Awake Brain Surgery:
Transduction of Nerve Signals 1. Into the neuron 2. Through the neuron 3. From neuron to neuron
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
Transduction of Nerve Signals 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 2. Through the neuron
Transduction of Nerve Signals
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 3 pumps control these concentrations
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 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
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
Action potential
Transduction of Nerve Signals 1. Into the neuron 2. Through the neuron 3. From neuron to neuron
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
Transduction of Nerve Signals 3. From neuron to neuron