Hyperpolarizing

 Hyperpolarizing graded potentials can be caused by K+ leaving the cell or Cl- entering the cell.

 If a positive charge moves out of a cell, the cell becomes more negative; if a negative charge enters the cell, the same thing happens.

 Our patient had an injury to the thoracic spinal cord which impacted her sympathetic nervous system.

Although more rare, what type of spinal cord injury would have impacted the parasympathetic nervous system?

  

injury to the sacral region

 

  

injury to the lumbar region

 

this would impact the sympathetic nervous system. check your notes again

  

injury to cranial nerves

 

Autonomic nervous system | Organ Systems | MCAT | Khan Academy

2-Minute Neuroscience: Parasympathetic Nervous System

Exam 1: Friday 5/10 in person (the lecture hall 8402)

Exam 1: Friday 5/10 in person (the lecture hall 8402)

Details:

• ~30 MC or T/F style questions (still writing up the exam, but somewhere in this range!)
  • Dr. Y will bring scantrons, you don't need to purchase those.
• ~5 short response where you will explain your answer to 5 of the MC’s above
• Remember you have seen these questions in lecture during our class discussions OR on handouts
  • That means you have practiced this question and we’ve reviewed it together. The exam is the 2nd or even 3rd time you’ve practiced the idea
  • The wording might change a bit but the concept tested is the same
• The exam is designed to take around 1 hour, but you have the full 1hr and 50 minutes so you can take your time

 

What should I study?

• Remember that you’ve been consistently reviewing each week during your post-class assignments so hopefully the questions below will be review/familiar!
• You should take a careful look at all our in-class handouts & any questions I posed during our lectures. The majority of questions are based on those handouts and in-class questions. In addition, short response/explain your answers will always be pulled from questions we discussed/debriefed together in lecture so you should feel comfortable explaining your answer or reasoning.
  • You should also take a look at post-class questions as well
  • Please don't memorize. Focus on being able to do the process/answer the question. If I told you about ion "A"'s concentration gradient and charge (instead of mentioning K+ or Na+), can you still answer the question about which direction the ion moves and what effect this will have on the membrane potential?
• Compiled questions from lecture to review here.Download Compiled questions from lecture to review here.
  • Updated for Spring 24!!!
    (Final version, it is not pretty, but it is compilation of nearly all the activities/questions we went through in lecture together in one place). If you can tackle these questions again but this time on your own, without having to go back to your notes then you probably have a pretty solid understanding of the material we covered. Be prepared to be able to explain your thinking too as there are some short response questions.
    
• Practice Quizzes (were posted weekly for each week resource page):
  • Week 2 Practice Quiz
  • Week 3 Practice Quiz
  • Week 4 Practice quiz
  • No practice quiz for Week 1

 

What can I bring?

• Summary sheets from Weeks 1-5. You will turn these in with your exam.
• NO questions & answers (I would consider this a form of cheating and you would have a penalty placed on your midterm)
  • For example from the Lecture 8 Handout,
    Parasympathetic NS would release Ach to Type 1 Muscarinic Receptors on cardiac muscle cells.
    
  • For example from Post-Class 3 Quiz, 

    What is the effect of the SSRIs on the serotonin concentration in the synaptic cleft?

    The serotonin concentration in the synaptic cleft will decrease.

    The serotonin concentration in the synaptic cleft will increase.

 

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Guiding questions

In the ideal case, you have been regularly reviewing these questions weekly (these are the same Guiding Questions from each week, I just copied and pasted so they are all in once place). If at this point you are just starting to look at the questions, then only use the questions below to identify areas you need to review. In other words, for efficient studying, I don’t recommend sitting down and answering all the questions (that will take a long time and potentially distract you away from reviewing in-class questions/handouts).  

Rather, you should read through the questions below, and highlight or circle the ones you can’t answer. Then, you can revisit your notes/lecture slides that you need to spend more time on. Please reach out to Dr. Y if that didn’t make sense! Please don’t get overwhelmed, the list is meant to be a comprehensive list of questions that review everything we covered the last 4 weeks.

