1 1 Lecture 05, 05 Sept 2006 Vertebrate Physiology ECOL 437 (MCB/VetSci 437) Univ. of Arizona, Fall 2006 Kevin Bonine & Kevin Oh 1. Nervous System and Neurons (Chap 10&11) http://eebweb.arizona.edu/eeb_course_websites.htm 5-2 Randall et al. 2002 (endocrine system later) 2 Wanted to give you a heads up for our next Doings on Sept 15th led by Doug Stuart (UofA, Regents' Professor Emeritus of Physiology ). Doug will be giving us an update of the Physiology seminar he gave at the end of last spring. Title: Historical reflections on the term "motor homunculus". Doings meets in 601 Gould-Simpson, 4:00-5:00.
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Lecture 05, 05 Sept 2006
Vertebrate PhysiologyECOL 437 (MCB/VetSci 437)
Univ. of Arizona, Fall 2006
Kevin Bonine & Kevin Oh
1. Nervous Systemand Neurons(Chap 10&11)
http://eebweb.arizona.edu/eeb_course_websites.htm
5-2 Randall et al. 2002
(endocrine system later)
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Wanted to give you a heads up for our next Doings on Sept 15th led by Doug Stuart (UofA, Regents' Professor Emeritus of Physiology ). Doug will be giving us an update of the Physiology seminar he gave at the end of last
spring.
Title: Historical reflections on the term "motor homunculus".
Doings meets in 601 Gould-Simpson, 4:00-5:00.
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Housekeeping, 05 September 2006
Upcoming Readings
today: Textbook, chapter 10 & 11
Wed 06 Sept: Tipsmark et al. 2002, bring problem set to doThurs 07 Sept: Textbook, chapter 10 &11Tues 12 Sept: Textbook chapter 11 & 12
Lab oral presentations 06 Sept9am – Nilam Patel2pm – Nick Brown
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Wed 06 Sept: Tipsmark et al. 2002
Kevin Oh will help with short glossary
Integrative
Good example of using multiple tools to addressinteresting physiological question
Filter the useful information from the unnecessary details
What other questions does this paper raise?
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Nervous System
- Neurons / Nerve Cells- Glial Cells (support)
- Signalling via combinationof Electrical and Chemical
- Integrate informationAFFERENT
Comprises
- Coordinate ResponseEFFERENT
5-2 Randall et al. 2002
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Organization of the Nervous System
Three main functions:1. Sensory Reception (converts environmental stimulus to elect/chem)
2. Central Processing3. Motor Output
Divided into CNS and PNSA. CNS = Central Nervous System
B. PNS = Peripheral Nervous System
- Brain and Spinal Cord(and eyes and interneurons)
- most sensory and motor axons
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7Hill et al. 2004, Fig 10.7
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Flow of Information
Very Simplee.g., Sensing Effectors
Simple Interneurons
Afferent Signal -> CNS -> Efferent Signal -> Response
Monosynaptic Polysynaptic
8-2 Randall et al. 2002
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Sensing Effectors
Sensors with Afferent and Efferent Properties/Homeostasis
Both function via reflex arcs, but often opposite effectsEfferent signal with two neurons:1. Preganglionic (NT released is Acetylcholine [Ach])
2. Postganglionic (PNS, receptor is nicotinic ACh)
Difference between Symp. and Para. is in:1. CNS origin2. Location of postganglionic somata3. Postganglionic NT 4. Receptors on target tissues
-Muscle reflexes in spinal cord, autonomic to brain
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Autonomic NS
2-Postganglionicsomata nearer CNSin chain ganglia
Sympathetic Parasympathetic2-Postganglionic
somata near effector,or in effector organ
3- Postganglionic NTis Norepinephrine
3- Postganglionic NTis ACh
4-Effector receptoris alpha or betaadrenergic
4-Effector receptor ismuscarinic ACh
Difference between Symp. and Para. is in:1. CNS origin2. Location of postganglionic somata3. Postganglionic NT 4. Receptors on target tissues
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27Hill et al. 2004, Fig 10.12
28Hill et al. 2004, Fig 10.13
Norepinephrine
Acetylcholine
Know a couple of examples:
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29Hill et al. 2004, Fig 10.13
Know a couple
of examples:
Norepinephrine
Acetylcholine
(chain ganglia)
30Hill et al. 2004
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“Squid axons are important to physiologists, and to the squid.”Hill et al. 2004, p.281
Sir Alan Hodgkin, Nobel Prize 1963
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Neurons:
Hill et al. 2004, Fig 11.1
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33Hill et al. 2004, Fig 11.2
1.PNS
2.CNS
3.Metabolic support
4.Phagocytes/immune
4 types of Glial Cells
Outnumber neurons 10:1 in mammalian brain
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Osmotic Properties of Cells and Relative Ion Concentrations
Na+Na+ K+K+
Cl-Cl-
4-12 Randall et al. 2002
Ca+
Ca+
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Movement Across Membranes
Electrochemical Gradient
Concentration gradient
Electrical gradient
Electrochemical equilibrium
Equilibrium potential (Ex in mV)
Na+Na+
--
--
-
-
-
-
-
-
-
++
+
+
+
+
+
+
++
++
K+K+
--
--
-
-
-
-
-
-
-
++
+
+
+
+
+
+
++
++
when [X] gradient = electrical gradient
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Equilibrium potential (Ex in mV)
“Every ion’s goal in life is to make the membrane potential equal its own equilibrium potential (Ex in mV)”
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To change Vm, A Small Number of Ions Actually MoveRelative to the Number Present both
Inside and Outside the cell
The concentration gradients are not abolishedWhen the channels for an ion species open
Gradients allow for ‘work’ to be done, e.g., action potential sends signal along axon
-Gradient established by pumps (ATP)
Membrane Potential
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Membrane Potential
- Driven by ions that are permeable to the membrane (and have different [ ]in as compared to [ ]out a.k.a. gradient created with ATP)
- emf determines which direction a given ion (X) will move when the membrane potential is known
- Equilibrium Potential (Ex in mV):~The equilibrium potentials of all the permeableions (a function of their established gradients) will determine the membrane potential of a cell
emfx = Vm - Ex
- K+ for example
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Membrane Potential
- Resting Membrane Potential driven by K+ efflux and,to a lesser extent, Na+ influx
- Na+/K+ ATPase pump generates gradients that, for these permeable ions, determinemembrane potential
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Osmotic Properties of Cells and Relative Ion Concentrations