L7_NPB_101 - Lecture 7 SmartSite Lecture 7 Notes...

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Unformatted text preview: Lecture 7 SmartSite: Lecture 7 Notes Announcements: None Review Synapse Organiza;on of the Nervous System Sensory Systems Reading (Recommended): Reading: Relevant por;ons of Chapters 5 & 6 1 REV: Synapse Physiology Transform presynap;c AP into postsynap;c Em change. 1) 2) 3) 4) 5) 6) 7) 8) Axon AP depolarizes Axon terminal. Increase Ca+2 Axon terminal permeability. Release chemical NeurotransmiRer. Diffusion of NT across synap;c cleV. NT binds to receptors in postsynap;c membrane. Postsynap;c response. 2 basic types of response EPSP & IPSP. Removal of NT from synap;c cleV. 2 REV: Membrane Physiology Neuronal events are mediated by controlled changes in permeability of ion conductance across cell membrane. Membrane is a lipid bi-layer with numerous elements imbedded in it. We have discussed trans-membrane elements which allow movement of ions, including: Ion channels for different ions or groups of ions Ion channels have different levels of permeability control Open (leaks) Gated (controlled permeability) Voltage-gated Chemically-gated Gated channels have different s;muli, including: Ac;ve transport mechanisms also facilitate movement of ions, normally against concentra;on gradient. Membrane has a voltage poten;al across it (RMP) due to ion Na+ and K+ channel leaks and a Na+/K+ ATPase electrogenic pump. Neuronal AP results from s;mula;on of Voltage-gated Na and K channels. Synap;c poten;al results from AP s;mula;on of Voltage-gated Ca channels, which leads to NT release which s;mulate Chemically-gated channels (Na+/K+; K+; or Cl-). 3 Nervous System 4 Func;ons of the Nervous System Input (Afferent) Transduce informa;on (convert s;muli into electrical signal) Integra;on Communica;on (transfer informa;on) Processing and integra;on of signals Output (Efferent) Genera;on of responses and control of ac;vi;es Homeosta;c Regula;on Higher cogni;ve func;on Motor control 5 Nervous System Organiza;on 2 Cell types Neurons (func;onal; 1012) & Glia (support) 2 Primary divisions Central nervous system (CNS) Consists of brain and spinal cord Peripheral nervous system (PNS) Afferent division (Input) Carries informa;on to the CNS Efferent division (Output) Carries informa;on away from CNS to effector organs (muscles and glands) Divided into Soma;c nervous system Autonomic nervous system 6 Nervous System Organiza;on OUTPUT (Efferent) INPUT (Afferent) Fig. 5-1, pg. 134 7 The Central Nervous System (CNS) & (some) Cor;cal Func;ons TOP (DORSAL) Motor Sensory Personality FRONT (ROSTRAL) Speech Hearing EmoGon Autonomic RegulaGon Fig. 5-8, pg. 146 (See also Fig. 5-9a, pg. 147) Vision BACK (CAUDAL) LocomoGon BOTTOM (VENTRAL) 8 The CNS (Midline SagiRal View) Table 5-2, pg. 144 (see also Fig. 5-15, pg. 155) 9 The Brain (Coronal View) Fig. 5-14a, pg. 154 10 Humans Have 31 Pairs of Spinal Nerves Fig. 5-25, pg. 173 11 Organiza;on of Spinal Nerves Fig. 5-26, pg. 174 12 Transverse Sec;on of the Spinal Cord Gray MaJer TOP (DORSAL) White MaJer INPUT OUTPUT BOTTOM (VENTRAL) Fig. 5-29, pg. 176 13 "Nothing is in the mind that does not pass through the senses" Aristotle Sensory Systems "Sensa'on is an abstrac'on, not a replica'on of the real world" Vernon Mountcastle 14 Percep;on Conscious interpreta;on of external world derived from sensory input Sensory input does not give true reality percep;on. Why? We don't perceive or encode everything Humans have receptors that detect only a limited number of exis;ng energy forms Informa;on channels in our brains are not high- fidelity recorders Cerebral cortex further manipulates the data 15 Can't transduce all levels of energy TransducGon in not linear (1:1) Sensa;on is an Abstrac;on of Reality Threshold Response SaturaGon SGmulus 16 CNS Manipula;on: What You Perceive? Fig. 6-8 & 6-9, pg. 191 17 Func;onal Classes of Neurons Afferent neurons (Receptors; Input) Interneurons (99% of neurons; Processing) Found en;rely within CNS Responsible for Inform CNS about condi;ons in both the external and internal environment Efferent neurons (Output) Integra;ng afferent informa;on and formula;ng an efferent response Higher mental func;ons associated with the "mind" Carry instruc;ons from CNS to effector organs muscles and glands 18 Func;onal Classes of Neurons INPUT OUTPUT Fig. 5-2, pg. 135 (see also Fig. 6-2, pg. 185) 19 ...
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