 

Membrane dynamics & membrane potential

• Describe several ways that intracellular fluid (ICF) differs from extracellular fluid (ECF). What ions are higher in the ICF vs ECF?
• Describe what a concentration gradient is and how it leads to diffusion and the establishment of a dynamic Can you identify the flow of ions in/out of cells based on concentration gradients?
• Describe the mechanism of the Na+/K+ pump and explain how it contributes to the resting membrane potential of a cell.
  • What would happen to the resting membrane potential if the Na+/K+ pump was mutated and not working?
• Describe the mechanism of Na+ and K+ leak channels. How do they contribute to the resting membrane potential of a cell? How do they contribute to membrane permeability?
• What is the resting membrane potential? What voltage value is it typically for most cells in your body?
• If the concentration gradient of K+ decreases across the cell membrane, what happens to the membrane potential?
  • If the cell all the sudden became permeable (think gated membrane channels opening) to K+, what would happen to membrane potential? What about Ca2+? Na+?
• What is hyperpolarization vs depolarization of the membrane potential? What ion channels should be opened to cause either?

 

Graded Potentials

• Draw and describe the structure of a neuron.
  • Identify each of the following structures on your drawing and describe their structures: dendrites, dendritic spines, cell body, axon, axon hillock, collateral, axon terminal, synapse, postsynaptic cell

• Where are the sensory receptors located on a neuron? From where on the neuron are neurotransmitters released?

• Where do graded potentials occur?

• What type of stimuli causes a graded potential? How does the strength of the stimulus affect the amplitude of the graded potential?

• As a graded potential travels through the cell body, they lose amplitude. Explain why.

• What is an EPSP? What is an IPSP? What ion channels contribute to each? Are each caused by depolarizations or hyperpolarizations?
  • How does an EPSP contribute to triggering an action potential? What about an IPSP?

 

Action Potentials

• Differentiate between graded potentials and action potentials.
• Where in the neuron do action potentials occur?
  • How does the strength of the stimulus effect the amplitude of the action potential? Why are they all-or-none?
• Explain how ion permeability changes during the rising phase and falling phase of an action potential.

• What is the stimulus for opening EACH of the channels used during an action potential?
• What is the order of stimulus, opening and closing of all of these channels?
• How is the resting membrane potential reestablished after an action potential?
• Hint, we did this for our in-class activity! Can you visualize what’s happening with each of the channels?

• Voltage gated Na+ channels in the axon contain two gates. What are they? How are they triggered?

• What are the absolute and relative refractory periods?

• How does the inactivation gate on the Na+ channel cause the absolute refractory period?

• What causes the relative refractory period?

• How are action potentials conducted along the length of the neuron?
  • Why don’t action potentials lose amplitude along the length of the axon?

• If action potentials all have the same amplitude, how do action potentials transmit the intensity of the signal (to phrase it a different way, how do neurons alter the amount of neurotransmitter release based on the size of the stimulus?)?
• Explain how myelin increases conduction speed down the length of an axon.
  • Explain the mechanism of salutatory conduction
    

• What is the effect of demyelination? What are the symptoms of demyelination diseases (multiple sclerosis).

  

Synaptic Transmission

• Draw and label the components of a synapse. Be sure to label the following structures: presynaptic cell, axon terminal, synaptic cleft, and postsynaptic cell (either neuronal or non neuronal)
• What is the difference between a chemical and electrical synapse?
• What is the trigger for neurotransmitter release from a synapse? Outline the steps of synaptic transmission.
  • How is neurotransmitter release terminated?

• How is synaptic activity terminated (be sure to talk about all three mechanisms)?

• Differentiate between “FAST” receptors and “SLOW” receptors on a post synaptic cell.
  • Explain how neurotransmitter binding to a fast receptor might cause an EPSP in the post synaptic cell. How about and IPSP?

