1. Neuron Function
Ch. 7b

2. Functional Classification of Neurons
Sensory (afferent) neurons
Carry impulses from the sensory receptors
Cutaneous sense organs
Proprioceptors – detect stretch or tension
Motor (efferent) neurons
Carry impulses from the central nervous system
Slide 7.14a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

3. Functional Classification of Neurons
Interneurons (association neurons)
Found in neural pathways in the central nervous system
Connect sensory and motor neurons
Slide 7.14b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

4. Neuron Classification
Figure 7.6
Slide 7.15
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

5. Quick Quiz 1 of 3
What are the three functional types of neurons and what does each do?

6. Structural Classification of Neurons
Multipolar neurons – many extensions from the cell body
Figure 7.8a
Slide 7.16a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

7. Structural Classification of Neurons
Bipolar neurons – one axon and one dendrite
Figure 7.8b
Slide 7.16b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

8. Structural Classification of Neurons
Unipolar neurons – have a short single process leaving the cell body
Figure 7.8c
Slide 7.16c
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

9. Seniors, 3 more Mondays!
Get your Neuron Model out that you worked on last week.
We will get materials once class begins.
If you have sub work from Thursday staple it and turn it in to tray.
**If you missed test, you need to make it up during a lunch period**

10. Challenge Problem
Get out the lab from Mon- I will collect when bell rings 1. List the 5 steps of a reflex arc 2. Which organ gets skipped in a reflex arc? 3. Can you train yourself to react faster to things? 4. If you think you can, give an example 5. The reaction of the pupil to light and the knee jerk to the hammer are examples of __________.

11. How fast is your reaction time?
Distance
Time
2 in (~5 cm)
0.10 sec (100 ms)
4 in (~10 cm)
0.14 sec (140 ms)
6 in (~15 cm)
0.17 sec (170 ms)
8 in (~20 cm)
0.20 sec (200 ms)
10 in (~25.5 cm)
0.23 sec (230 ms)
12 in (~30.5 cm)
0.25 sec (250 ms)
17 in (~43 cm)
0.30 sec (300 ms)
24 in (~61 cm)
0.35 sec (350 ms)
31 in (~79 cm)
0.40 sec (400 ms)
39 in (~99 cm)
0.45 sec (450 ms)
48 in (~123 cm)
0.50 sec (500 ms)
69 in (~175 cm)
0.60 sec (600 ms)

12. Get Crossword puzzle You have 30 min The book may be helpful
I will give a few answers 15 min

13. Functional Properties of Neurons
Irritability
ability to respond to stimuli
Conductivity
ability to transmit an impulse
Polarized plasma membrane
at rest plasma membrane is polarized
Negative inside, positive outside the cell
Slide 7.17
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

14. Starting a Nerve Impulse
Depolarization
a stimulus depolarizes the neuron’s membrane
A depolarized membrane allows positive ions of sodium (Na+) to flow inside the membrane
The exchange of ions initiates an action potential in the neuron
Figure 7.9a–c
Slide 7.18
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

15. The Action Potential
If the action potential (nerve impulse) starts, it propagates through the entire neuron
Negative Potassium ions rush out of the neuron after positive sodium ions rush in, which repolarizes the membrane
The sodium-potassium pump restores the original configuration
This action requires ATP
Slide 7.19
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

16. Nerve Impulse Propagation
The impulse continues to move toward the cell body
Impulses travel faster when fibers have a myelin sheath
Figure 7.9c–e
Slide 7.20
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

17. Continuation of the Nerve Impulse between 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
An action potential is started in the dendrite
Slide 7.21
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

18. A Nerve Impulse: The short story
Stimulus excites dendrites
Cell membrane begins to depolarize
Impulse travels from dendrites through cell body through axon, depolarizing the whole way.
After the impulse passes a part of the neuron, the sodium-potassium pump restores the resting potential of the membrane
The impulse leaves the axonal terminals via neurotransmitters, which excite the next neuron’s dendrites

19. How Neurons Communicate at Synapses
Figure 7.10
Slide 7.22
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

20. Quick Quiz 2 of 3
Explain how a nerve impulse travels through a neuron.
What is the purpose of neurotransmitters?

21. Challenge Problem
These neurons take messages from the CNS to muscles and glands.
These neurons are only found in the CNS
The gap between neurons is called the _______.
The way cells communicate between one another is electrical or chemical?
Nerve impulses enter the neuron at the _______ and exit the neuron at the _____

22. Get your neuron model out
Make a pile of your models at your table
Have the tallest person take your models to the next table according to the board
Use the instruction sheet to determine if all the criteria are present on the model

23. Scoring Guide 1 pt for unipolar sensory neuron
11pts total for all 11 criteria
3 pts possible for neatness and creativity
Total= 15pts

24. 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
Skips the brain!!
Figure 7.11a
Slide 7.23
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

25. Simple Reflex Arc Slide 7.24 Figure 7.11b, c
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

26. 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
Slide 7.25
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

27. Quick Quiz 3 of 3
What important organ is skipped in processing a reflex reaction?
Explain the journey of a nerve impulse in a reflex arc.

28. Challenge Problem List the steps of a reflex arc.
Which organ in the body gets skipped during a reflex arc?
Why do you think it is important that this organ gets skipped?
Interneurons are only found in ______
Get out the lab we began Tuesday or get one from the front

29. Observing Nervous Responses
Read the entire lab again
I will demo 3 parts
You will complete lab and answer analysis questions.
We will finish 7b notes beginning at 9:10

30. Get your Neuron Model stuff out
You have ~50 min to complete
When finished
Get worksheet from front to complete