Ch7bppt nerve impulses and reflexes

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Ch7bppt nerve impulses and reflexes

  1. 1. PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College The Nervous System 7 PART B Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  2. 2. Functional Properties of Neurons  Irritability  Ability to respond to stimuli  Conductivity  Ability to transmit an impulse Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  3. 3. Nerve Impulses  Resting neuron  The plasma membrane at rest is polarized  Fewer positive ions are inside the cell than outside the cell  Depolarization  A stimulus depolarizes the neuron’s membrane  A depolarized membrane allows sodium (Na+) to flow inside the membrane  The exchange of ions initiates an action potential in the neuron Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  4. 4. Nerve Impulses Figure 7.9a–b Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  5. 5. Nerve Impulses  Action potential  If the action potential (nerve impulse) starts, it is propagated over the entire axon (all or none)  Impulses travel faster when fibers have a myelin sheath Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  6. 6. Nerve Impulses Figure 7.9c–d Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  7. 7. Nerve Impulses  Repolarization  Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane  The sodium-potassium pump, using ATP, restores the original configuration Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  8. 8. Nerve Impulses Figure 7.9e–f Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  9. 9. Transmission of a Signal at Synapses  Impulses are able to cross the synapse to another nerve  Neurotransmitter is released from a nerve’s axon terminal  The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter  An action potential is started in the dendrite Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  10. 10. Transmission of a Signal at Synapses Axon of transmitting neuron Axon terminal Action potential arrives Vesicles Synaptic cleft Receiving neuron Synapse Figure 7.10, step 1 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  11. 11. Transmission of a Signal at Synapses Axon of transmitting neuron Axon terminal Action potential arrives Vesicles Synaptic cleft Receiving neuron Synapse Transmitting neuron Vesicle fuses with plasma membrane Synaptic cleft Ion channels Receiving neuron Figure 7.10, step 2 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  12. 12. Transmission of a Signal at Synapses Axon of transmitting neuron Axon terminal Action potential arrives Vesicles Synaptic cleft Receiving neuron Synapse Transmitting neuron Vesicle fuses with plasma membrane Synaptic cleft Ion channels Neurotransmitter is released into synaptic cleft Neurotransmitter molecules Receiving neuron Figure 7.10, step 3 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  13. 13. Transmission of a Signal at Synapses Axon of transmitting neuron Axon terminal Action potential arrives Vesicles Synaptic cleft Receiving neuron Transmitting neuron Vesicle fuses with plasma membrane Synaptic cleft Ion channels Neurotransmitter is released into synaptic cleft Synapse Neurotransmitter binds to receptor on receiving neuron’s membrane Neurotransmitter molecules Receiving neuron Figure 7.10, step 4 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  14. 14. Transmission of a Signal at Synapses Axon of transmitting neuron Axon terminal Action potential arrives Vesicles Synaptic cleft Receiving neuron Transmitting neuron Vesicle fuses with plasma membrane Neurotransmitter is released into synaptic cleft Neurotransmitter binds to receptor on receiving neuron’s membrane Neurotransmitter molecules Synaptic cleft Ion channels Synapse Receiving neuron Neurotransmitter Receptor Na+ Ion channel opens Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 7.10, step 5
  15. 15. Transmission of a Signal at Synapses Axon of transmitting neuron Axon terminal Action potential arrives Vesicles Synaptic cleft Receiving neuron Transmitting neuron Vesicle fuses with plasma membrane Neurotransmitter is released into synaptic cleft Neurotransmitter binds to receptor on receiving neuron’s membrane Neurotransmitter molecules Synaptic cleft Ion channels Synapse Receiving neuron Neurotransmitter Receptor Na+ Ion channel opens Neurotransmitter broken down and released Na+ Ion channel closes Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 7.10, step 6
  16. 16. Transmission of a Signal at Synapses Axon terminal Axon of transmitting neuron Action potential arrives Vesicles Synaptic cleft Receiving neuron Synapse Transmitting neuron Vesicle fuses with plasma membrane Neurotransmitter is released into synaptic cleft Neurotransmitter molecules Synaptic cleft Ion channels Neurotransmitter binds to receptor on receiving neuron’s membrane Receiving neuron Neurotransmitter Receptor Na+ Ion channel opens Neurotransmitter broken down and released Na+ Ion channel closes Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 7.10, step 7
  17. 17. The Reflex Arc  Reflex—rapid, predictable, and involuntary response to a stimulus  Occurs over pathways called reflex arcs  Reflex arc—direct route from a sensory neuron, to an interneuron, to an effector Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  18. 18. The Reflex Arc Skin Spinal cord (in cross section) Stimulus at distal end of neuron Sensory neuron Receptor Motor neuron (a) Effector Integration center Interneuron Figure 7.11a Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  19. 19. Simple Reflex Arc Sensory receptors (stretch receptors in the quadriceps muscle) Spinal cord (b) Figure 7.11b, step 1 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  20. 20. Simple Reflex Arc Sensory receptors (stretch receptors in the quadriceps muscle) Sensory (afferent) neuron Spinal cord (b) Figure 7.11b, step 2 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  21. 21. Simple Reflex Arc Sensory receptors (stretch receptors in the quadriceps muscle) Sensory (afferent) neuron Spinal cord Synapse in ventral horn gray matter (b) Figure 7.11b, step 3 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  22. 22. Simple Reflex Arc Sensory receptors (stretch receptors in the quadriceps muscle) Sensory (afferent) neuron Spinal cord Synapse in ventral horn gray matter Motor (efferent) neuron (b) Figure 7.11b, step 4 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  23. 23. Simple Reflex Arc Sensory receptors (stretch receptors in the quadriceps muscle) Sensory (afferent) neuron Spinal cord Synapse in ventral horn gray matter (b) Motor (efferent) neuron Effector (quadriceps muscle of thigh) Figure 7.11b, step 5 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  24. 24. Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord (c) Figure 7.11c, step 1 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  25. 25. Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord Sensory (afferent) neuron (c) Figure 7.11c, step 2 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  26. 26. Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord Sensory (afferent) neuron Interneuron (c) Figure 7.11c, step 3 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  27. 27. Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord Sensory (afferent) neuron Interneuron Motor (efferent) neuron (c) Figure 7.11c, step 4a Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  28. 28. Simple Reflex Arc Sensory receptors (pain receptors in the skin) Spinal cord Sensory (afferent) neuron Interneuron Motor (efferent) neuron Effector (biceps brachii muscle) (c) Figure 7.11c, step 4b Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  29. 29. Types of Reflexes and Regulation  Somatic reflexes  Activation of skeletal muscles  Example: When you move your hand away from a hot stove Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  30. 30. Types of Reflexes and Regulation  Autonomic reflexes  Smooth muscle regulation  Heart and blood pressure regulation  Regulation of glands  Digestive system regulation Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  31. 31. Types of Reflexes and Regulation  Patellar, or knee-jerk, reflex is an example of a two-neuron reflex arc Figure 7.11d Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

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