New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

Week 1, Lecture 2 Notes

by: Malissa Notetaker

Week 1, Lecture 2 Notes Biol-K416

Malissa Notetaker

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

For Exam 1
Cell & Molecular Neuroscience
Dr. Jason Meyer
Class Notes
25 ?




Popular in Cell & Molecular Neuroscience

Popular in Neuroscience

This 5 page Class Notes was uploaded by Malissa Notetaker on Monday September 5, 2016. The Class Notes belongs to Biol-K416 at Indiana University Purdue University - Indianapolis taught by Dr. Jason Meyer in Fall 2016. Since its upload, it has received 7 views. For similar materials see Cell & Molecular Neuroscience in Neuroscience at Indiana University Purdue University - Indianapolis.

Similar to Biol-K416 at IUPUI

Popular in Neuroscience


Reviews for Week 1, Lecture 2 Notes


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 09/05/16
Cellular and Molecular Neuroscience   Lecture 2­ 8/24/16    Topic: How do neurons convey signals throughout the nervous system?    ● Neurons inherently have an internal negative charge ​​ elative to the outside  ○ NOT an absolute negative charge  ○ Have a means of generating constant voltage across their membranes ​when at rest  ■ Known as ​resting membrane potential  ■ Usually around ­70mV, but can be between ­40 mV and ­90 mV, but  depends on type of neuron  ■ Potential Test question: ​“Which of the following would most likely be  the charge of a neuron at rest?”  ● ­100mV  ● ­70mV  ● ­20mV  ● +50mV    ● Electrical signals produced by neurons are caused by responses to stimuli  ○ Stimuli act to change resting membrane potential, either making it more positive  or more negative  ○ Three types of stimuli  ■ Receptor potentials  ■ Synaptic potentials  ■ Action potentials    ● Receptor Potentials  ○ Created due to activation of sensory neurons by external stimuli  ■ Light­ photoreceptors in eye  ■ Heat­ receptors in skin  ■ pressure/touch  ■ Sound   ■ Smells  ■ Tastes  ○ Converted to nervous system impulse  ○ Pacinian corpuscles­ receptor neurons that sense mechanical disturbances in skin  ■ Respond to touch w/ a receptor potential that changes the resting  membrane potential for a fraction of a second   ■ Respond by making some kind of receptor potential ­ change in charge  across membrane  ○ After change in resting membrane potential, sensitization/ habituation will occur  ■ Allow response to stimuli to change  ■ Ex­ put on clothes in the morning, but you aren’t aware of the feeling of  clothes on your body all day    ● Activity of cortical neurons:  ○ Center of the receptive field (where the touch takes place)­ increased cell firing  ○ Surrounding of receptive field­ decreased firing  ○ Outside receptive field­ no effect on firing  ○ Helps show us exactly where the disturbance is    ● Synaptic Potentials   ○ Allow transfer of info from one neuron to another neuron across synapse  ○ Causes a brief change in resting potential of post­synaptic (more downstream)  neuron  ○ Serves as a means of info exchange in complex neural circuits  ○ Magnitude for synaptic & receptor potentials are around the same    ● Action Potentials  ○ Neurons that create this signal that travels along axon  ○ Responsible for long­range transmission of info in nervous system  ○ Membrane potential change is >>> than in synaptic or receptor  ■ Repolarization & depolarization occurs faster  ■ More consistent   ○ Has hyperpolarization  ○ Current delivered to neuron that makes membrane potential more negative is  hyperpolarization​ (or repolarization)   ■ Nothing really happens, referred to as ​passive electrical response  ○ Current delivered to neuron makes the membrane potential more +, called  depolarization  ■ If membrane potential becomes + enough & reaches ​threshold potential​,  will result in an action potential  ○ Synaptic is kind of a precursor to action    ● Characteristics of Action Potentials   ○ Usually brief (~1 ms) change from ­ to + charge of membrane potential  ○ Amplitude of action potential is ​NOT​ necessarily due to magnitude of current  used to evoke it  ○ Action potentials are ​all or nothing​­ if an action potential is evoked at all, it will  be of the same amplitude regardless of strength of stimulus  ■ But magnitude of stimulus CAN affect the FREQUENCY of the action  potential firing  ○ Depolarization that doesn’t hit