Thus, D glucose in aqueous solution exists as an equilibrium mixture of 5 compounds. The pyranose form predominates in solution.

aD glucofuranose (0.5%)

aD-glucopyranose (37%)

aldehydo- -glucose (0.003%)

bD-glucofuranose (0.5%)

bD-glucopyranose (62%)

TLS Online TPP Program

#Id: 5272

#Unit 7. System Physiology – Animal

Membrane ion channels that play important roles in generation of the action potential:

T (transient) channels 

L (long-lasting) channels

Voltage gated potassium ion channel

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#Id: 5273

#Unit 7. System Physiology – Animal

Between heartbeats, influx of positively charged sodium ions causes a slow rise in the resting membrane potential in the positive direction. 

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#Id: 5274

#Unit 7. System Physiology – Animal

When the potential reaches a threshold voltage of about −40 millivolts, the L-type calcium channels become “activated,” causing the action potential.

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#Id: 5275

#Unit 7. System Physiology – Animal

L-type calcium channels become inactivated (i.e., they close) within about 100 to 150 milliseconds after opening

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#Id: 5276

#Unit 7. System Physiology – Animal

When the L-type calcium channels become inactivated at about the same time, greatly increased numbers of potassium channels open.

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#Id: 5277

#Unit 7. System Physiology – Animal

Large quantities of positive potassium ions diffuse out of the SA node.