Cardio Tutorial 2

Cardio Tutorial 2 - Contact Info Ryan Luther...

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

View Full Document Right Arrow Icon
Contact Info Ryan Luther –  ryan.luther@mail.mcgill.ca Jessie Chai –  zhijin.chai@mail.mcgill.ca Feras Al Halabi –  feras.al-halabi@mail.mcgill.ca Please try to present all you questions and doubts  by 10 pm on Tuesday the 11 th  of March to give  us enough time to reply to them.
Background image of page 1

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

View Full DocumentRight Arrow Icon
Activation Sequence and ECG
Background image of page 2
Activation Sequence of the Heart 1 - SA node 2 - Right atrium 3- AV node  4- Left atrium 5 - Bundle of His  6 - Left and right bundle branches  (interventricular septum) 7 - Purkinje Fibers
Background image of page 3

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

View Full DocumentRight Arrow Icon
Local Circuit Currents Potassium travels inside cells through gap  junctions from a region of positive charge to a  region of negative charge Sodium is in the extracellular space and will travel  from a region of positive charge to a region  negative charge
Background image of page 4
Action Potentials  - Ventricular Resting potential ~ -90mV Depolarization Transient Na influx The Na Channels inactivate but there is no  repolarization immediately following this event Plateau K permeability remains low Ca permeability remains high via L-type channels  Sense depolarization and open slowly Remain open longer than Na channels Repolarization Ca and K permeability return to resting state Atrial muscle has the same type of AP The AP lasts much longer than a typical skeletal  muscle AP
Background image of page 5

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

View Full DocumentRight Arrow Icon
Action Potential  - Nodal No steady resting membrane potential Pacemaker potential Gradual decrease in K permeability Upstroke L-type Ca channels T-type Ca channels give the membrane a  final push towards threshold There’s no sodium ions passing through the  membrane WRONG! There is no sodium current I f  is known as the pacemaker current Conducts Na and K Activated by hyperpolarization Also contributes to the pacemaker current How does I f  contribute to the pacemaker  current? pacemaker current: I f (Na + and K + )
Background image of page 6
Quick note on RVT Reentrant ventricular  tachycardia Circus movement of  action potentials  around a scar or  some other type of  damage to ventricular  muscle Wave breakup leads  to fibrillation 
Background image of page 7

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

View Full DocumentRight Arrow Icon
Excitation-Contraction  Coupling (electrical to mechanical) Action potential invasion of the T-tubule Opening of L-type Ca channels in the T- tubule Ca flows into the cytoplasm CA binds to  ryanodine  receptors on the  surface of the SR Opening of the Ca channels intrinsic to  these receptors Flow of Ca into cytosol from SR Increased cytosolic Ca concentration Contraction Mechanical activity will always lag  behind electrical activity
Background image of page 8
Cardiac Cycle Systole:  Isovolumetric contraction : all  valves closed, no volume change 
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 / 48

Cardio Tutorial 2 - Contact Info Ryan Luther...

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