the threshold line is probably synaptic, not an  action potential until it reaches threshold  ○ Action potentials are all capping out @ the same level­ “all or none”  ■ But increase in frequency of action potential means increase in the current    ● Long­Distance Transmission of Electrical Signals  ○ Axons can be very long, can even extend over a meter  ○ Are VERY poor conductors of electricity  ○ If depolarization event is too small to elicit action potential, signal that is traveling  will rapidly degrade, usually within a few millimeters  ■ Occurs because the current “leaks” out across axon’s membrane  ○ But signal will NOT decay down the axon if the stimulus is large enough to  generate an action potential  ■ As it goes down the axon, same strength but delayed  ■ “All or none” action potential    ● Ion Movements Produce Electrical Signals  ○ Electrical potentials are generated across membranes due to 2 mechanisms:  ■ Differences in concentrations of specific ions across nerve cell membranes  ■ Membranes are selectively permeable to some of the ions    ● Squid Giant Axon is 400x larger than mammalian axon, making it a better to study with    ● Know which ions are > inside or outside the neuron  ○ Potassium is > inside  ○ Sodium is > outside  ○ Chloride is > outside   ○ Calcium is > outside    ● Ion Movements Produce Electrical Signals (continued)  ○ Active Transporters­ actively move ions in or out of cells against concentration  gradient  ■ Create ion concentration gradients  ■ Can make the outside more + than inside  ○ Ion channels­ allow only certain kinds of ions to cross the membrane in the  direction of their gradients  ■ Are selectively permeable to certain ions    ● How An Electrochemical Equilibrium is Established  ○ Can be demonstrated through the use of an artificial membrane that separates 2  compartments containing solutions of ions  ■ Left side is “inside” of cell and right side is “outside”  ■ If concentration of ions is =, there will be no electrical potential measured  across it  ● No net flux of ions  ■ If concentration of K₊ ions is NOT the same on both sides, electrical  potential will be created  ■ If higher inside, electrical potential inside will become more negative  relative to outside due to K₊ ions flowing down concentration gradient  ○ Neuronal membranes CAN pump K₊ into cell  ■ Have K₊ permeable channels in membrane to allow K₊ flow out of cell  ₊​ ● Continual resting efflux of K  ​is responsible for resting membrane  potential  ○ Remember chemical gradient vs. chemical gradient  ■ Chemical gradient­ sheer amount of ions (one side vs. the other)  ■ Electrical gradient­ charge of ions    ● Electrochemical Equilibrium  ○ A point where there is no net flow of ions (in the case K₊) out of the cell  ■ Generally in or out of the cell  ○ Due to 2 opposing forces  ■ There is always a higher concentration of K₊ ions inside the cell  ■ As membrane potential changes, electrical gradient works to stop K₊ from  moving across the membrane  ○ Thus establishing resting membrane potential    ● To move ions, NEED ion channels, then can pass through  ○ Ions can only go through their specific channels    ● Movement of ions depends on BOTH electrical and chemical gradient    ● Tetrodotoxin, TTX, poison from pufferfish  ○ Will selectively bind & block sodium ion channels    ● Tetraethylammonium, TEA, will selectively block certain K₊ channels    ● What ions are involved in the action potential?  ○ Beginning of resting state­ Pk>>> Pna  ○ Depolarization­ Pna increases  ■ Due to opening of Na channels, rushes in  ○ Peak of action potential­ Pna>>>Pk  ○ Repolarization­ decrease of Pna  ■ Increased permeability to K₊  ○ Back to resting state  ■ Pk>>>Pna    ● Components of an Action Potential­  ○ Rising and overshoot phase due to increased membrane permeability to Na+  ■ Depolarization  ○ Falling phase due to activation of voltage­gated K₊ channels  ■ Repolarization  ○ Undershoot phase due to K₊ ion channels  ■ Hyperpolarization             


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Jennifer McGill UCSF Med School

"Selling my MCAT study guides and notes has been a great source of side revenue while I'm in school. Some months I'm making over $500! Plus, it makes me happy knowing that I'm helping future med students with their MCAT."

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.