See how much you know about action

potentials. As a team try to line these events up in the correct order.

Synapses… passing along important information

http://www.youtube.com/watch?v=70DyJwwFnkU

What is it?Synapse- the space where a neuron

communicates with another neuron, a muscle, or a glandWhere the electrical activity in one neuron

effects the excitability of another

What was a gap junction? In what body system did we talk about them?

2 types of synapses… 1. Electrical

plasma membranes of the presynaptic and postsynaptic cells are joined by a gap junction

Electrical impulse passes from cell to cell very quickly

In cardiac and smooth muscle NOT our focus!

2. Chemical- no physical connection between cells; need a messenger neurotransmitters

Sent neurotransmitter/message can:generate an action

potential/response from the receiving cell (excitatory synapse)

prevent the receiving cell from generating an AP/showing a response (inhibitory synapse)

How does a synapse work?1. If I told you muscles are “activated” the same way

resting neurons are excited, then what must be present during a synapse to make the muscle move?

2. Can these things (that will make muscles move) enter and exit the cell freely? Explain why or why not.

3. How will the neuron send a message to the receiving muscle cell?

4. Based on all of the answers to the above questions begin to formulate a theory about how neurons talk to muscle cells and tell them to move.

*THEORY:

Model it…Using the materials you have been given

design a sensible model that shows how a neuron can make a muscle move. Feel free to manipulate the materials as needed. Keep your answers to the previous questions in mind.

Identify what each material representsWhite cell:Red/pink cell:Pipecleaner:Pony beads:Beans:

Now…Merge with another group and explain

your models Discuss that aspects of the model are

plausible and which may need some refinement and see if you can create a better working model.

This final idea from the group duet will be shared with the class.

http://www.youtube.com/watch?v=HXx9qlJetSU

Events of a Chemical Synapse1. An AP stimulates the release of synaptic vessicles

(contain neurotransmitters) Vessicles bind w/ the terminal axon membrane

exocytosis2. Released NTs bind to receptor proteins on the

plasma membrane of the post-synaptic cell Excitatory response yes AP fired/receiving cell shows

response Inhibitory response no AP fired/receiving cell not

stimulatedNeurotransmitters don’t last for long b/c they are

either inactivated by enzymes taken back up by the axon terminal reuptake

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__transmission_across_a_synapse.html

What do you know?Get into your small groups from yesterdayIn a type 1 list the steps that occur, from start

to finish, that allow a neuron to talk to a muscle

NOW swap papers with another group, read their list of events and comment on anything that seems incorrect

Meet up with the group that has your paper and discuss the criticisms

Any questions?

Synaptic Integration*** 1 synapse is not usually enough to cause

activation but there are thousands of synapses occurring some happen close enough that their effects can add together to cause activation

http://www.youtube.com/watch?v=HXx9qlJetSU

Neuron-Muscle Communication1. Ach (Aceytlcholine)

is released from the nerveBoth Na and K channels open

simultaneously way more Na comes in than K goes out net increase

in charge10,000 ions cross in first millisecondCauses muscle to respond to stimulus

- Removed from synaptic cleft VERY FAST by an enzyme called acetylcholinesterase

Sarin inhibits this enzyme how? Nerve gas in Japanese terrorist attacks

http://www.youtube.com/watch?v=ra2HeSjo82c (start 6:08)

Neuron-Neuron Communication1. GABA

Major inhibitory NT in brainactually inhibits the signal and causes the

cell to go further from the threshold (Opens Cl- channels)

Valium increases GABA levels by increasing release of GABA Taken to relieve anxiety, muscle spasms, and

seizures

Neuron-Neuron Communication2. Dopamine

Involved in emotional behavior and motor control

Lack of dopamine causes Parkinsons (characterized by excessive shaking)

Amphetamines stimulate dopamine receptors why they’re addictive

When we are rewarded, feel good there are inc levels of dopamine

Neuron-Neuron Communication3. Serotonin

Serotonin involved in control of sleep and emotionLack of serotonin one cause of depressionMany antidepressants block the reuptake of

serotonin so effectiveness in increased more positive feelings

4. EndorphinsExample of a NEUROMODULATOR – which have

slower, longer effects on pre- or post- synaptic cells.Blocks perception of pain and evokes a feeling of

well-being Runner’s High lets you push yourself… sometimes too far