NEED HELP ASAP! 2. Imagine that a grizzly bear begins chasing you. You respond b
ID: 209184 • Letter: N
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NEED HELP ASAP!
2. Imagine that a grizzly bear begins chasing you. You respond by secreting norepinephrine (NE), a hormone that binds to pacemaker cells and increases the conductance/permeability of their low voltage-gated (leaky) Na+ channels and T-type Ca2+ channels. On the appropriate axes above, draw (with a dashed line) another trace showing how NE will alter membrane potential and AP frequency over time. Explain the channel mechanics underlying your answer.
3. NE affects L-type voltage-gated Ca2+ channels on contractile cardiomyocytes in a similar manner, by increasing their permeability to Ca2+ ions when they are stimulated. Given this, explain how and why the strength of ventricular contraction will change will change in response to NE.
1. Below are traces of membrane potential (and action potentials) over time of two types of cardiomyocytes: contractile cells and autorhythmic (pacemaker) cells. Note that the x-axes measure time, but are NOT on the same scale. Which one shows the potential changes occurring in pacemaker cells? Explain your choiceExplanation / Answer
2. First Graph
3. Norepinephrine increased ventricular contractile force and response is always transient, there is no increase in contractile force , but development of atrial fibrillation can be seen in response to NE, and the irregularity of the ventricular contractions makes accurate measurements of contractile force impossible.
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