PHYSIOEX 9‚ ACTIVITY #3 Review Questions ACTIVITY #1 1. Explain why increasing extracellular K+ reduces the net diffusion of K+ out the neuron through the K+ leak channels? 2. Explain why increasing extracellular K+ causes the membrane potential to change to a less negative value. How well did the results compare with your predictions? 3. Explain why a change in extracellular Na+ did not significantly alter the membrane potential in the resting neuron? 4. Discuss the relative permeability
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through the 20 MWCO membrane? How well did the results compare with your prediction? Since the chemical formula for urea is (NH2)2CO and its molecular weight is about 60. It will not diffuse through the 20 MWCO membrane because it does not ionize. 3. Describe the results of the attempts to diffuse glucose and albumin through the 200 MWCO membrane. How well did the results compare with your prediction? Glucose will diffuse through the 200 MWCO membrane because its MW is 180. The MW of the protein
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results compare with your prediction? Your answer: If extracellular K+ is increased then the intracellular K+ will decrease. Fewer intracellular K+ ions would result in the membrane potential being less negative. This is what I predicted to happen. 3. Explain why a change in extracellular Na+ did not significantly alter the membrane potential in the resting neuron? Your answer: There are less sodium leak channels than potassium leak channels‚ and more of the potassium channels are open. 4. Discuss
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PhysioEX notes Autorhythmicity- heart’s ability to trigger its own contractions Phase O- a lot like depolarization in neuronal action potentials. Sodium channels open‚ increase of sodium INTO cell. Phase 1- sodium channels close‚ potassium channels close‚ decrease in potassium and sodium. Calcium channels open‚ increase of calcium into cell. Phase 2- Plateau phase‚ membrane still depolarized (contract). Potassium channels closed‚ L-type calcium channels stay open. Lasts 0.2 seconds/200
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Exercise 3: Neurophysiology of Nerve Impulses Worksheet Assignment Due: Week 4 Student instructions: Follow the step-by-step instructions for this exercise found in your text and record your answers in the spaces below. Submit this completed document by the assignment due date found in the Syllabus. Eliciting a Nerve Impulse Activity 1: Electrical Stimulation 1. Do you see any kind of response on the oscilloscope screen? Just a flat line. 2. What was the threshold voltage
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Activity 1 Pre-Lab Quiz K+ inside a cell = 150 mM; K+ outside a cell = 5 mM Na+ inside a cell = 5 mM; Na+ outside a cell = 150 mM Stop & Think question What is the polarity of the resting membrane potential (voltage)? Negative What does it mean that the voltage just inside the membrane is negative? B Membrane of most cells contains K+ leak channels…..b What will happen to the resting membrane potential if the extracellular K+ concentration is increase? Less negative What happens
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Activity 1 1. Increasing extracellular K+ reduces the net diffusion of K+ out of the neuron through the K+ leak channels because the membrane is permeable to K+ ions. Therefore‚ the K+ ions will diffuse down its concentration gradient from a region of higher concentration to a region of lower concentration. 2. Increasing extracellular K+ causes the membrane potential to change to a less negative value because the K+ ions diffuse out across the membrane. My results went well compared to my prediction
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Activity 1: Electrical Stimulation 1. Do you see any kind of response on the oscilloscope screen? NO 2. What was the threshold voltage‚ or the voltage at which you first saw an action potential? 3.0 V 3. How does this tracing compare to the one that was generated at the threshold voltage? The tracing travel in the same fashion but the tracing were different with an increase threshold voltage 4. What reason can you give for the change? Increase voltage 5. Record this maximal voltage here:
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Glomerular Filtration Activity 1: Effect of Arteriole Diameter on Glomerular Filtration 1. Compare this data with your baseline data. How did increasing the afferent arteriole radius affect glomerular filtration rate? >>Increasing the afferent arteriole radius pushed the glomerular pressure‚ the glomerular filtration rate‚ and the volume of urine to be higher than the baseline data. Increasing the afferent arteriole radius increased the glomerular filtration rate. 2. Under
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Exercise 2: Skeletal Muscle Physiology: Activity 3: The Effect of Stimulus Frequency on Skeletal Muscle Contraction Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. During a single twitch of a skeletal muscle You correctly answered: b. maximal force is never achieved. 2. When a skeletal muscle is repetitively stimulated‚ twitches can overlap each other and result in a stronger muscle contraction than a stand-alone twitch. This phenomenon is known as
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