BIOLOGY 3P03 Lecture Notes - Lecture 6: Colander, Resting Potential, Current Source

82 views6 pages

pucesheep271

19 Oct 2017

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Resting membrane potential (rmp) (vm, em) is generated by the unequal distribution of ions, k+, na+, and cl-, across the plaza membrane: rmp is closer to k+ potential because the cell is more permeable to potassium ions. The distribution of ions is maintained by ionic pumps and exchangers. K+ ions are concentrated inside the neuron and tend to ow down their concentration gradient, leading to hyperpolarization (k+ moves out making inside more negative) The resting membrane is also permeable to na+ and cl- so rmp can range from -70 to -45 mv: signi cantly positive to ek. For spherical cell: instantaneous" current injection causes exponential rise in voltage: slowing due to capacitance properties (i. e. it takes time to charge (and discharge) a capacitor. Rin is simple for a spherical cell; it is the membrane resistance rm, which in turn depends on the surface area a" of the sphere (note a is proportional to r2)

Related Questions

(1) What would be thelikely outcome if an increase in both intracellular sodium ionlevels and extracellular potassium ion levels were tooccur?

A: The Na+-K+ pump would accelerate because it needs to restorethe membrane's resting concentration gradient.

B: The Na+-K+ pump would slow down because it needs to restorethe membrane's concentration gradient.

C: Sodium and Potassium ions would be pumped out of thecell.

D: Sodium and Potassium ions would increase their movement inboth directions across the cell membrane.

(2) Due to the unequal transport of sodium and potassiumions by the Na-K pump, a membrane potential isgenerated.

True or False

(3) If a pump moves 3 positive ions out and 2 positiveions in against their concentration gradients, the membranepotential in the cell will become more positive.

True or False

skyrabbit531

Calculate the maximum [glucose]in/[glucose]out ratio that can beachieved by the plasma membrane Na+-Glucose symporter of anepithelial cell when the concentration of Na+ inside the cell is 2mM, the concentration of Na+ outside the cell is 15 mM, themembrane potential is -70 mV (inside is more negative) andtemperature is 298K. Assume that the Na+ ions are moving fromoutside to the inside of the cell.

mauvecheetah390

**Please only answer if you are 100% correct!

1. Why are Na+, K+, and Clâ the only ions considered in the GK equation when calculating resting membrane potential (Vm)?

A. These ions are found in the highest concentrations inside the cell

B. These are the ions to which cell membranes are permeable at rest

C. Only these ions have enough charge to influence Vm

D. These ions bind to receptors that increase the charge on the membrane

2. Voltage-regulated channels are located

A. on the neuron cell body only

B. within the cytosol only

C. in the membranes of axons only

D. in the membranes of dendrites only

E. in the membranes of dendrites, in the membranes of axons, and on the neuron cell body

3. As the charge on the membrane of a typical neuron approaches 0 from -70 mV, the cell is

A. hyperpolarizing and becoming more difficult to stimulate

B. only becoming more difficult to stimulate

C. only hyperpolarizing

D. only depolarizing

E. only repolarizing

BIOLOGY 3P03 Lecture Notes - Lecture 6: Colander, Resting Potential, Current Source

Document Summary

Get access

Related Documents

BIOLOGY 3P03 Lecture Notes - Lecture 2: Electrical Network, Lipid Bilayer, Net Force

BIOLOGY 3P03 Lecture 3: Membrane Potential Ionic Steady State

BIOLOGY 3P03 Lecture Notes - Lecture 3: Ouabain, Atp Hydrolysis, Dinitrophenol

Related Questions