• Explain how a neurotransmitter binding to a slow receptor might cause an EPSP in the post synaptic cell. How about an IPSP?

• What is long-term potentiation (LTP)? What is the neurotransmitter that governs LTP?
• What are the neurotransmitter receptors involved in LTP?
  • What is the result of glutamate binding to AMPA? Is this a fast response or a slow response?

• What about NMDA receptors?

• Describe the sequence of events that occurs when glutamate is released from the presynaptic cell. How do these events lead to LTP?
• Describe the structure of the synapse of the neuromuscular junction.
  • What is the neurotransmitter released from a somatic motor neuron?

• • What is the receptor on the muscle cell? Does triggering this receptor with neurotransmitter trigger a fast response or a slow response?

• • Describe the sequence of events that occurs when an action potential reaches the axon terminal of a somatic motor neuron.

• • How is synaptic transmission terminated at a neuromuscular junction?

• • What is AChE and what does it do at the synaptic cleft?

• What is an agonist and how does it affect synaptic transmission? Give examples of both direct and indirect agonists.

• What is an antagonist and how does it affect synaptic transmission? Give examples of both direct and indirect antagonist
• Explain how GABA work to inhibit post-synaptic cell response.
  • How would blocking GABA receptors affect response in the post-synaptic cell?
  • Hint, remember our in-class handout!
• Make a list of all of the ion channels we have discussed. Make sure you indicate where you find the channel, how it is gated, which way ions will travel through it and their effect on membrane potential and when it is used.
  • Make a list of all of the neurotransmitter-receptor pairs we have discussed. Make sure you indicate where the neurotransmitters are used and how they are regulated
  • Hint, we did a lot of this in our in-class handouts!

 

Peripheral Nervous System

• Describe the organization of the nervous system.
  • Be sure to use the following terms: efferent neurons, afferent neurons, sensory receptors, autonomic neurons, somatic motor neurons, parasympathetic neurons, sympathetic neurons, somatic motor neurons, skeletal muscles, central nervous system, peripheral nervous system.
• What does the somatic motor division of the efferent nervous system control?
  • Describe the structure, target, neurotransmitter and receptor and enzyme used in the somatic motor division.
• What are the two divisions of the autonomic nervous system?
  • What are the targets of the autonomic nervous system?
  • How are pre and postganglionic neurons similar and different in the sympathetic vs parasympathetic divisions?
  • Describe how the two divisions of the autonomic nervous system maintain homeostasis through antagonistic control.
  • Give several examples of antagonistic control carried out by the autonomic nervous system.
  • Describe how the preganglionic neuron and the postganglionic neurons are arranged in the sympathetic and parasympathetic systems.

• What neurotransmitter-receptor pair is used in the autonomic ganglion of BOTH divisions of the autonomic nervous system?
  • How are the postganglionic autonomic synapses similar and different than the synapses in the neuromuscular junction?
  • Hint, a lot of this work is summarized by your in-class handout!

• In the sympathetic division, what neurotransmitter-receptor pair is used in the ganglion? What about at the postganglionic synapse?
  • Give several examples of how the parasympathetic system affects different tissues (for example, how does it affect heart rate, salivation, rate of digestion, airways)
  • Describe how different types of adrenergic receptors can cause different responses to the same neurotransmitter.
    • As an example, explain how this works to modulate the diameter of arteries in the digestive system and blood vessels in the skeletal muscles during a systemic sympathetic response.
    • Hint, this is summarized in your in-class handout!
  • You can review the adrenal medulla material (it will be relevant in 40C as well), but note I won’t ask you any questions about it!
• In the parasympathetic division, what neurotransmitter-receptor pair is used in the ganglion? What about at the postganglionic synapse?
  • Compare and contrast nicotinic receptors and muscarinic receptors.

• • Give several examples of how the parasympathetic system affects different tissues (for example, how does it affect heart rate, salivation, rate of digestion, airways)

• • Again, this is summarized by our in-class activity!