1. (Neuro)Glial cells- why are they important?
Make up 85% of the nervous system
Clear away cellular debris
Microglia repair
Astrocytes create the blood brain barrier
Oligodendrocytes help with the myelin sheaths 10

2. Ready… Aim… FIRE! Neurons have a negative “Resting Potential”
Nerve impulse = Action Potential
Resting potential= -70 mV
Action potential= All or none law 5

3. The nerve impulse: 100 million messages per second
50 billion neurons
10, 000 miles of fibers in 1 cubic inch.
Stretched out goes to the moon and back.

4. The Myelin sheath (formed by Schwann cells and oligodendrites) why is it important?
Myelin sheath is provided by which two neuroglia cells? – Schwann and oligodendrocytes
Acts as insulation
Action potential occurs only at the unmyelinated regions called the nodes of Ranvier. This is where the sodium channels are located
Insulated with myelin for speed
----Unmyelinatd axons speed of AP is 10 m/s.
Myelin sheath has spaces= Nodes of Ranvier.
----The AP jumps from node to node (speed 120 m/s).

5. Functional Properties of Neurons
Irritability – ability to respond to stimuli
Conductivity – ability to transmit an impulse
The plasma membrane at rest is polarized
Fewer positive ions are inside the cell than outside the cell

6. Starting a Nerve Impulse
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
Figure 7.9a–c

7. The Action Potential
If the action potential (nerve impulse) starts, it is propagated over the entire axon
K+ rush out of the neuron after Na+ ions rush in, which repolarizes the membrane
The Na+ - K+ pump restores the original configuration
This action requires ATP

8. http://www.sumanasinc.com/webcontent/ animations/content/synapse.html
animations/content/carrier_proteins.html

9. Nerve Impulse Continues b/w Neurons
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
Action potential is started again in the dendrite

10. How Neurons Communicate
Figure 7.10

11. Disease Multiple sclerosis destroys myelin sheaths.
Sodium (Na) channels are only at nodes.
Neuron can’t have an action potential or nerve impulse.
Disease that impact the myelin sheath, like MS, affect the action potential which impacts the action potential of that neuron. People with MS ultimately experience pain and decrease motor function in the areas of their body where the myelin sheath of the neurons has been effected.

12. Anesthetics = action potential
Local (Novocain, Xylocaine) attach to Na+ channel. Na+ can’t enter cell.
Anesthetia stops the action potential, stop the action potential and do you feel pain? – NO why? – the signal fro pain is stopped. Both local and general anesthesia prevent the change in polarity along the axis of the neuron.
General anesthetic (ether, chloroform) open K + channels, K + exits as fast as Na+ enters

13. The Reflex Arc
Reflex – rapid, predictable, and involuntary responses to stimuli
Reflex arc – direct route from a sensory neuron, to an interneuron, to an effector
Figure 7.11a

14. Types of Reflexes and Regulation
Autonomic reflexes
Smooth muscle regulation
Heart and blood pressure regulation
Regulation of glands
Digestive system regulation
Somatic reflexes
Activation of skeletal muscles

15. Reflex Arc

16. Reflex Arc Receptors Sensory neuron Relay neuron Motor neuron
Effectors