{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture 3 - NPB113 Electrophysiology 3-1 Activation of the...

Info icon This preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 January 7, 2010 NPB113 Electrophysiology 3-1 Activation of the Heart Topics Parameters that affect conduction through cardiac tissue Spread of Activation through the heart Refractory Properties of Cardiac Tissue and Conduction Tissue Effective Refractory Period (ERP) & Distinction from a Cell’s Absolute Refractory Period Relative Refractory Period (RRP) of a Cardiac Cell and Tissue Channel State of the Inward Current Channels and a Cells ARP and RRP . Affect of ARP and RRP of Cells on ERP and RRP of a Tissue Intracellular Chemical Environments and Cell to Cell Conductivity
Image of page 1

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

View Full Document Right Arrow Icon
2 January 7, 2010 NPB113 Electrophysiology 3-2 Parameters that Govern Cell to Cell Spread of Activation 1. Rate of Rise and Amplitude of AP Faster Rate of Rise and Higher the Amp litude faster electrical coupling between cells and more rapid depolarization of unactivated cell to threshold and AP generation. 2. Number and Conductivity of low resistance junctions ( tight junctions within the Intercalated Disks ) between adjacent cell # and conductivity of the low resistance junction determines electrical coupling among adjacent cells & rate of spread of activation. 3. Geometric Relationship among Adjacent Cells – surface area for contact and cell to cell spread of activation. II orientation , where cells oriented side to side, facilitates cell to cell spread of activation orientation , where the end of one cell abuts the lateral surface of another cell, less effective electrical coupling between cells. 4. Refractory State of Inward Current Channels and Cardiac Tissue the fewer the number of inward current channels in their rested state , the slower the inward current flow reduced rate of rise and amplitude AP slower cell to cell spread of activation
Image of page 2
3 January 7, 2010 NPB113 Electrophysiology 3-3 Structure of SA Node and Sino-Atrial Conduction SA Node – 20mm x 5mm x 1mm (humans) Pacemaker cells center of node Surrounded by Transitional Cells (electrophysiological characteristics both pacemaker cells and atrial muscle cells) Atrial muscle cells surround node. Few low resistant junctions among cells within node. Sino – Atrial Conduction Time slow , 80 – 100 msec. (0.05 M/sec) Most conduction delay between T & At cells. Weak Electrical Coupling + apposition of cell membranes.
Image of page 3

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

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern