Module 6 Assignment Questions

Please fill in the blanks: A(n)    ["action potential", "muscle twitch", "contraction"]   consists of a wave of depolarization that moves along the plasma membrane of a neuron or a muscle fiber.  This wave of depolarization is immediately followed by repolarization.  Depolarization is when the cell's membrane potential becomes more   ["resting", "negative", "positive"]            .  Depolarization occurs when calcium channels open in the plasma membrane.  Repolarization is when the cell's membrane potential becomes more           ["resting", "positive", "negative"] , returning the cell to its resting potential.  Repolarization occurs when    ["calcium", "sodium", "potassium"]            channels close and    ["sodium", "calcium", "potassium"]    channels open.

what is the role of (1) electrochemical gradient created by ions, (2) permeability of the membrane proteins to such ions, (3) strength of stimulus, and (4) duration of the refractory period in the generation and propagation of action potential.

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Cardiac and skeletal muscle are both “striated” types of muscle and yet they have very distinct functional characteristics.  a) Skeletal muscle functions as discrete motor units and the cardiac muscle works as a functional syncytium.  Define the italicized terms in the previous sentence, explain their importance, and describe the cellular features that underlie these functional differences. b) Cardiac muscle exhibits automaticity, while excitation of skeletal muscle is neurogenic.  Define the italicized terms and provide a brief explanation of mechanisms underlying each.

10. Other types of cells, called glia, greatly outnumber neurons in the CNS. These cells are shown below. For each, label the glial cell type and give one or more functions that each serves. a) Cell Type: (b) Cell Type: Function: Function: (b) (a) (d) Cell Type: c) Cell Type: Function: Function: (d) Dopymghe 200s Pon Ed Inc pubhing Benjamin Cumming 11. A simple reflex arc is a wired circuit delivering information to and from the central nervous system. Use the diagram to label the structures. Then briefly describe the type of signal that must pass along one cell, cross, and then affect the next cell in the chain. Use the words of neuroanatomy. The signal:

The resting membrane potential…A) Can be approximated using the Nernst equation.B) Is established by a difference in charges across the cell membrane, with the inside more positive than the outside.C) Has no influence on the driving force for flow of a particular ion across the cell membrane.D) Is more dependent on the passive flow of potassium vs. sodium ions through leak channels across the cell membrane.E) Stays the same during an action potential.

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The differences in relative concentrations of ions inside and outside the cell act as an electrical force. The specific ion(s) MOST important to establishing the resting potential in neurons would be Multiple Choice   a) Na+.   b) K+.   c) intracellular anions (e.g., proteins).   d) H+.             e) Na+, K+, and intracellular anions are all important.

please answer 18,19,20,

9. If sodium permeability (Pna) increases compared to normal, what is the effect on the membrane potential? (determine: change in charge on the inside of the membrane and polarity)

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60. The action potential of a normal axon is shown on the graph. K* conductance is maximal at which of the following labeled locations? HA B D A -90- 1 2 3 4 6 Time (msec) C) A) Membrane potential (mv) B) 5 D) E)

Match each type of membrane potential (resting, threshold, graded, or action) to its definition: a) The membrane potential at which voltage gated sodium channels open. b) The membrane potential that triggers the action potential. c) Change in membrane potential that may or may not reach threshold and that may be depolarizing or hyperpolarizing. d) Rapid, strong depolarization followed by immediate repolarization. This potential is self-renewing if the right ion channels are nearby.

a) How does E allow faster transmission of signals?  b) What would happen if G has a lack of Calcium? c) Most neurons have the style of junction (chemical) shown in the diagram, rather than gap (electrical) junctions. Why does this make sense?

Transmission of electrical signals in nerve and muscle cell is mediated by opening and closing of: 1) ion channels in the nuclear envelope  2) ion channels in the plasma membrane  3) the electron transport chain 4) the sodium potassium ATPase in the plasma membrane

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1.[#113] What is the operating voltage of the computer in your head? (1 ans only) The answer to this question (which we hope you'll find interesting) is in the lesson 1.1 movie. The question is here partly because we want you to get in the habit of reviewing the lesson if the question seems too difficult. The human brain uses binary pulse signals with typical voltages of: a.) ~ 0.01 volt (i.e. roughly between 0.003 V and 0.03 V) b.) ~ 0.1 volt (i.e. roughly between 0.03 V and 0.3 V) c.) ~ 1 volt (i.e. roughly between 0.3 V and 3 V) d.) ~ 10 volt (i.e. roughly between 3 V and 30 V) e.) ~ 100 volt (i.e. roughly between 30 V and 300 V) f.) ~ 1 killervolt (sorry, I couldn't help myself) g.) 5 V in the TTL model, but mine is CMOS   2.[#114] The age of the universe Going back to one of those big questions: Cosmologists tell us that the universe is 14 billion years old. Hooee, that's quite a while! But how long is that in seconds? Hint:…

Please answer both  1) What is responsible for returning the cell to its normal resting membrane potential following the absolute refractory period? a) K+ leak channels b) the Na+/K+ pump c) activation of voltage-gated Na+ channels d) a ligand binding to a ligand-gated Na+ channel 2) What property of an action potential allows it to propagate? a) the rapid period of depolarization b) the rapid period of repolarization c) the brief period of hyperpolarization d) the fact that the peak is 85 mV above threshold

The sodium-potassium pump is really important to the functioning of neurons. (a) What does it do? (b) Why type of transport is it responsible for? Explain. (c) Imagine a person is exposed to a drug that destroys the sodium-potassium pump. How will this impact their neuron? Explain.

What is the difference between the membrane potential in a normal cell and an excitable cell?