Awake Brain Surgery: youtube/watch?v=rqWBDHRvHrQ&feature=related

1. Awake Brain Surgery: http://www.youtube.com/watch?v=rqWBDHRvHrQ&feature=related

2. Transduction of Nerve Signals 1. Into the neuron 2. Through the neuron 3. From neuron to neuron

3. Transduction of Nerve Signals 1. Into the neuron • Two main ways for a signal to enter a nerve cell (neuron) • Mechanical stimulation – through physical contact of the receptor of the sensory neuron with an object (senses heat, cold, texture, pain) • Chemical binding- of neurotransmitter molecules to receptors on the dendrites of a neuron

4. Transduction of Nerve Signals 2. Through the neuron • Chemical signal is carried from the dendrites, through the cell body to the axon • Action potential conducts the message along the length of the axon to the axon terminal • The key is the polarity of the axon membrane- determined by the concentration of Na+ and K+ ions along the inner and outer wall of axon membrane

5. Transduction of Nerve Signals

6. Transduction of Nerve Signals 3 pumps control these concentrations • K + leak channels • leak K+ out of axon • Na + channels • pump Na+ into of axon • Na + / K+ pumps • pump K+ back into axon and Na+ back out of axon

7. Action potential • Resting Potential • Membrane is polarized • Inside negative relative to outside • K+ leak channels open • Na+ channels and Na+ / K+ pumps are closed

8. Action potential • Resting Potential • Membrane is polarized • Inside negative relative to outside • K+ leak channels open • Na+ channels and Na+ / K+ pumps are closed • Action Potential • Membrane is depolarized • Outside negative relative to inside • Na+ channels open and K+ channels close • Na+ / K+ pumps are still closed

9. Action potential • Resting Potential • Membrane is polarized • Inside negative relative to outside • K+ leak channels open • Na+ channels and Na+ / K+ pumps are closed • Action Potential • Membrane is depolarized • Outside negative relative to inside • Na+ channels open and K+ channels close • Na+ / K+ pumps are still closed • Refractory Period • Membrane is repolarized • Inside negative relative to outside • Na+ channels close, Na+/K+ pumps open • K+ leak channels open at the end

10. Action potential http://highered.mcgraw-hill.com/olc/dl/120107/anim0013.swf http://www.blackwellpublishing.com/matthews/actionp.html

11. Transduction of Nerve Signals 1. Into the neuron 2. Through the neuron 3. From neuron to neuron

12. Transduction of Nerve Signals • 3. From neuron to neuron • Transmission of the signal from one neuron to another happens at the synapse • In the axon terminal, neurotransmitters (such as acetylcholine) are released into the synaptic cleft, where the molecules migrate to the surface of the dendrites • The neurotransmitters bind to the receptors on the surface of the dendrite membrane, and send a chemical signal into the cell body which generates a new action potential

13. Transduction of Nerve Signals • 3. From neuron to neuron http://highered.mcgraw-hill.com/olc/dl/120107/anim0015.swf http://www.blackwellpublishing.com/matthews/nmj.html

14. http://delicategeniusblog.com/?p=552