Survey to Human Anatomy and Physiology Lecture Notes EXAM 2 Lectures 6 and 7 Components of nervous system intro to neurophysiology Communication the key Vision movement many diff systems rely on nervous system for integration Master switch HQ main circuit breaker of the entire organism Integrates all systems together as well as maintaining sensory system for our homeostasis model Nervous System structure One major division point of the nervous system Central nervous system vs peripheral nervous system CNS brain and spinal cord PNS cranial nerves from brain and spinal nerves from spinal cord CNS vs PNS CNS large structures PNS smaller in size larger area Interstate vs highways routes Entire nervous system composed of neurons functional unit of nervous system Neurons functional and structural Produce conduct electrochemical impulses Neurons functional Neurons that originate within the brain and spinal cord and carry messages to certain targets Efferent motor neurons carry message out of CNS to diff targets Afferent sensory neurons carry message into CNS Motor efferent Activates 2 separate divisions Autonomic nervous system ANS Somatic nervous system ANS controls cardiac glands and smooth muscle contraction involuntary Sympathetic readies body for quick action fight or flight arousal Parasympathetic conserves energy calming resting sleeping is ultimate state Somatic voluntary CNS to skeletal muscles NMJ neural molecular junction A nerve Not a neuron is many neurons thousands or hundreds of thousands of neurons Nerves need support Supporting cells that assist neurons 6 types 1 Astrocytes help regulate external environment in CNS 2 Microglia remove foreign dead material from CNS 3 Ependymal cell line ventricles of brain and spinal cord produce CSF cerebra spinal fluid 4 Oligodendrocytes myelin sheaths around axon within CNS 5 Satellite cells surround ganglia grouping of nerves in PNS function not clear physically support ganglia in PNS 6 Schwann cells myelin sheath around axons in periphery Support Myelin Myelin sheath what is it A layer of fat lipids around axons in both CNS and PNS Functions 1 Protect nerve fibers 2 insulates axons form each other 3 Increases speed of electrical transmission of nerve impulses Schwann cells and oligodendrocytes create the fat or myelin Lack of myelin slower transmission of impulse MS multiple sclerosis Degenerative disease within the CNS that destroys myelin around axons Leads to scars skleros that prevent normal transmission of impulse Impulse from form comes function Structures of neurons Cell body nucleus and control center of nerve cell Dendrites branch like extensions at end of neuron allows for multiple connections to other neurons in CNS and muscle in PNS Axon each neuron has a single axon where impulse travels various length depending on tissue As the end of EACH axon are axon terminals where message is either continued or discontinued Axon terminals make connection with next neuron neurotransmitters Axon is how and why neural message travels from one place to another Modifications on axon Nodes of Ranvier spaces between myelin sheath along axon Axon is exposed has to be so that electrical message can travel down axon Impulse Myelin increases transmission Nodes spaces along axon where transmission occurs Myelin prevents message from conduction all along axon Rather message skips or jumps from node to node salutatory conduction Salutatory conduction allows for faster transmission versus unmyelinated axons Action potential electrical message that travels down an axon in the form of an action potential Major players axon membrane Na K myelin Resting membrane potential now must be DEPOLARIZED Action Potential Primary basis of AP is based upon axon permeability to Na and K This permeability other than normal concentration gradient is regulated by respective gates Na gate K gate In response to stimulation gates open Basic scheme Na enters axon FIRST then K moves out of axon This flow of ions and change in membrane potential ACTION POTENTIAL Stepwise process steps 1 4 ionic state and electrical state need to know for test 1 Resting state resting membrane potential K high inside Na high out CHANNELS all channels closed RMP 70 mV 2 Reversal of membrane potential DEPOLARIZATION Local current depolarizes membrane allowing Na channels to open Na rushes in down concentration gradient K channels still closed Membrane potential is now going from 70 mV to a more positive value 30mV 3 Na channels close K channels open K leaves axon returning cell towards original value to 70 mV REPOLARIZATION down concentration gradient Returning cell to original potential is necessary for another AP to occur 4 Undershoot of hyperpolarization K permeability is prolonged due to K channels remaining open Repolarization brings cell back to original electrical situation as step 1 but not ionic situation what brings ions back to original status Na K pump 3 Na out 2K in Propagation AP at one portion of membrane needs to continue on down axon How Propagation The previous region of the axon that has just been depolarized is currently hyperpolarized and under a period where it cannot regenerate an AP Therefore if region previous cannot be depolarized only region that is currently at rest can be depolarized Toothpaste tube squeeze from bottom Water hose or straw Same principal of axon propagation AP propagation synapse Saltatory conduction at Nodes allows for message to quicly propagate down axon Na channels ae actually concentrates at Nosed of Ranvier K along axon Message reaches end synapse Continuation of message Individual assignment Investigate learn something about research 1 neurotransmitter Serotonin dopamine etc 1 page typed paper Lectures 8 and 9 Synapse Junction between two neurons First seen with NMJ Continuation or discontinuation of original message Procedural message from continuation of Na K influx efflux all the way to end of axon Axon terminal end of axon Pre synaptic and post synaptic neuron O Which is which Within axon terminals are synaptic vesicles Within these vesicles are neurotransmitters NT Neurotransmitters act to propagate or end the original message sent from the presynaptic terminal Vesicle contain NT from presynaptic terminal is regulated by and external ion Ca2 controls vesicle and NT release Neurotransmitters NT Ach acetylcholine excitatory and inhibitory NMJ and ANS synapses Alzheimer s is associated with a decrease in Ach secreting neurons NE