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.