Synapses A. Neuromuscular Junction (typical ACh synapse) 1. arrival of action potential at terminal bulb triggers opening of voltage-gated Ca ++ channels.

Slides:

Advertisements

Similar presentations

Advertisements

Neural Signaling: Postsynaptic Potentials Lesson 9.

Mean = 75.1 sd = 12.4 range =

Neurotransmitter Release Signal Received (EPSP/IPSP)

LECTURE 9: INTEGRATION OF SYNAPTIC INPUTS (Ionotropic Receptors) REQUIRED READING: Kandel text, Chapter 12 At neuromuscular synapse, single axonal action.

Computer Simulation of Neurophysiology Presented in Lab.

NEUROMUSCULAR JUNCTION DR. ZAHOOR ALI SHAIKH LECTURE

Chemical synapses: post-synaptic mechanisms. Postsynaptic Membranes and ion channels Ligand gated ion channels – a review a. Resting K + channels: responsible.

Neurotransmitters A. Criteria

Gated Ion Channels A. Voltage-gated Na + channels 5. generation of AP dependent only on Na + repolarization is required before another AP can occur K +

‘YOU’ You are ‘YOU’ because of your NERVOUS SYSTEM kidneyHeart NERVOUS SYSTEM, not because of your kidney or Heart or……………… HUMAN NERVOUS SYSTEM HUMAN.

Figure 11.3 Neuroglia. © 2014 Pearson Education, Inc. Capillary Neuron

Transmission across synapses a. Depolarization of presynaptic cell b. Increase in inward gCa ++ via voltage gated Ca ++ channels c. Vesicle migration.

Lecture 4- Action Potential propagation and synaptic transmission ©Dr Bill Phillips 2002, Dept of Physiology Continuous Propagation of action potentials.

NERVOUS TISSUE.

Effects of Excitatory and Inhibitory Potentials on Action Potentials Amelia Lindgren.

Inhibitory and Excitatory Signals

Chapter 8c Neurons: Cellular and Network Properties.

Communication between neurons

PHYSIOLOGY 1 LECTURE 14 SYNAPTIC TRANSMISSION. n Objectives: The student should know –1. The types of synapses, electrical and chemical –2. The structure.

Two types of signal conduction within a single neuron

Action Potentials and Conduction. Neuron F8-2 Axons carry information from the cell body to the axon terminals. Axon terminals communicate with their.

Ch. 12 Nervous Tissue. Objectives Understand how the nervous system is divided and the types of cells that are found in nervous tissue Know the anatomy.

Announcements Tutorial next Thursday, Oct 9 –Submit questions to me Mid-term schedule Go vote!

David Sadava H. Craig Heller Gordon H. Orians William K. Purves David M. Hillis Biologia.blu C – Il corpo umano Neurons and Nervous Tissue.

Neurons The two principal cell types of the nervous system are:

1 Neuron structure fig Myelin sheath fig 6-2a Peripheral nervous system: Schwann cells Central nervous system: oligodendrocytes.

Essential knowledge 3.E.2 Animals have nervous systems that detect external and internal signals, transmit and integrate information, and produce responses.

Chapter 48 Neurons, Synapses, and Signaling. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Overview: Lines of Communication.

The Nervous System Components Brain, spinal cord, nerves, sensory receptors Responsible for Sensory perceptions, mental activities, stimulating muscle.

Using your textbook, (page ) find and define the following terms: Action potential Polarized membrane Depolarization, repolarization Sodium-potassium.

Copyright © 2010 Pearson Education, Inc. The Synapse A junction that mediates information transfer from one neuron: To another neuron, or To an effector.

Physiology of synapses, interneuronal connections

SYNAPTIC & NEUROMUSCULAR TRANSMISSION Ass. Prof. Dr. Emre Hamurtekin EMU Faculty of Pharmacy.

Synaptic Transmission Classical –Mediated by Neurotransmitter Gated Ion Channel aka ionotropic receptors Neuromodulatory –Mediated by Metabotropic Receptors.

Now we know how synapses work Next: - integration of synaptic excitation and inhibition - synaptic plasticity - diseases of neuromuscular transmission.

Neuron Synapses I.Anatomy of the Synapse II.Chemical Synapse III.EPSP & IPSP IV.Neurotransmitters.

Action Potential: Resting State Leakage accounts for small movements of Na + and K + Each Na + channel has two voltage-regulated gates.

How neurons communicate ACTION POTENTIALS Researchers have used the axons of squids to study action potentials The axons are large (~1mm) and extend the.

Neurons & Nervous Systems. nervous systems connect distant parts of organisms; vary in complexity Figure 44.1.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ch 48 – Neurons, Synapses, and Signaling Neurons transfer information.

Action Potential (L4).

Neurons, Synapses, and Signaling

Nucleus Dendrites Collect electrical signals Cell body Integrates incoming signals and generates outgoing signal to axon Axon Passes electrical signals.

Neural Communication: Action Potential Lesson 10.

Announcements Midterm –Saturday, October 23, 4:30pm Office Hours cancelled today.

Electrochemical Impulses

What you should know The parts of the nerve What an action potential is How nerve cells are insulated and the function of this How nerve cells communicate.

University of Jordan1 Physiology of Synapses in the CNS- L4 Faisal I. Mohammed, MD, PhD.

