1. Nerve Impulses

3. How does an impulse travel along a nerve pathway
How does an impulse travel along a nerve pathway? Fill in your notes as you go.
Effector
Interneuron
Motor neuron
Receptor
Sensory neuron
Stimulus C B F D E A

4. Nerve impulses have a domino effect.
Through a chain of chemical events, the dendrites pick up an impulse that’s shuttled through the axon and transmitted to the next neuron.

5. The entire impulse passes through a neuron in about 7 milliseconds- faster than a lightning strike.

6. Step 1 Resting Potential (the nerve fiber is not sending a signal)
NaK pumps in the cell membrane actively transport 3 Na+ ions out of the cell for every 2 K+ ions pumped into the cell
The result- the interior of the cell is negatively charged with respect to the exterior- polarization

8. Step 2 Depolarization A threshold stimulus is received.
(the stimulation level that must be exceeded to elicit a nerve impulse)
Na+ channels in the membrane open and Na+ diffuses inward depolarizing the membrane

9. What charge are sodium ions?+
What will happen to the charge inside of the neuron?
It will become more +

10. Step 3 Repolarization K+ channels in the membrane open
K+ diffuse outward, repolarizing the membrane

11. Step 4 Action Potential
The resulting action potential causes a local bioelectric current that stimulates adjacent portions of the membrane
The wave of action potential travels the length of the nerve fiber as a nerve impulse

12. Summary of Nerve Impulse
Nerve impulse summary video

13. Dramatizing an Action Potential
2. What happens to the charge during an action potential?
1. What is the name of the stimulus that causes an action potential?
Threshold stimulus!!!!

14. Dramatizing an Action Potential
3. During rest, what is the charge on the outside of the cell membrane?
Resting
1. What part of the neuron does this rectangle represent?
Neuron
Cell Body
2. What branch is this?
Axon

15. Monday 12/11/17 Warm-up (complete hand out) Review
Synapse – structure and function
Project time

17. Summary of Nerve Impulse

18. Synaptic Transmission
Communication between a neuron and an adjacent cell occurs by neurotransmitters
Synapse
The site of communication between a neuron and another cell, such as another neuron or a muscle cell
Synaptic cleft:
Gap between two cells
Neurotransmitters diffuse across the gap
In the case of two neurons, the presynaptic neuron sends a message to the postsynaptic neuron

19. The Synapse

20. Structures of the synapse1
Presynaptic cell 2
Synaptic
knob 3 7 8 4 6 5
Postsynaptic cell
Axon, Dendrite, Mitochondria, Neurotransmitter, Receptor site, Synaptic cleft, Synaptic knob, Synaptic vesicle

21. What’s happening?
Arrival of the nerve impulse

22. Neurotransmitter binds to receptor
Arrival of the nerve impulse
Opening of the
calcium channels
Binding of Ca2+ to synaptic vesicles, neurotransmitter released into the gap
Neurotransmitter binds to
receptor
Na+ enter the Ligand-gated channel
Action potential generated in postsynaptic neuron

24. The Neurotransmitter synapse animation

25. Tuesday 12/12/17
What are the events/steps that occur in the synapse as the message is sent from one neuron to the next?

27. Synaptic transmission
Excitatory synapse
Binding of neurotransmitter to receptor opens Na+ channels
Allows Na+ to enter
Increase likelihood a nerve impulse(action potential) will begin in postsynaptic cell
Inhibitory synapse
Binding of neurotransmitter opens different ion channels
Less likely a threshold stimulus will be reached in postsynaptic cell
Cell’s interior becomes more negatively charged than usual
Cell will require larger than usual excitatory transmitter to reach threshold

28. Something else to think about…
Something else to think about….. The synaptic knobs of a thousand or more neurons may communicate with the dendrites and cell body of a single postsynaptic neuron. What will happen if both excitatory and inhibitory signals are received?

29. Summation of Input from Excitatory & Inhibitory Synapses
As many as 10,000 synapses with other neurons at the same time
Some with excitatory effects, others with inhibitory effects
Summation (combined effects) on neuron at any given moment determines if action potential is generated.
Integration of input gives nervous system fine control over responses

30. Removal of Neurotransmitter
After released, neurotransmitter quickly removed so their effects are temporary
If not removed, they continue to excite or inhibit the postsynaptic membrane indefinitely
Disposal: two ways

31. Wednesday 12/13/17
What are the two ways for the removal of a neurotransmitter from the synaptic cleft

32. Roles of Different Neurotransmitters
There are dozens of neurotransmitters
Some neurotransmitters produce different effects on different types of cells
Example: acetylcholine
Acts in both the PNS and the CNS
Released at every neuromuscular junction
Myasthenia gravis: autoimmune disease that attacks the acetylcholine receptors at neuromuscular junctions, resulting in little muscle strength

33. Roles of Different Neurotransmitters
In the CNS, different neurotransmitters are associated with different behavioral systems
Norepinephrine regulates mood, hunger, thirst, and sex drive
Serotonin promotes a feeling of well-being
Dopamine regulates emotions and complex movements

34. Presentation 12/14-12/15, Paper 12/18
Present abbreviated version of your minute routine (approx. 10 min)
Either present in person OR submit video BEFORE class (night before or by 7:45am the morning of)
You can use “pretend” weights, equipment, or machines BUT you need to clarify what you are using (name of equipment and the weight you are using)
All of the written work/components of the project are due at the beginning of class on Monday 12/18/17. NO electronic submissions (otherwise automatic 50% deduction in grade)
Check to make sure you have all components (see hand out)
Check spelling, grammar and punctuation (points will be deducted)
DO NOT wait until the last minute to print your paper! Too many things can (and often do) go wrong.
NO late submissions accepted

36. Presynaptic Neuron Postsynaptic Neuron Dendrite neurotransmitters
receptor
Na+
receptor
Axon
synapse
Dendrite
Cell Body
Cl-
Cell Body
Presynaptic Neuron
Synaptic knob
Postsynaptic Neuron

37. Explain the function of ATP in muscle contraction:
ATP binds to myosin head, allowing myosin heads to disengage from actin
Myosin heads split the ATP molecules to ADP and inorganic phosphate.
The energy released from splitting the ATP allows the myosin heads to swivel in preparation to form the cross-bridges.
Aerobic exercises initiate:
the development of new blood vessels to muscles
the development of more mitochondria to facilitate energy use
An increase in muscle coordination
Improvement of digestive tract movement
An increase in the strength of the skeleton by exerting force on the bones
Cardiovascular and respiratory system improvements that help muscles to function more efficiently