous Systemo Autonomic: controls internal organs, involuntary actions (respiration, heart rate) Sympathetic Parasympathetico Somatic : controls skeletal/voluntary
View Full Document
Unlocking...