NERVOUS SYSTEM AND ACTIVE TRANSPORTBig Ideas:
#2 (Homeostasis) & #4 (Interactions)
Basic Organization of the Nervous System
Organization of the Brain
Nervous Tissue
Functional Unit: Neuron
Communication Sequence
Potential in a neuron
What allows for the potential difference?
The sodium potassium pump uses ATP to maintain a charge differential inside and outside the neuron
Mechanism for the Sodium Potassium Exchange Pump
• Active Transport• Requires ATP• Movement against
the concentration gradient.
Role of facilitated diffusion
Movement of ions through gated channels is “down the concentration gradient” or passive
Action potential: The change in charge that propagates down a nerve cell and allows signals to travel over long distances.
• Watch the action potential animation.• http://outreach.mcb.harvard.edu/animations/
actionpotential_short.swf• While you are watching the animation, draw a nerve impulse and
identify the changes that cause the impulse to occur.
Action potential graph:
Propagation down an axon
Channels are concentrated in nodes of Ranvier
What happens when the signal gets to the end?
• Signal must cross a space (synapse) between:• 2 neurons• A neuron and a
muscle cell
• Signal changes:• ElectricalChemicalElectrical
To prepare for the next lecture:• Sketch and label a drawing of a basic nerve synapse.