Neural Communication Signaling within a neuron. Postsynaptic Potentials n E m changes dendrites & soma n Excitatory: + n Inhibitory: - ~

Chapter 2 Structure and functions of cells of the nervous system.

Nerves & signaling Ch 37. I. Nerves =  A. Cells called neurons bundled together in a sheath of connective tissue.

Electrical Properties of the Nervous System Lundy-Ekman, Chapter 2 D. Allen, Ph.D.

The Synapse A synapse is the functional connection between a neuron and a second cell. The second cell is also a neuron in CNS. In the PNS, the second.

 Chapter 48 Gaby Gonzalez Joyce Kim Stephanie Kim.

Chemical synapses: post-synaptic mechanisms

Chapter 48: Nervous System

What happens when action potential reaches axon terminal?

NOTES - UNIT 5 part 2: Action Potential: Conducting an Impulse

Action Potentials and Conduction

The Control Systems of the Body

At resting potential Most voltage-gated Na+ and K+ channels are closed, but some K+ channels (not voltage-gated) are open.

Cell Communication: Neuron.

A junction that mediates information transfer from one neuron:

Unit 5, Part 2 Notes – The Nervous System

Neural Signaling: Postsynaptic Potentials

Nervous system.

Functional Anatomy Excitatory Synapses Inhibitory Synapses

Neural Communication: Action Potential

Synaptic Transmission and Integration

Presentation transcript:

Synapses A. Neuromuscular Junction (typical ACh synapse) 1. arrival of action potential at terminal bulb triggers opening of voltage-gated Ca ++ channels

Synapses 2. Ca ++ influx  phosphorylation a. vesicle liberated from presynaptic actin network b. vesicle binds to presynaptic membrane

Synapses examples of phosphorylated proteins: N-ethylmaleimide- sensitive fusion protein (NSF)

Synapses soluble NSF attachment proteins (SNAPs) SNAP receptors (SNAREs)

Synapses vesicle recycled via endocytosis

Synapses some neurotransmitter leaks out of cleft some inactivated (acetylcholinesterase)

Neuromuscular Junction remainder binds to postsynaptic receptor on motor end plate each vesicle contains enough ACh to trigger miniature end- plate potential (mepp)

Neuromuscular Junction mepps can sum to generate end-plate potential (epp) epps can sum to threshold to generate action potential adjacent to the motor end plate

Neuromuscular Junction Disorders Curare binds to AChR paralysis

Neuromuscular Junction Disorders Botulinum toxin prevents release of ACh paralysis cleaves SNARE proteins

Neuromuscular Junction Disorders Myasthenia gravis antibody generated against AChR weakness worsens progressively

Neuromuscular Junction Disorders Neuromyotonia antibody generated against presynaptic K + channels axon terminal constantly depolarized (cramping)

Potential Transmission A. Electrotonic 1. graded 2. receptor (generator) potentials

Potential Transmission a.  stimulus, then  ∆ V m b. electrical signal spreads from source of stimulus c. problem: no voltage-gated channels here d. signal decay “passive electrotonic transmission”

Potential Transmission A. Electrotonic 3. good for only short distances 4. might reach axon hillock - that’s where voltage-gated channels are - where action potentials may be triggered

Potential Transmission B. Action potential 1. propagation without decrement 2. to axon terminal

Synaptic Transmission C. Alternation of graded and action potentials

Intraneuron Transmission A. All neurons have electrotonic conduction (passive) B. Cable properties 1. determine conduction down the axon process 2. some cytoplasmic resistance to longitudinal flow 3. high resistance of membrane to current “but membrane is leaky”

Intraneuron Transmission C. Propagation of action potentials 1. ∆ V m much larger than threshold - safety factor

Intraneuron Transmission C. Propagation of action potentials 2. spreads to nearby areas - depends on cable properties - inactive membrane depolarized by electrotonically conducted current

Intraneuron Transmission C. Propagation of action potentials - K + efflux behind region of Na + influx

Intraneuron Transmission C. Propagation of action potentials 3. unidirectional a. refractory period b. K + channels still open

Intraneuron Transmission C. Propagation of action potentials 4. speed a. relates to axon diameter and presence of myelin b.  axon diameter,  speed of conduction

Intraneuron Transmission D. Saltatory conduction 1. myelination a.  R m,  C m b. the more layering, the greater the resistance between ICF and ECF

Intraneuron Transmission D. Saltatory conduction c. charge flows more easily down the axon than across the membrane

Intraneuron Transmission D. Saltatory conduction 2. nodes of Ranvier a. internodes (between Schwann cells or oligodendrocytes) b. only exit for current c. only location along axon where APs are generated

Neuronal Integration A. Motor neurons as example 1. thousands of excitatory and inhibitory terminals on dendrites and soma - density often highest around hillock - proximity often confers preference

Neuronal Integration A. Motor neurons as example 2. control frequency of firing of motor neuron - only excitatory stimuli can cause behavior change

Neuronal Integration A. Motor neurons as example 3. these terminals are weak - multiple stimuli needed to trigger AP - prevents spontaneous activation of motor neurons

Neuronal Integration B. Spatial summation 1. inputs from several synapses summed to simultaneously change V m 2. often a battle between EPSPs and IPSPs

Neuronal Integration C. Temporal summation 1. second potential follows close after first 2. “piggybacks” 3. amplifies potential 4. spatial and temporal often together