1. Nervous System

2. Two Regulatory Systems
Nervous System
Fast!
Short duration effect
Electric (ionic) signals …but also chemicals (neurotransmitters)
Affects nearby cells (local)
Endocrine System
Slower to start
Longer duration effect
Chemical signals (hormones)
Affects any cell (long distance)

3. NS & ES are Related 1. Neurosecretory Cells
In brain, but secrete hormones
Ex: epinephrine as hormone & neurotransmitter
2. Each system affects outcome of other
Ex: suckling…neurons…oxytocin…more milk
Ex: chemoreceptors detect glucose in blood…pancreas secretes insulin/glucagon

4. NS & ES are Related 3. Feedback Mechanisms Positive Negative
Ex: suckling/oxytocin
Negative
Ex: calcium levels/ PTH/calcitonin

5. Nervous System
The Cellular Level
Intro Video - Signaling

6. Neuron = Nerve Cell How does its structure fit its function? Axon
Dendrite
Myelin sheath

7. Gated Ion Channels open or close in response to 3 kinds of stimuli
Stretch–gated - in cells that sense stretch; open when membrane mechanically deformed
Ligand–gated - at synapses; open/close when specific neurotransmitter binds to channel
Voltage–gated - in axons; open/close when membrane potential changes
Gated ion channels are responsible for generating the signals of the nervous system

8. Membrane Potential the outside of the cell is more positive
the difference in charge while it is not “firing” is called the “resting potential”
Interactive Guide – Action Potential:
Video - Action Potential
Action Potential Cartoon –Self-Guided
Action Potential Video

9. Voltage-Gated Ion Channels
Resting state…more (+) outside than inside

10. Voltage-Gated Ion Channels
Stimulus causes Na channels to open

11. Voltage-Gated Ion Channels
Once enough Na+ moves in, membrane is “depolarized”

12. Voltage-Gated Ion Channels
Next, K+ gates open to allow them to move out…just as Na+ gates close… ”repolarization”

13. Voltage-Gated Ion Channels

14. Propagation of the Action Potential
How related to neuron?
As Na+ ions move in, the potential “flip-flops” triggering K+ gates to open
Meanwhile the Na+ ions diffuse over to next area causing the “flip-flop” in charge
And it goes on and on…

15. Propagation of the Action Potential

16. Saltatory Conduction
Action potentials can only be generated at nodes of Ranvier (myelin sheath blocks membrane)…message hops quickly

18. ~ More Na+ outside…more K+ inside (salty banana)
How do the Na/K concentrations return to resting state? …the Na-K Pump!
~ More Na+ outside…more K+ inside (salty banana)
~ K tends to leak out…leaving negative ions in
~ Na-K pump maintains this difference
Video – Sodium-Potassium Pump
Video - Sodium-Potassium Pump

19. Na-K Pump (Active Transport) More Na+ outside…more K+ inside
ATP allows movement of 3 Na out (uses 1 ATP) Then 2 K pulled in
Video – Sodium-Potassium Pump
Video - Sodium-Potassium Pump

20. A Chemical Synapse Video - Synapse Video – Synapse
Video - Synapse

21. A Chemical Synapse
Depolarization triggers Ca-channels to let Ca ions enter
Synaptic vesicles (w/ neurotransmitters) fuse with presynaptic membrane
Receptors on post-synaptic membrane bind neurotransmitter
Depolarization of gates carries message along

22. Integration of Multiple Synaptic Inputs
Each neuron makes connections with many other neurons

23. The Organs & their Functions
Nervous System
The Organs & their Functions

24. Overview of the Vertebrate Nervous System

25. Overview of the Vertebrate Nervous System
“Sensory receptor” – may be “special senses”
- light (vision), chemicals (taste & smell), movement (hearing)
Or…

26. Overview of Vertebrate Nervous System
“Sensory receptor” – may be general senses
- pressure, movement, temperature, chemicals, pain, location in space

27. Overview of Vertebrate Nervous System
Effector = skeletal, smooth, or cardiac muscle or glands

28. Diversity in Nervous Systems
Don’t need to memorize…just compare

29. Structural Divisions of the NS
CNS
Brain
Spinal cord
PNS
Nerves

30. Functional Divisions of the PNS
Sense
Move
Automatic
Choice
Rest & digest
Rev you up!

31. Parasympathetic & Sympathetic

32. Embryonic Brain Development
Don’t memorize…notice the pattern

33. Human Brain

34. Human Brain
Cerebrum – “thinking”; conscious actions; all the fancy stuff
Cerebellum – coordinates voluntary muscle movements
Brainstem – basic life functions (involuntary stuff)
Hypothalamus – homeostasis (hunger, thirst, etc)

35. Cerebrum – Functional Areas
The brain integrates most functions but there is some centralization…
Vision – hearing – higher though – motor/sensory – speech on left 35

36. Primary Motor/Somatosensory Areas of Cortex
Which motor areas get the most attention?
Why does that make sense?

37. Primary Motor/Somatosensory Areas of Cortex
Which sensory areas get the most attention?
Does that make sense?
Is this the same as for the motor cortex?

38. The Limbic System Memory – emotion - …
Note the association with the special senses

39. Reflexes Purpose – quickly respond to danger
What selection pressure for this to develop?

40. The Reflex Arc Components Stimulus - signal detected by sensory neuron
Sensory neuron carries msg to spinal cord
Decision made …U-turn at the interneuron
Motor neuron sends back reposnse
Effector – completes response; muscle or gland

41. The End