Summary
Summary Cardiovascular System Physiology
- Course
- Institution
A summarised version of Guyton's physiology for Medical, Dental and Nursing Students. Hope you all find it useful.
[Show more]
3 reviews
By: waseeemrajoub • 5 year ago
By: gharam199717 • 6 year ago
By: mahsarohani39 • 7 year ago
Seller
Follow
lilmiszangel
Reviews received
Content preview
19. Physiology of cardiac muscle. Action potentials in cardiac muscle.Contraction of cardiac muscle. Specialized excitatory and conductive system of
the heart. Ionic basis of automaticity.
Physiology of cardiac muscle
● The heart is composed of:
○ atrial muscle
○ ventricular muscle
■ The atrial and ventricular muscles contract in much the same way
as skeletal muscle
■ The duration of contraction is much longer
● Specialized excitatory and conductive fiber
○ generate rhythmical electrical impulses to cause rhythmical contraction of
the heart muscle
○ conduct these impulses rapidly through the heart
● Cardiac muscle works as a functional syncytium which means that gap junctions
allow action potentials to move from one cell to the next.
● The heart is composed of 2 separate functional syncytiums, the atrial and the
ventricular syncytium.
○ They are separated by fibrous tissue surrounding the valvular rings
○ Action potentials can be conducted from the atrial into the ventricular
syncytium by the A-V bundle - part of the specialized conduction system.
● All or nothing principle
○ If the strength of the stimulus is below the threshold , it will be ineffective.
○ If the stimulus strength reaches the threshold, heart will respond with a
maximum excitation and contraction for the moment.
Action Potentials in the Cardiac Muscle
● The resting membrane potential of cardiac muscle is about 85 to 95 millivolts,
and the action potential is 105 millivolts.
● In cardiac muscle, the fast sodium channels are open at the initiation of the
action potential, but cardiac muscle has unique slow calcium channels, or
calcium-sodium channels. Calcium and sodium ions flow through the slow
channels into the cell after the initial spike of the action potential, and they
maintain the plateau. Calcium that enters the cell through these channels also
promotes cardiac muscle contraction.
● The decrease in cardiac potassium permeability also prevents return of the
membrane potential in cardiac muscle. When the slow calcium-sodium channels
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller lilmiszangel. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.51. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
52355 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now