Lecture 4 Action Potential _ Ion Channels web

Lecture 4 Action Potential _ Ion Channels web - The Action...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Click to edit Master subtitle style The Action Potential & Ion Channels Chapter 4
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Announcements FIRST QUIZ: posted on Sakai: 10 questions Submit on-line: DEADLINE 10 PM Friday, Sept. 17 STUDY GROUP: Professor Charles Page Wednesday mornings: 10:15 – 11:15 Room 336 MSLC, ARC Bldg Busch Campus First meeting: September 15th
Background image of page 2
Action Potential (AP) Rapid change in Vm Changes from inside negative to Characteristics 1. ____________triggered by ‘depolarization’ to ~ -40 mV 2. _______________irrespective of strength, if stimulus is above threshold, amplitude & form of AP are constant 3. _________ period: ‘absolute’ & ‘relative’ 1 msec
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Voltage clamp technique Vm is held constant (‘clamped’) at a set value (‘command voltage’) by current passing electrode. Current injected by amplifier is equal (and opposite) to current across membrane caused by evoked change in conductance.
Background image of page 4
Voltage clamp recording Depolarization results in a transient _______current, and a ________, maintained outward current
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Removing Na+ from ECF affects _____ current, but not ________ current 1 2 3 4
Background image of page 6
TTX blocks the sodium current TEA blocks the potassium current Tetrodotoxin, TTX, (found in puffer fish), selectively blocks Na+ channels Tetraethylammonium, TEA, blocks K+ channels Hodgkin & Huxley calculated voltage- and time- dependent changes in gna and gk by rearranging equation for current: gion = Iion/(Vm – Eion)
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Calculation of ____ & ___ from voltage clamp data:
Background image of page 8
Voltage clamp data mostly supported earlier _______ dependency of gna membrane depolarization above threshold → increase in g na increased Na influx → ‘depolarization’ → further increase in g
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 21

Lecture 4 Action Potential _ Ion Channels web - The Action...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online