L7_NPB_101 - Lecture 7 •  SmartSite: –  Lecture...

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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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