BIOD27H3 Chapter Notes -Action Potential, Cholinergic, Membrane Potential

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tauperhinoceros974

27 Sep 2011

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From what you know about proteins you should be able to figure out the. How is it that a channel protein (like the voltage gated na and. Thinking : prediction by hodgkin and huxley gating currents (1952, armstrong and bezanilla (1972, patch clamp (1982) sakmann and neher. Pancreas (islets of langerhans) right . (assignment 1) Research basis on type 2 diabetes a scientific reference point, a mouse model built from reality (super size me) Insulin simplified version of regulation of release. A model for studying mechanisms of impaired glucose tolerance (type 2 diabetes) Insulin has a role in fat metabolism (storage of tgs) A model for studying mechanisms of impaired glucose tolerance in type 2 diabetes. High-fat diet-fed c57bl/6 mouse model first in 1988. Insufficient islet cell compensation to insulin resistance. Basic defects: islet dysfunction in combination with insulin resistance. Gtt to determine responsiveness, measure plasma insulin (receptor vs. (cid:69)-cells)

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This is the peak depolarization in an action potential. At this point in an action potential two events start to happen.

1. Na+ channels begin to inactivate, which is equivalent to closing.

2. A majority of the K+ channels are beginning to open.

Determine what happens to the membrane potential when voltage-gated K+ channels are open simultaneously with voltage-gated Na+ channels (and the leak K+ channels which are still open). Increase the membrane permeability to K+ by increasing it to 115.

i. What happens to the membrane potential Em? __________________________

j. Why does the membrane potential change in this direction? __________________________ Now inactivate the voltage-gated Na+ channels by reducing the membrane permeability for Na+ back to 1. k. What is the new membrane potential? _____________

l. Is the new membrane potential less negative or more negative than the resting membrane potential listed in line âbâ of this section? _____________

m. Why? (hint: what 2 types of K+ channels are open now?) n. Under the current ionic concentrations given, what is the most negative value that the membrane potential could reach? _____________ (Increase the permeability of the membrane to K+ to confirm your answer.)

o. What equilibrium potential has the same value? _____________

p. At this point in the action potential, when the membrane potential is more negative than the resting potential, the membrane potential is said to be hyperpolarized. What happens to voltage-gated K+ channels (membrane permeability to K+) to bring the membrane potential back to its resting potential near -70mV?_____________

When the membrane potential became more negative than the Threshold potential, the inactivated voltage-gated Na+ channels became reactivated. After the voltage-gated K+ channels closed to enable the membrane potential to return to resting membrane potential they became ready to open again. Both channels are ready to open again in order to fire another action potentia

sapphirepanda54

Describe the structure of a voltage-gated sodium ion channel

Describe the function of the voltage-gate sodium ion channel. In your description, explain what is meant by channel gating and channel inactivation.

A) What parameters determine the specificity of K+ permeability in voltage-gated K+ channels?

B) How does the voltage sensitivity of K+ conductance contribute to the action potential?

BIOD27H3 Chapter Notes -Action Potential, Cholinergic, Membrane Potential

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